HK1163612B - Driving system of electric vehicle - Google Patents

Abstract

A drive system for an electric vehicle,Including: drive motor,Transmission,And the hydraulic system,The gearbox has an input shaftIntermediate shaftOutput shaftThe first transmission unitThe first clutchThe second transmission unit and the second clutch,The drive motor is connected to the input shaft,The input shaft is connected to the intermediate shaft to transmit the power of the drive motor to the intermediate shaft,The first transmission unit is connected between the intermediate shaft and the output shaft,The second transmission unit is connected between the intermediate shaft and the output shaft,The first clutch is used to engage or disengage the power transmission between the intermediate shaft and the first transmission unit,The second clutch is used to engage or disengage the power transmission between the intermediate shaft and the second transmission unit,The first gear ratio of the first transmission unit is greater than the second gear ratio of the second transmission unit.The driving system of the electric vehicle of the present invention can reasonably match the torque and speed characteristics of the driving motor, effectively improving the efficiency of the driving motor under various driving conditions.

Description

Drive system for electric vehicle

Technical Field

The invention relates to the technical field of automobiles, in particular to a driving system of an electric vehicle.

Background

With the rising price of fuel and the environmental pollution caused by the conventional fuel vehicles, the electric vehicles are more and more emphasized. The electric vehicle takes the power battery as a power source and is driven by the driving motor, so that the limitation caused by an engine is eliminated, and the pollution to the environment is reduced.

Conventionally, an electric vehicle is driven by a drive motor and a fixed-ratio reduction gear. It is known that the torque output of the drive motor is large at low rotational speeds, but the efficiency is low. As the rotational speed of the drive motor increases, the efficiency gradually increases, but the torque output is small. For a reducer with a fixed ratio of an electric vehicle and designed by a large torque, the efficiency is slowly improved along with the increase of the rotating speed of a driving motor, and the energy consumption of the vehicle is large when the vehicle runs at a high speed; the speed reducer designed towards high rotating speed has the advantages that although the efficiency is improved quickly along with the increase of the rotating speed, the transmission of the speed reducer is small, the torque transmitted to wheels is small, and the requirements of starting and climbing of the vehicle cannot be met, so that the acceleration performance of the vehicle is poor, and the energy consumption is high when the rotating speed of the vehicle is low. For example, for urban electric buses, parking and starting are accelerated very frequently, resulting in inefficient drive motors. Therefore, the driving device of the traditional electric vehicle cannot simultaneously meet two working conditions of low speed and high speed, the efficiency of the driving motor is low, and the driving range of the electric vehicle is directly shortened under the condition that the energy storage of the battery is unchanged, so that the traditional electric vehicle cannot be suitable for complex road conditions.

Disclosure of Invention

The present invention is directed to solving at least one of the above problems. Therefore, an object of the present invention is to provide a driving system for an electric vehicle, which can reasonably match the torque and rotation speed characteristics of a driving motor, and effectively improve the efficiency of the driving motor under various driving conditions.

A drive system of an electric vehicle according to an embodiment of the present invention includes: a drive motor; a transmission having an input shaft, an intermediate shaft, an output shaft, a first speed change unit, a first clutch, a second speed change unit, and a second clutch, wherein the driving motor is connected to the input shaft, the input shaft is connected to the intermediate shaft so as to transmit power of the driving motor to the intermediate shaft, the first speed change unit is connected between the intermediate shaft and the output shaft so as to transmit power between the intermediate shaft and the output shaft, the second speed change unit is connected between the intermediate shaft and the output shaft so as to transmit power between the intermediate shaft and the output shaft, the first clutch is provided on the intermediate shaft and connected to the first speed change unit so as to couple or decouple power transmission between the intermediate shaft and the first speed change unit, the second clutch is provided on the intermediate shaft and connected to the second speed change unit so as to couple or decouple the intermediate shaft and the second speed change unit Power transmission between the elements, the first transmission unit having a first gear ratio, the second transmission unit having a second gear ratio, the first gear ratio being greater than the second gear ratio; and the hydraulic system is connected with the first clutch to drive the first clutch to be combined or separated, and the hydraulic system is connected with the second clutch to drive the second clutch to be combined or separated.

According to the driving system of the electric vehicle, the transmission is provided with the first speed changing unit and the second speed changing unit, the transmission ratio of the first speed changing unit is larger than that of the second speed changing unit, so that the driving motor can transmit power to wheels through the first speed changing unit and the second speed changing unit selectively, for example, the first speed changing unit is selected at low speed to output large torque, the second speed changing unit is selected at high speed, the speed changing units with different transmission ratios are selected according to different working conditions, the torque and rotating speed characteristics of the driving motor are matched reasonably, the efficiency of the driving motor is improved, the use efficiency of a power battery is improved, and the complicated working conditions of the electric vehicle are met.

In addition, the driving system of the electric vehicle according to the above embodiment of the present invention may further have the following additional technical features:

in one embodiment of the present invention, a first gear is provided on the input shaft, a second gear engaged with the first gear is provided on the intermediate shaft, and the input shaft and the intermediate shaft are connected through the first and second gears.

In one embodiment of the present invention, the first speed change unit includes a third gear provided on the counter shaft and a fourth gear provided on the output shaft and meshed with the third gear.

In one embodiment of the present invention, the third gear is rotatably fitted over the intermediate shaft, the fourth gear is fixed to the output shaft, the driving portion of the first clutch is fixed to the intermediate shaft, and the driven portion of the first clutch is connected to the third gear.

In one embodiment of the present invention, the second speed change unit includes a fifth gear provided on the counter shaft and a sixth gear provided on the output shaft and meshed with the fifth gear.

In one embodiment of the present invention, the fifth gear is rotatably fitted over the intermediate shaft, the sixth gear is fixed to the output shaft, the driving part of the second clutch is fixed to the intermediate shaft, and the driven part of the second clutch is connected to the fifth gear.

In one embodiment of the present invention, the transmission further includes a third speed change unit connected between the intermediate shaft and the output shaft to transmit power between the intermediate shaft and the output shaft, and a third clutch provided on the intermediate shaft and connected to the third speed change unit to engage or cut off power transmission between the intermediate shaft and the third speed change unit, wherein the hydraulic system is connected to the third clutch to drive the third clutch to engage or disengage, the third speed change unit has a third gear ratio, and the second gear ratio is larger than the third gear ratio.

In one embodiment of the present invention, the third speed change unit includes a seventh gear provided on the counter shaft and an eighth gear provided on the output shaft and meshed with the seventh gear.

In one embodiment of the present invention, the seventh gear is rotatably fitted over the intermediate shaft, the eighth gear is fixed to the output shaft, the driving part of the third clutch is fixed to the intermediate shaft, and the driven part of the third clutch is connected to the seventh gear.

In one embodiment of the invention, the second clutch and the third clutch share one active part.

In one embodiment of the present invention, the first to third clutches are all wet clutches.

In one embodiment of the present invention, the axis of the input shaft and the axis of the output shaft are on the same straight line, and the axis of the intermediate shaft is parallel to the axes of the input shaft and the output shaft.

In one embodiment of the present invention, the hydraulic system comprises: an oil tank; the first clutch driving circuit comprises a first driving hydraulic cylinder and a first proportional valve, the first proportional valve is respectively connected with the first driving hydraulic cylinder and the oil tank, a piston of the first driving hydraulic cylinder is connected with a driving part of the first clutch, the second clutch driving circuit comprises a second driving hydraulic cylinder and a second proportional valve, the second proportional valve is respectively connected with the second driving hydraulic cylinder and the oil tank, and a piston of the second driving hydraulic cylinder is connected with the driving part of the second clutch; the built-in pump is driven by the intermediate shaft, an inlet of the built-in pump is connected with the oil tank, and an outlet of the built-in pump is respectively connected with the first proportional valve and the second proportional valve; a first check valve connected in series on an outlet side of the built-in pump; the external pump is driven by an external pump motor, an inlet of the external pump is connected with the oil tank, and an outlet of the external pump is respectively connected with the first proportional valve and the second proportional valve; and the second one-way valve is connected in series at the outlet side of the external pump, wherein the first one-way valve and the internal pump which are connected in series are connected in parallel between the oil tank and the first and second proportional valves with the second one-way valve and the external pump which are connected in series.

In one embodiment of the invention, the hydraulic system further comprises a third one-way valve in parallel with the built-in pump.

In one embodiment of the invention, the hydraulic system further comprises first and second filters, the first filter being connected between the inlets of the on-board and off-board pumps and the tank, the second filter being connected between the first and second one-way valves and the first and second proportional valves.

In one embodiment of the invention, the hydraulic system further comprises a relief valve connected in parallel with the first check valve and the built-in pump connected in series and the external pump and the second check valve connected in series.

In one embodiment of the invention, the hydraulic system further comprises an accumulator connected between the first and second one-way valves and the first and second proportional valves.

In one embodiment of the invention, the first clutch drive circuit further comprises a first damper connected between the first proportional valve and the first drive cylinder, and the second clutch drive circuit further comprises a second damper connected between the second proportional valve and the second drive cylinder.

In one embodiment of the invention, the hydraulic system further comprises a pressure regulating valve connected in parallel with the built-in pump for providing the drive system with lubricating oil, and a fourth one-way valve connected between the pressure regulating valve and an outlet of the built-in pump.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic diagram of a drive system of an electric vehicle according to an embodiment of the invention;

FIG. 2 is a schematic structural diagram of a transmission of the drive system of FIG. 1; and

fig. 3 is a schematic diagram of a hydraulic system of a drive system of an electric vehicle according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

A drive system of an electric vehicle according to an embodiment of the invention is described below with reference to the drawings.

The drive system of the electric vehicle according to the embodiment of the present invention as shown in fig. 1 to 3 includes a drive motor 1, a transmission, and a hydraulic system.

Specifically, the transmission has an input shaft 2, an intermediate shaft 13, an output shaft 5, a first shift unit B1, a first clutch 15, a second shift unit B2, and a second clutch 11. The driving motor 1 is connected with the input shaft 2 to drive the input shaft 2 to rotate. In a specific example, the driving motor 1 is connected to the input shaft 2 by splines as shown in fig. 2, but the present invention is not limited thereto, and the driving motor 1 may be directly connected to the input shaft 2 by other means. The driving motor 1 is directly connected to the input shaft 2, and unlike a conventional vehicle using an engine, a clutch and a torque converter may not be provided between the driving motor and the input shaft 2, thereby improving power transmission efficiency and simplifying the structure.

The input shaft 2 is connected to an intermediate shaft 13 so as to transmit the power of the drive motor 1 to the intermediate shaft 13. For example, in one particular example, the input shaft 2 is connected to the intermediate shaft 13 through a gear pair comprising a first gear 3 and a second gear 8, the first gear 3 being mounted on the input shaft 2, the second gear 8 being mounted on the intermediate shaft 13, the first gear 3 and the second gear 8 being in mesh with each other.

The first shift unit B1 is connected between the intermediate shaft 13 and the output shaft 5 to transmit power between the intermediate shaft 13 and the output shaft 5. The second shift unit B2 is connected between the intermediate shaft 13 and the output shaft 5 to transmit power between the intermediate shaft 13 and the output shaft 5.

The first clutch 15 is provided on the intermediate shaft 13 and connected to the first speed change unit B1 to engage or cut off power transmission between the intermediate shaft 13 and the first speed change unit B1, in other words, the first clutch 15 is used to engage or cut off power transmission between the intermediate shaft 13 and the output shaft 5.

The second clutch 11 is provided on the intermediate shaft 13 and connected to the second shift unit B2 to engage or cut off power transmission between the intermediate shaft 13 and the second shift unit B2, in other words, the second clutch 11 is used to engage or cut off power transmission between the intermediate shaft 13 and the output shaft 5. The first shift unit B1 has a first gear ratio and the second shift unit B2 has a second gear ratio, the first gear ratio being greater than the second gear ratio.

The hydraulic system is connected with the first clutch 15 to drive the first clutch 15 to be combined or separated, and the hydraulic system is also connected with the second clutch 11 to drive the second clutch 11 to be combined or separated.

According to the driving system of the electric vehicle, the transmission is provided with the first speed changing unit and the second speed changing unit, the transmission ratio of the first speed changing unit is larger than that of the second speed changing unit, so that the torque and rotating speed characteristics of the driving motor can be reasonably matched, the working efficiency of the driving motor under various working conditions during vehicle running is effectively improved, more energy is saved, the driving range of the vehicle is improved, and the structure of the driving system is simple. More specifically, when the electric vehicle is running at a low speed, such as at a start, a hill climb or an acceleration, and the required output torque is large, the hydraulic system may incorporate the first clutch 15, in other words, the vehicle is switched to the first forward gear, the power of the driving motor 1 is transmitted to the input shaft 2, the input shaft 2 is transmitted to the intermediate shaft 13 through the first gear 3 and the second gear 8, the intermediate shaft 13 is transmitted to the output shaft 5 through the first clutch 15 and the first speed change unit B1, and then transmitted to the wheels WH, and since the first speed change unit B1 has a large gear ratio, the torque transmitted to the wheels WH is large, and the large torque required for the low-speed running of the vehicle is satisfied. When the vehicle speed increases and the required torque is small, the hydraulic system disconnects the first clutch 15 and the vehicle is switched to the second forward gear by engaging the second clutch 11, that is, the vehicle is switched to the second forward gear, so that the power is transmitted from the intermediate shaft 13 to the output shaft 5 through the second clutch 11 and the second transmission unit B2, and since the second transmission unit B2 has a smaller gear ratio, the torque transmitted to the wheels is reduced, the rotating speed of the wheels WH is increased, and the requirement of low torque and high rotating speed is met.

When the vehicle needs to reverse, the drive motor 1 is reversed, the hydraulic system disconnects the second clutch 11, engages the first clutch 15, in other words, the vehicle is shifted to a reverse gear position, and power is transmitted to the wheels WH through the first clutch 15 and the first transmission unit B1, and since a large output torque is required for reverse, the engagement of the first clutch 15 is selected to transmit power through the first transmission unit B1 having a large gear ratio.

In summary, by selecting a proper speed change unit, the torque and rotation speed characteristics of the driving motor 1 are reasonably matched, and the working efficiency of the driving motor 1 in running under various working conditions of the vehicle is optimized, so that the effects of saving energy, reducing consumption and increasing the driving range of the electric vehicle are achieved, and the electric vehicle has the characteristics similar to those of the conventional vehicle using an engine.

The drive system of the electric vehicle according to the embodiment of the invention described above has the first shift unit B1 and the second shift unit B2, i.e., the vehicle has two forward gear positions and one reverse gear position. It is to be understood that the present invention is not limited thereto, and the electric vehicle driving system according to the embodiment of the present invention may have a suitable number of speed change units, for example, three or four speed change units.

In one particular embodiment of the present invention, as shown in fig. 1-3, the transmission further includes a third shift unit B3 and a third clutch 10. The third speed change unit B3 is connected between the intermediate shaft 13 and the output shaft 5 to transmit power between the intermediate shaft 13 and the output shaft 5, and the third clutch 10 is provided on the intermediate shaft 13 and connected to the third speed change unit B3 to engage or cut off power transmission between the intermediate shaft 13 and the third speed change unit B3, in other words, the third clutch 10 is used to engage or cut off power transmission between the intermediate shaft 13 and the output shaft 5. The hydraulic system is connected to the third clutch 10 to drive the third clutch 10 to be engaged or disengaged, and the third shift unit B3 has a third gear ratio, wherein the second gear ratio is greater than the third gear ratio.

For example, when the speed of the vehicle is further increased, the hydraulic system disconnects the first clutch 15 and the second clutch 11, in conjunction with the third clutch 10, i.e., the vehicle is shifted to the third forward gear, so that power is transmitted from the intermediate shaft 13 to the output shaft 5 through the third transmission unit B3, and since the third transmission unit B3 has a smaller gear ratio than the second transmission unit B2 and the first transmission unit B1, the output torque is smaller, but the rotation speed is higher, so that when the speed of the vehicle is further increased, the power is transmitted through the third clutch 10 and the third transmission unit B3, the efficiency of the driving motor 1 can be further increased, and the energy consumption can be reduced.

Advantageously, the first clutch 15, the second clutch 11 and the third clutch 10 may all be wet clutches. In a preferred embodiment of the present invention, as shown in fig. 1 and 2, the axis of the input shaft 2 is on the same axis as the axis of the output shaft 5, and the axis of the intermediate shaft 13 is parallel to the axes of the input shaft 2 and the output shaft 5, so that the size of the transmission can be reduced, the transmission is compact, and the installation space is saved.

As shown in fig. 1 and 2, it is preferable that the second clutch 11 and the third clutch 10 share one active portion, and therefore, it is possible to further reduce the size of the transmission, simplify the structure of the transmission, and reduce the manufacturing cost. In the embodiment shown in fig. 1 and 2, the first clutch 15 and the first transmission unit B1 are closest to the wheels WH, the third clutch 10 and the third transmission unit B3 are farthest from the wheels WH, and the second clutch 11 and the second transmission unit B2 are located between the first clutch 15 and the third clutch 10. It is to be understood, however, that the above-described arrangements are preferred embodiments and that one skilled in the art may arrange them according to a particular application.

As shown in fig. 1 and 2, in some embodiments of the present invention, the first speed changing unit B1 includes a third gear 14 provided on the intermediate shaft 13 and a fourth gear 7 provided on the output shaft 5 and engaged with the third gear 14, and the third gear 14 and the fourth gear 7 may be cylindrical gears, whereby the first speed changing unit B1 is simple in structure. The third gear 14 is rotatably sleeved on the output shaft 5, the fourth gear 7 is fixed on the output shaft 5, the driving part of the first clutch 15 is fixed on the intermediate shaft 13, and the driven part of the first clutch 15 is connected with the third gear 14.

The second shift unit B2 includes a fifth gear 12 provided on the counter shaft 13 and a sixth gear 6 provided on the output shaft 5 and meshing with the fifth gear 12. The fifth gear 12 is rotatably sleeved on the intermediate shaft 13, the sixth gear 6 is fixed on the output shaft 5, the driving part of the second clutch 11 is fixed on the intermediate shaft 13, and the driven part of the second clutch 11 is connected with the fifth gear 12.

The third shift unit B3 includes a seventh gear 9 provided on the counter shaft 13 and an eighth gear 4 provided on the output shaft 5 and meshed with the seventh gear 9. The seventh gear 9 is rotatably sleeved on the intermediate shaft 13, the eighth gear 4 is fixed on the output shaft 5, the driving part of the third clutch 10 is fixed on the intermediate shaft 13, and the driven part of the third clutch 10 is connected with the seventh gear 9.

A hydraulic system of a drive system of an electric vehicle according to an embodiment of the present invention will be described with reference to fig. 3.

As shown in fig. 3, the hydraulic system includes a tank 16, a first clutch drive circuit L1 for driving the first clutch 15, a second clutch drive circuit L2 for driving the second clutch 11, a third clutch drive circuit L3 for driving the third clutch 10, an internal pump 18, a first check valve 23 connected in series to an outlet side of the internal pump 18, an external pump 20, and a second check valve 22 connected in series to an outlet side of the external pump 20.

It is understood that when the transmission has only the first and second shift units B1 and B2, the third clutch drive circuit L3 need not be provided, and when the transmission has more shift units, the clutch drive circuits may be increased accordingly.

As shown in fig. 3, the first, second, and third clutch drive circuits L1, L2, and L3 are connected in parallel with each other.

The first clutch drive circuit L1 includes a first drive hydraulic cylinder 151 and a first proportional valve 32, for example, the first proportional valve 32 may be a two-position, three-way solenoid valve. In the preferred embodiment, the first clutch drive circuit L1 also includes a first damper 38 connected between the first proportional valve 32 and the first drive cylinder 151. Alternatively, a first oil pressure sensor 35 for measuring the oil pressure of the first clutch drive circuit L1 may be provided between the first damper 38 and the first proportional valve 32.

Similarly, the second clutch drive circuit L2 includes the second drive hydraulic cylinder 111 and the second proportional valve 31. A second shock absorber 37 is connected between the second proportional valve 31 and the second drive hydraulic cylinder 111. A second oil pressure sensor 34 for measuring the oil pressure of the second clutch drive circuit L2 may be provided between the second damper 37 and the second proportional valve 31.

The third clutch drive circuit L3 includes a third drive hydraulic cylinder 101 and a third proportional valve 30. A third damper 36 is also connected between the third proportional valve 30 and the third drive cylinder 101. A third oil pressure sensor 33 for measuring the oil pressure of the third clutch drive circuit L3 may be provided between the third damper 36 and the third proportional valve 30.

As shown in fig. 3, the first proportional valve 32 is connected to the first driving hydraulic cylinder 151 and the tank 16, respectively, the second proportional valve 31 is connected to the second driving hydraulic cylinder 111 and the tank 16, respectively, the third proportional valve 30 is connected to the third driving hydraulic cylinder 101 and the tank 16, respectively, and the piston of the first driving hydraulic cylinder 151 is connected to the driving part of the first clutch 15 to drive the first clutch 15 to be engaged or disengaged. The piston of the second driving hydraulic cylinder 111 is connected to the active part of the second clutch 11 to drive the second clutch 11 to engage or disengage. The piston of the third driving hydraulic cylinder 101 is connected to the driving part of the third clutch 10 to drive the third clutch 10 to be engaged or disengaged.

The internal pump 18 is driven by the intermediate shaft 13, and the external pump 20 is driven by the external pump motor M. The inlets of the internal pump 18 and the external pump 20 are connected to the tank 16, and preferably a first filter 17 is provided between the inlets of the internal pump 18 and the external pump 20 and the tank 16. The outlets of the internal pump 18 and the external pump 20 are respectively connected with the first proportional valve 32, the second proportional valve 31 and the third proportional valve 30, preferably, a second filter 27 is arranged between the outlets of the internal pump 18 and the external pump 20 and the first proportional valve 32, the second proportional valve 31 and the third proportional valve 30, and the filtering precision of the second filter 27 is higher than that of the first filter 17, so that the cleanliness of the hydraulic oil entering the first to third proportional valves 32, 31 and 30 is further improved.

The internal pump 18 is connected with the external pump 20 in parallel, the first check valve 23 is connected with the outlet side of the internal pump 18 in series, the second check valve 22 is connected with the outlet side of the external pump 20 in series, and the first check valve 23 and the internal pump 18 which are connected with each other in series and the second check valve 22 and the external pump 20 which are connected with each other in series are connected between the oil tank 16 and the first to third proportional valves 32, 31 and 30 in parallel.

In some embodiments of the invention, the hydraulic system further comprises an accumulator 29 connected between the first and second check valves 23, 22 and the first to third proportional valves 32, 31, 30, and a main oil pressure sensor 28 for measuring the oil pressure in the main oil line L of the hydraulic system.

Preferably, the hydraulic system further includes a relief valve 21, and the relief valve 21 is connected in parallel with the first check valve 23 and the internal pump 18 in series and the external pump 20 and the second check valve 22 in series to relief the hydraulic oil in the main oil path L to the oil tank 16. In some embodiments of the present invention, the hydraulic system further comprises a pressure regulating valve 26, the pressure regulating valve 26 being connected in parallel with the internal pump 18 for supplying lubricating oil to the various gear pairs, bearings of the drive system, e.g. the transmission. A fourth check valve 24 is provided between the pressure regulating valve 26 and the outlet of the internal pump 18 for generating a back suction of the pressure regulating valve 26 when the internal pump 18 is reversed. The pressure regulating valve 26 is connected in series with two damping members 25A and 25B, and when the vehicle is started, the amount of oil supplied by the built-in pump 18 is gradually increased, and the pressure in the main oil passage is rapidly increased by the action of the damping members 25A and 25B and after supplementing a slight leakage that may exist in the pressure regulating valve 26. .

In a preferred embodiment of the present invention, the internal pump 18 is also connected in parallel with a third check valve 19 for preventing the internal pump 18 from sucking empty when sucking back (e.g., reversing).

The operation of the hydraulic system of the drive system according to the embodiment of the present invention is briefly described below.

As shown in fig. 2, after the hydraulic system is started, the internal pump 18 and/or the external pump 20 sucks oil from the oil tank 16 through the filter 17, and the hydraulic oil enters the main oil passage L and then enters one of the first clutch drive circuit L1, the second clutch drive circuit L2, and the third clutch drive circuit L3, that is, one of the first drive hydraulic cylinder 151, the second drive hydraulic cylinder 111, and the third drive hydraulic cylinder 101.

For convenience of description, the driving of the first driving hydraulic cylinder 151 is described as an example, and it is understood that these operations are also applicable to the second clutch driving circuit L2 and the third clutch driving circuit L3. The piston of the first driving hydraulic cylinder 151 is pressed into the retraction spring under the action of oil pressure to push the driving part and the driven part of the first clutch 15 to be combined, so that power is transmitted to the output shaft 5 from the intermediate shaft 13 through the first clutch 15 (namely, through the third gear 14 and the fourth gear 7) and then transmitted to the wheels WH. When the first clutch 15 is disengaged, hydraulic oil is communicated with the oil tank 16, the oil pressure in the first driving hydraulic cylinder 151 is rapidly reduced, the piston of the first driving hydraulic cylinder 151 is rapidly moved under the pushing of the return spring, the hydraulic oil flows back to the oil tank 16, the driving part and the driven part of the first clutch 15 are separated, and the power transmission between the intermediate shaft 13 and the output shaft 5 is cut off.

According to the drive system of the embodiment of the invention, the built-in pump 18 is normally used for supplying oil, the built-in pump 18 is driven by the intermediate shaft 13 to rotate, and the first check valve 23 only allows hydraulic oil to flow from the built-in pump 18 to the first to third clutch drive circuits L1, L2 and L3, so that the pressure impact of the system is prevented from influencing the operation of the built-in pump 18, and the hydraulic oil of the system is prevented from flowing backwards.

According to the embodiment of the present invention, the third check valve 19 only allows the hydraulic oil to flow from the oil tank 16 to the outlet side of the internal pump 18, so that the internal pump 18 can be prevented from being sucked empty when sucking back, for example, when the internal pump 18 rotates reversely in reverse, the outlet of the internal pump 10 can suck oil from the oil tank 16 through the third check valve 19, and the internal pump 18 is prevented from being damaged, that is, oil circulation is formed among the oil tank 16, the first filter 17, the third check valve 19 and the internal pump 18, so that the internal pump 18 is prevented from being sucked empty.

The fourth check valve 24 allows only the hydraulic oil to flow from the internal pump 18 toward the pressure-regulating valve 26, and can prevent the oil for lubrication from flowing backward.

According to the embodiment of the invention, in the case that the oil pressure of the internal pump 18 is too low, the external pump motor M is started to drive the external pump 20, the external pump 20 can supplement the oil pressure into the main oil path L of the hydraulic system, the second check valve 22 only allows the hydraulic oil to flow from the external pump 20 to the first to third clutch driving circuits L1, L2 and L3, and the pressure impact of the system can be prevented from affecting the operation of the external pump 20, and the hydraulic oil in the system can be prevented from flowing backwards.

The internal pump 18 supplies oil in the event that the hydraulic system requires oil, the remaining amount of oil entering the lubrication or return tank 16. By providing the accumulator 29 for connection, the external pump 20 may be operated intermittently, as described above, with the relief valve 21 acting as a relief.

In the hydraulic system described above, the lubrication system of the vehicle is supplied with lubricating oil through the pressure regulating valve 26.

According to an embodiment of the invention, the hydraulic oil is provided by an external pump 20 driven by an external pump motor M and an internal pump 18 driven by the intermediate shaft 13. By arranging the external pump 20, before the electric vehicle is started, the external pump 20 can supply oil to the first clutch 15, so that the first clutch 15 is connected, zero-rotation-speed starting is realized, an idling working condition is avoided, energy loss of the electric vehicle is reduced, and the utilization efficiency of electric energy is improved.

As mentioned above, the accumulator 29 is used for accumulating energy and the pressure regulating valve 26 may be used for regulating the oil pressure. When the electric vehicle is stationary and the internal pump 18 is not operating with no flow, the pressure regulating valve 26 is closed. When the electric vehicle is started, the oil amount of the internal pump 18 is slowly increased, the hydraulic oil is acted by the 25A and 25B of the regulator valve 26 and the pressure in the main oil passage L rises in a short time after a slight leak of the supplemental regulator valve 26. During the running of the electric vehicle, the amount of oil required for lubrication is gradually supplied after the pressure in the main oil passage L rises. When the pressure in the main oil passage L rises to a certain pressure, the hydraulic oil flows to the inlet of the built-in pump 18, and the work load of the filter 17 is reduced.

During vehicle travel, excess energy is stored in the accumulator 29 and the stored energy can be used to perform shifting operations, improving transmission efficiency.

In the driving system of the electric vehicle according to the embodiment of the invention, the first clutch 15, the second clutch 11 and the third clutch 10 are all controlled by the hydraulic system, and the first clutch 15 can be combined before the vehicle is started, so that the situation that the driving motor 1 idles after the vehicle is started does not exist, and as long as the driving motor 1 starts to run, the power can be transmitted to the transmission, the zero-rotation-speed starting is realized, the electric energy loss of the vehicle is reduced, and the utilization rate of the electric energy is improved. And, when the hydraulic oil that built-in pump 18 provided is not enough, can supplement the hydraulic oil through external pump 20, improved the performance of electric vehicle.

Therefore, the driving system provided by the embodiment of the invention can realize zero-rotating-speed starting, can automatically carry out variable-speed gear shifting according to the degree of pedal depression and the change of vehicle speed, reasonably matches the torque and rotating speed characteristics of the driving motor, effectively improves the working efficiency of the driving motor under various working conditions when the vehicle runs, optimizes the motor efficiency under various working conditions when the vehicle runs, and further achieves the purposes of saving energy, reducing consumption and increasing the driving range of the electric vehicle. For example, the driving system is particularly suitable for urban buses which need frequent acceleration, deceleration, parking and starting.

The operation of the drive system according to the embodiment of the present invention will be described below with reference to fig. 1, and in the following description, the transmission of the drive system including the first to third shifting units B1, B2 and B3 will be exemplified, and it will be understood by those skilled in the art that the transmission of the drive system according to the embodiment of the present invention may include two or more than three shifting units.

First, a parking range of a drive system of an electric vehicle according to an embodiment of the present invention is described with reference to fig. 1. When the electric vehicle is in a stopped state, the driving portion and the driven portion of the first clutch 15 are separated from each other; the driving part and the driven part of the second clutch 11 are separated from each other; the driving part and the driven part of the third clutch 10 are separated from each other, that is, the three clutches are all in a separated state, and the power transmission from the driving motor 1 to the output shaft 5 is cut off.

Next, a first forward gear of a drive system of an electric vehicle according to an embodiment of the invention is described with reference to fig. 1. When the electric vehicle is operating at a start or a low speed, the shift control system disengages the second clutch 11 and the third clutch 10 through the shift mechanism, and combines the driving portion and the driven portion of the first clutch 15. Then, the power transmission route of the first forward gear is: drive motor 1 → input shaft 2 → first gear 3 → second gear 8 → intermediate shaft 13 → first clutch 15 → third gear 14 → fourth gear 7 → output shaft 5. At this time, the rotational speed of the drive motor 1 is low, the output torque is maximum, the gear ratio is maximum, and the power transmitted to the wheels is also maximum. Both shift control systems and shifting mechanisms are known to those skilled in the art and will not be described in detail herein.

Next, a second forward gear of the drive system of the electric vehicle according to the embodiment of the invention is described with reference to fig. 1. When the electric vehicle is running at a medium speed, the shift control system disengages the first clutch 15 and the third clutch 10 through the shift mechanism, and combines the driving part and the driven part of the second clutch 11. For example, when the first forward gear is switched to the second forward gear, the gear shift control system senses the current running state of the electric vehicle through related sensors, and then judges that the vehicle enters the running gear, and the second clutch 11 is engaged while the first clutch 15 is disengaged, so that the purpose of gear shift is achieved. Wherein, the power transmission route of the second forward gear is as follows: the drive motor 1 → the input shaft 2 → the first gear 3 → the second gear 8 → the intermediate shaft 13 → the second clutch 11 → the fifth gear 12 → the sixth gear 6 → the output shaft 5. At this time, the larger the transmission ratio, the lower the efficiency of the drive motor 1, and the smaller the transmission ratio of the second forward gear as compared with the first forward gear, the higher the efficiency of the drive motor 2, and the higher the energy utilization rate.

Next, a third forward gear of the drive system of the electric vehicle according to the embodiment of the invention is described with reference to fig. 1. When the electric vehicle is running at high speed, the shift control system disengages the first clutch 15 and the second clutch 11 through the shift mechanism, and couples the driving portion and the driven portion of the third clutch 10. For example, when the second forward speed is switched to the third forward speed, the third clutch 10 is engaged while the second clutch 11 is disengaged, similar to when the first forward speed is switched to the second forward speed. The power transmission route of the third forward gear is as follows: motor 1 → input shaft 2 → first gear 3 → second gear 8 → intermediate shaft 13 → third clutch 10 → seventh gear 9 → eighth gear 4 → output shaft 5. At this time, since the driving motor has lower efficiency as the gear ratio is larger, the gear ratio of the third forward speed is the smallest, the efficiency of the driving motor is the highest, and the energy utilization rate is the highest, compared to the first forward speed and the second forward speed.

Finally, reverse gear of the drive system of the electric vehicle according to the embodiment of the invention is described with reference to fig. 1. When the vehicle runs in reverse gear, the shift control system disengages the second clutch 11 and the third clutch 10 through the shift mechanism, and combines the driving portion and the driven portion of the first clutch 15. Of course, the drive motor 1 rotates in reverse when the reverse gear is performed. The power transmission route of the reverse gear is as follows: drive motor 1 → input shaft 2 → first gear 3 → second gear 8 → intermediate shaft 13 → first clutch 15 → third gear 14 → fourth gear 7 → output shaft 5.

The driving system of the electric vehicle provided by the embodiment of the invention adopts the transmission comprising at least two speed change units, can meet various complex working conditions of vehicle running, is more energy-saving and has a simple structure.

In the above embodiment, the transmission provides three forward gears and one reverse gear, which satisfies both the requirement of large torque demand when the vehicle is started and climbs a slope and the requirement of maximum vehicle speed when the vehicle runs on a flat road. The torque demand is large when the vehicle starts, climbs and accelerates, and the gear of the speed changer can be switched to a low gear, namely a first forward gear or a second forward gear. Since the transmission ratio in the low gear is relatively large, the torque transmitted to the wheels is also relatively large. When the vehicle is running on a flat road, the vehicle speed is high, and the vehicle can be switched to a high gear, namely a third forward gear. At this time, the transmission ratio of the transmission is small, and the torque transmitted to the wheels is reduced, but the wheel rotation speed is increased, and the maximum vehicle speed can be achieved. Meanwhile, gear switching is reasonably controlled through the gear shifting control system, the torque and rotating speed characteristics of the driving motor are reasonably matched, and the working efficiency of the driving motor under various working conditions when the vehicle runs is optimized, so that the purposes of saving energy, reducing consumption and increasing the driving range of the electric vehicle are achieved.

According to the embodiment of the invention, three forward gears of the transmission are independent, and gear shifting is realized by controlling the separation and combination of the driving part and the driven part of each clutch. Moreover, those skilled in the art can reasonably control the shift control system so that there is almost no power interruption during the shifting process, and therefore no significant deceleration feeling is generated during the shifting process. The transmission of the drive system according to the embodiment of the invention is simple in structure as compared with a conventional automatic transmission.

In addition, the second clutch and the third clutch share one clutch driving part, so that the structure of the transmission is more compact, and the occupied space of the transmission is saved. Moreover, the input shaft and the output shaft are arranged in a collinear way, so that the effect of a transmission with a complex structure and a rotating shaft (such as a planetary gear) is realized by a parallel coaxial structure with a simple structure, and the driving system of the electric vehicle according to the embodiment of the invention has the advantages of more compact structure and lower cost.

According to the driving system provided by the embodiment of the invention, before the electric vehicle starts, the external pump can drive the first clutch to realize the first forward gear, and then the driving motor 1 is controlled to start, so that the vehicle can be started without any change.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims (18)

1. A drive system of an electric vehicle, characterized by comprising:

a drive motor;

a transmission having an input shaft, an intermediate shaft, an output shaft, a first speed change unit, a first clutch, a second speed change unit, and a second clutch, wherein the driving motor is connected to the input shaft, the input shaft is connected to the intermediate shaft so as to transmit power of the driving motor to the intermediate shaft, the first speed change unit is connected between the intermediate shaft and the output shaft so as to transmit power between the intermediate shaft and the output shaft, the second speed change unit is connected between the intermediate shaft and the output shaft so as to transmit power between the intermediate shaft and the output shaft, the first clutch is provided on the intermediate shaft and connected to the first speed change unit so as to couple or decouple power transmission between the intermediate shaft and the first speed change unit, the second clutch is provided on the intermediate shaft and connected to the second speed change unit so as to couple or decouple the intermediate shaft and the second speed change unit Power transmission between the elements, the first transmission unit having a first gear ratio, the second transmission unit having a second gear ratio, the first gear ratio being greater than the second gear ratio; and

a hydraulic system connected to the first clutch to drive the first clutch to engage or disengage and connected to the second clutch to drive the second clutch to engage or disengage, the hydraulic system comprising:

an oil tank;

the first clutch driving circuit comprises a first driving hydraulic cylinder and a first proportional valve, the first proportional valve is respectively connected with the first driving hydraulic cylinder and the oil tank, a piston of the first driving hydraulic cylinder is connected with a driving part of the first clutch, the second clutch driving circuit comprises a second driving hydraulic cylinder and a second proportional valve, the second proportional valve is respectively connected with the second driving hydraulic cylinder and the oil tank, and a piston of the second driving hydraulic cylinder is connected with the driving part of the second clutch;

the built-in pump is driven by the intermediate shaft, an inlet of the built-in pump is connected with the oil tank, and an outlet of the built-in pump is respectively connected with the first proportional valve and the second proportional valve; and

a first check valve connected in series on an outlet side of the built-in pump;

the external pump is driven by an external pump motor, an inlet of the external pump is connected with the oil tank, and an outlet of the external pump is respectively connected with the first proportional valve and the second proportional valve; and

the first check valve and the built-in pump which are connected in series are connected in parallel between the oil tank and the first and second proportional valves with the second check valve and the built-in pump which are connected in series.

2. The drive system of an electric vehicle according to claim 1, wherein a first gear is provided on the input shaft, a second gear that meshes with the first gear is provided on the intermediate shaft, and the input shaft and the intermediate shaft are connected through the first and second gears.

3. The drive system of an electric vehicle according to claim 1, characterized in that the first speed change unit includes a third gear provided on the counter shaft and a fourth gear provided on the output shaft and meshed with the third gear.

4. The electric vehicle drive system of claim 3, wherein the third gear is rotatably journaled on the countershaft, the fourth gear is fixed to the output shaft, the driving portion of the first clutch is fixed to the countershaft, and the driven portion of the first clutch is connected to the third gear.

5. The drive system of an electric vehicle according to claim 1, characterized in that the second transmission unit includes a fifth gear provided on the counter shaft and a sixth gear provided on the output shaft and meshed with the fifth gear.

6. The electric vehicle drive system of claim 5, wherein the fifth gear is rotatably journaled on the countershaft, the sixth gear is fixed to the output shaft, the driving portion of the second clutch is fixed to the countershaft, and the driven portion of the second clutch is connected to the fifth gear.

7. The drive system of an electric vehicle according to claim 1, characterized in that the transmission further includes a third speed change unit connected between the intermediate shaft and the output shaft to transmit power between the intermediate shaft and the output shaft, and a third clutch provided on the intermediate shaft and connected to the third speed change unit to engage or cut off power transmission between the intermediate shaft and the third speed change unit, wherein the hydraulic system is connected to the third clutch to drive the third clutch to engage or disengage, the third speed change unit having a third gear ratio, the second gear ratio being larger than the third gear ratio.

8. The drive system of an electric vehicle according to claim 7, characterized in that the third speed change unit includes a seventh gear provided on the counter shaft and an eighth gear provided on the output shaft and meshed with the seventh gear.

9. The electric vehicle drive system of claim 8, wherein the seventh gear is rotatably journaled on the countershaft, the eighth gear is fixed to the output shaft, a driving portion of the third clutch is fixed to the countershaft, and a driven portion of the third clutch is coupled to the seventh gear.

10. The drive system of an electric vehicle according to claim 7, wherein the second clutch and the third clutch share one active portion.

11. The drive system of an electric vehicle according to claim 7, wherein the first to third clutches are all wet clutches.

12. The drive system of an electric vehicle according to claim 1, characterized in that an axis of the input shaft is collinear with an axis of the output shaft, and an axis of the intermediate shaft is parallel to axes of the input shaft and the output shaft.

13. The drive system of an electric vehicle of claim 1, wherein the hydraulic system further comprises a third one-way valve in parallel with the built-in pump.

14. The drive system of an electric vehicle of claim 13, wherein the hydraulic system further includes first and second filters, the first filter being connected between the inlet ports of the inboard and outboard pumps and the tank, the second filter being connected between the first and second one-way valves and the first and second proportional valves.

15. The electric vehicle drive system of claim 13, wherein the hydraulic system further comprises a relief valve in parallel with the first check valve and the built-in pump in series and the outboard pump and the second check valve in series.

16. The drive system of an electric vehicle of claim 1, wherein the hydraulic system further comprises an accumulator connected between the first and second one-way valves and the first and second proportional valves.

17. The drive system of an electric vehicle of claim 16, wherein the first clutch drive circuit further includes a first snubber connected between the first proportional valve and the first drive cylinder, and the second clutch drive circuit further includes a second snubber connected between the second proportional valve and the second drive cylinder.

18. The drive system of an electric vehicle according to claim 1, characterized in that the hydraulic system further comprises a pressure regulating valve connected in parallel with the built-in pump for supplying the drive system with lubricating oil, and a fourth check valve connected between the pressure regulating valve and an outlet of the built-in pump.