JP2007045230A - Driving force control device at the time of starting over a step of a hybrid vehicle - Google Patents

Abstract

The present invention proposes a driving force control capable of suppressing a sudden increase in vehicle speed when a running resistance is lowered at the end of stepping over at a start without depending on a driver's accelerator operation.
When an accelerator opening APO is increased from t0 as shown in the figure in a state where a step causing a running resistance R = R2 is encountered, the driving torque T is also increased as shown. The vehicle speed VSP rises as indicated by the solid line due to the generation of the marginal driving force (T−R) from t1 when T becomes the torque Tb that balances the running resistance R2, and the step over the step is started. After t2 when the step overstep is completed and R decreases from R2 to R1, T is kept large as indicated by the solid line and the wavy line sequentially corresponding to APO. After increasing rapidly as shown by the solid line and the wavy line, it is kept at a large value. Due to such marginal driving force, the vehicle speed VSP rapidly increases as indicated by solid lines and wavy lines. In order to prevent this, T is decreased from the wavy line to the solid line after the time t3 when the step overstep is determined, and the increase in the vehicle speed VSP is suppressed from the wavy line to the solid line.
[Selection] Figure 3

Description

  The present invention includes a motor in addition to an engine as a power source, and a hybrid vehicle that is driven by power from at least one of the engine and the motor starts over the step and starts over the step, immediately after the step over the step is finished. The present invention relates to an apparatus for appropriately controlling the driving force of a hybrid vehicle.

The vehicle is not limited to a hybrid vehicle, and it may be necessary to start the vehicle while overcoming a step at the time of starting.
Thus, when starting the vehicle while overcoming the step, control is required to increase the driving force so as to be able to get over the step in order to make it possible to get over the step.

  In a vehicle equipped with an automatic transmission in which the engine rotation is input to the automatic transmission through the torque converter, and the automatic transmission shifts the input rotation and directs it to the drive wheels, the driver will When the engine speed (torque converter input speed) is increased by depressing the pedal, the torque converter generates a torque increasing action and easily starts over the step, so the driver does not depress the accelerator pedal greatly. You can start over steps.

  Also, when the driver depresses the accelerator pedal at the end of stepping over and decreases the engine speed (torque converter input speed), the torque converter does not increase the torque, so the running resistance decreases at the end of stepping over the step. Therefore, it is possible to easily prevent the vehicle from protruding when the vehicle speed rapidly increases.

For vehicles equipped with automatic transmissions, as described above, it is not necessary for the driver to depress the accelerator pedal significantly when starting over the step, and the engine rotation decreases due to the accelerator pedal being depressed when the step is over. Since the torque increasing action of the torque converter is canceled and the vehicle sticking out prevention effect can be expected,
When the accelerator pedal is stepped back in order to avoid a sudden increase in vehicle resistance due to a decrease in running resistance at the end of stepping over the step, the return amount is small and the return speed may be relatively slow.

By the way, the hybrid vehicle to be controlled by the present invention includes a motor in addition to the engine as a power source, as represented by the one described in Patent Document 1, and the power from at least one of these engines and motors. However, it is common practice to follow a configuration in which the torque converter is not included in the transmission system with a mission of high transmission efficiency.
Japanese Patent No. 3045063

  However, in a hybrid vehicle that does not include a torque converter in the transmission system, it is impossible to expect stepping over a step using the torque increase function of the torque converter caused by the increase in engine rotation accompanying the depression of the accelerator pedal. Therefore, the driver makes the accelerator pedal depression amount larger than that of the vehicle equipped with the automatic transmission when starting over the step.

  In such a hybrid vehicle, since the accelerator pedal depression amount is increased at the time of starting over the step, the vehicle speed suddenly rises and the vehicle sticks out when the running resistance decreases at the end of overcoming the step In order to prevent this, the driver must hurry up and greatly depress the accelerator pedal, resulting in a problem that the driving operability at the end of overcoming the step is deteriorated.

As shown in FIG. 3, in the state where the wheel encounters a step that causes the running resistance R = R2, the vehicle is stepped over the step by increasing the accelerator opening APO as shown in FIG. The problem is detailed.
As the accelerator opening APO increases, the drive torque T also increases as shown in the figure.
If there is no step, the vehicle speed VSP rises from the instant t0 as shown by the two-dot chain line, but because there is a step, the vehicle speed VSP is not driven enough until the driving torque T becomes the torque Tb that balances the running resistance R2. When the force (driving torque T−running resistance R) is generated, the vehicle rises as shown by the solid line and starts to climb over the step.

Even after the instant t2 when the travel resistance R decreases from R2 to R1 after overcoming the step, the driving torque T is kept large as shown by the solid line and the wavy line sequentially due to the large accelerator opening APO. As the running resistance R decreases, the marginal driving force increases rapidly as indicated by the solid line and the dashed line, and then is maintained at a large value.
The vehicle speed VSP suddenly increases as indicated by the solid line and the wavy line due to the sudden increase in the marginal driving force and the high stop, and the vehicle tends to feel like being pushed out at the end of overcoming the step.
In order to eliminate this sticking out feeling, the driver needs to hurry up and greatly depress the accelerator pedal, which causes deterioration in driving operability at the end of stepping over the step.

  The present invention drives at the start of stepping over a step that does not cause the vehicle to stick out even if the driver does not perform a special accelerator operation to depress the accelerator pedal in a hurry at the end of stepping over the step. The purpose is to propose force control, and to solve the problem related to the deterioration of the driving operability at the time of overcoming the step.

For this purpose, the driving force control device at the start of overcoming the step of the hybrid vehicle according to the present invention, as described in claim 1,
It is based on a hybrid vehicle that includes an engine and a motor as a power source and is driven by power from at least one of the engine and motor.
Stepped over end detection means for determining that the wheel has gone over the step from the vehicle speed information related to the vehicle speed at the start of the vehicle,
This means comprises a driving force suppressing means for suppressing the driving force when the step overstep determination is made.

According to the driving force control device at the time of starting over the step of the hybrid vehicle according to the present invention, the driving force is suppressed when detecting that the step over has been completed.
Because the hybrid vehicle does not have a torque converter in the transmission system, the required driving force, which is the difference between the driving force and the running resistance at the end of stepping over the step where the running resistance is reduced, even if the accelerator pedal is greatly depressed when starting over the step Without being kept large, a large increase in the vehicle speed (feeling of vehicle protrusion) due to this extra driving force can be mitigated.

  The above-mentioned effects can be sold without the driver having to perform a special accelerator operation that depresses the accelerator pedal in a hurry at the end of step climbing, and the above-described deterioration in driving operability at the end of step climbing has been described. The problem can be solved.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a front engine / front wheel drive type (front wheel drive type) hybrid vehicle provided with a driving force control device for starting over a step according to an embodiment of the present invention, along with its control system.

This power train includes an engine 1 and a motor 2 as power sources, and drives the vehicle by driving the left and right front wheels 3 as described later with the power from these.
For this reason, a differential device that enables the simple planetary gear set 4 is provided. The simple planetary gear set 4 includes a sun gear 4s, a ring gear 4r, and a carrier 4c that rotatably supports a plurality of pinions 4p engaged with the sun gear 4s. Consists of.

The input shaft 5 is coupled to the carrier 4c, the engine 1 is coupled to the input shaft 5, and the engine rotation is input to the carrier 4c.
Engine rotation to the carrier 4c is transmitted to the generator (generator) 7 through the sun gear 4s and the hollow shaft 6 rotating on the input shaft 5 on the one hand, and the ring gear 4r, sprocket 8, chain 9 and final deceleration on the other hand Transmission is made to the left and right front wheels 3 via the machine 10 and the differential gear device 11.

  The motor 2 is further coupled to the ring gear 4r, and the rotation from the motor 2 is also transmitted to the left and right front wheels 3 via the ring gear 4r, the sprocket 8, the chain 9, the final reduction gear 10, and the differential gear device 11.

  In the power train of the hybrid vehicle having the configuration shown in FIG. 1, the power of the engine 1 is transmitted from the input shaft 5 through the carrier 4c, the ring gear 4r, the sprocket 8, the chain 9, the final reduction gear 10, and the differential gear device 11, and , The power of the motor 2 can be transmitted from the ring gear 4r to the left and right front wheels 3 via the sprocket 8, the chain 9, the final reduction gear 10, and the differential gear device 11, and / or in cooperation with the engine 1 and the motor 2. The vehicle can be driven by either one.

During this time, the generator 7 is operated by a part of the engine power to generate electric power corresponding to the power generation load, and the motor 2 is driven by this electric power and electric power from the battery 12 to be applied as necessary. .
When the vehicle starts, the engine 1 is stopped, and only the power from the motor 2 is transmitted from the ring gear 4r to the left and right front wheels 3 via the sprocket 8, the chain 9, the final reduction gear 10, and the differential gear device 11, The start shall be made.

The engine 1, the motor 2, and the generator 7 are controlled by the integrated controller 13, and for this reason, the integrated controller 13
A signal from an accelerator opening sensor 14 for detecting an accelerator pedal depression amount (accelerator opening APO) representing a required load state of the engine 1;
A signal from the engine speed sensor 15 for detecting the engine speed Ne;
A signal from the vehicle speed sensor 16 for detecting the vehicle speed VSP;
A signal from the storage state sensor 17 for detecting the storage state SOC (carryable power) of the battery 12,
A signal from a driving torque sensor 18 that detects a driving torque (driving force) T of the front wheel 3 is input.

The integrated controller 13 determines the target engine torque tTe, the target motor torque tTm, and the power generation load tTg by a known calculation based on these input information.
The target engine torque tTe is supplied to the engine controller 19, and the engine controller 19 controls the engine 1 so that the engine torque becomes the target engine torque tTe.
The target motor torque tTm and the power generation load tTg are supplied to the motor / generator controller 20.

Here, the motor / generator controller 20 supplies the power generation load tTg to the generator 7 so that the generator 7 generates power corresponding to the power generation load tTg and directs the power to the motor 2 via the inverter 21. Or charge the battery 12
On the other hand, the electric power from the generator 7 and / or the electric power from the battery 12 is supplied to the motor 2 via the inverter 21 so that the torque of the motor 2 becomes the target motor torque tTm.

In addition to the above-described normal control, the integrated controller 13 executes the control program shown in FIG. 2 and performs the driving force control at the time of starting over the step intended by the present invention as follows.
In the control program of FIG. 2, the driving torque T becomes a torque Tb that balances the running resistance R2 as at the instant t1 in FIG. 3, and the vehicle speed VSP is represented by a solid line due to the generation of a marginal driving force (driving torque T−running resistance R). As shown, it starts and starts at the instant t1 when the step over is started.
Here, the start of stepping over the step can be detected with the rise of the vehicle speed VSP.

First, in step S1, the vehicle speed VSP = 0 at the step overstep start instant t1 in FIG. 3 is stored as the initial vehicle speed value.
In the next step S2, the driving torque T = Tb at the step overtaking start instant t1 in FIG. 3 is stored as the initial torque value.
Next, at step S3, the vehicle speed VSP at the time t2 when the step overstep is finished is set to VSP1, and the vehicle speed VSP at the instant t3 when the driving force control intended by the present invention is started is set to VSP2.

Here, the determination of the completion of overstepping can be made when the moving average of the wheel angular acceleration becomes equal to or greater than a set value.
The instant t3 at which the driving force control is started is the time when the minimum time Δt ′ necessary for obtaining the vehicle acceleration α ′ thereafter elapses from the time t2 when the step overstep determination is completed.

In step S5, the vehicle acceleration α ′ after the step t2 at the end of overstepping is set to α ′ = (VSP2−VSP1) / Δt ′.
= ΔV '/ Δt'
The vehicle acceleration α before the step over end t2 is calculated as α = (VSP1−0) / Δt using the time Δt from the step overstep start t1 to the step over end determination time t2.
= ΔV / Δt
Calculated by
Using these calculation results, the acceleration change (α′−α) before and after overcoming the step is calculated.

In the next step S6, a torque change (T′−Tb) before and after overcoming the step is calculated.
In step S7, a ratio X = (α′−α) / (T′−Tb) of acceleration change (α′−α) with respect to torque change (T′−Tb) before and after overcoming the step is obtained and set. It is determined whether or not the value Y has been exceeded.
When the acceleration change ratio X with respect to the torque change before and after stepping over the step is larger than the set value Y, the acceleration change (α′−α) with respect to the torque change (T′−Tb) before and after stepping over the step. ) Is large, the step over the step has been completed, and the step over the step that causes the above-mentioned protruding feeling of the vehicle is generated.

While it is determined in step S7 that the acceleration change ratio X with respect to the torque change before and after stepping is less than the set value Y, the driving force control at the start of stepping over the step according to the present invention is unnecessary, so the control is returned to step S3. Repeat the above loop.
When it is determined in step S7 that the acceleration change ratio X with respect to the torque change before and after stepping exceeds the set value Y, the driving force at the start of stepping over the step according to the present invention at the end of stepping over that causes the above-described vehicle protrusion feeling. Since control is required, the control proceeds to step S8 and subsequent steps.
Therefore, step S7 corresponds to the step overcoming detection means in the present invention.

In step S8, as seen after the instant t3 in FIG. 3, the drive torque T is reduced from the torque value shown by the wavy line to the torque value shown by the solid line in accordance with the acceleration change rate X with respect to the torque change before and after stepping over the step. Let
The integrated controller 13 outputs the target motor torque tTm to the motor / generator controller 20 so that the decrease of the driving torque T is achieved.

As a result, the marginal driving force decreases from the value shown in the wavy line as indicated by the solid line after the instant t3 in FIG. It is possible to alleviate the feeling of vehicle protrusion.
Further, as is apparent from the time series change shown in FIG. 3 of the accelerator opening APO, the above-mentioned effects can be achieved without the driver performing a special accelerator operation that rapidly depresses the accelerator pedal. Thus, it is possible to solve the conventional problem that the driving operability at the end of overcoming the step is deteriorated.
Therefore, step S8 corresponds to the driving force suppressing means in the present invention.

In step S9, the driving torque T ′ at t3 when it is determined that the step overstep is over is stored,
In step S10, it is checked whether or not the acceleration change rate X is larger than the second set value Z (however, Z> Y), and the above problem can be solved only by reducing the drive torque in step S8. It is determined whether or not it is possible to get over a step that cannot be done.

If the above problem can be solved only by reducing the driving torque in step S8, the process proceeds to step S12 by skipping step S11, but if the above problem solving cannot be realized only by reducing the driving torque. In step S11, automatic brake control is executed so that the vehicle deceleration according to the acceleration change rate X is achieved. Even in such a case, the vehicle can be reliably projected after the step over the step without any special accelerator operation. To be able to relax.
Therefore, step S10 and step S11 also correspond to the driving force suppressing means in the present invention.

In step S12, it is determined whether or not the driver has performed a brake operation or an accelerator operation after t3 at the time when the step overstep determination is completed. Determine whether.
If none of these conditions are satisfied, the control is returned to step S3 and the above loop is repeatedly executed. When any one of the conditions is satisfied, the control is executed to end the driving force control. Proceeding to S13 avoids the adverse effect that the above driving force control is performed indefinitely.

In step S13, the drive torque T, which has been reduced as described above, is gradually increased and returned to the drive operation request drive torque corresponding to the accelerator opening APO,
The integrated controller 13 outputs the target motor torque tTm to the motor / generator controller 20 so that the increase return of the driving torque T is achieved.
Thereby, the increase return of the driving torque T can be smoothly performed without a shock.
Therefore, step S12 and step S13 also correspond to the driving force suppressing means in the present invention.

In step S14, it is determined whether or not the vehicle has traveled a distance corresponding to the wheel base after finishing over the step, that is, the vehicle has traveled a distance corresponding to the wheel base from when the preceding wheel in front of the vehicle travels over the step. Then, it is checked whether or not the subsequent wheels at the rear of the vehicle traveling direction have encountered the same step.
While it is determined in step S14 that the subsequent wheels have not yet encountered the same step, control is returned to step S3 and the above loop is repeated.

When it is determined in step S14 that the following wheels have encountered the same step, the drive torque T is increased in step S15 to the drive torque T ′ at the end of step climbing stored in step S9.
The integrated controller 13 outputs to the motor / generator controller 20 a target motor torque tTm that achieves an increase in the driving torque T.
As a result, when the succeeding wheel gets over the same step, the driving force is not insufficient, and the step can be reliably overcome without the driver depressing the accelerator pedal (increasing the accelerator opening APO).
Accordingly, step S14 corresponds to the subsequent wheel level difference encounter detecting means in the present invention, and step S15 corresponds to the driving force increasing means in the present invention.

  In the final step S16, the determination of the end of the step over the step of the following wheel is performed in the same manner as the determination of the end of the step over of the preceding wheel, and after this determination, the same driving force control as that when the determination of the end of step over of the preceding wheel is made is made. To achieve the same effect as described above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic perspective view showing a power train of a hybrid vehicle having a driving force control device for starting over a step according to an embodiment of the present invention together with its control system. It is a flowchart which shows the driving force control program at the time of starting over a level | step difference which the integrated controller in the same control system performs. FIG. 3 is an operation time chart when the driving force control at the time of starting over a step in FIG. 2 is performed. FIG.

Explanation of symbols

1 Engine 2 Motor 3 Front Wheel (Drive Wheel)
4 Simple planetary gear set 5 Input shaft 6 Hollow shaft 7 Generator 8 Sprocket 9 Chain
10 Final reduction gear
11 Differential gear unit
12 battery
13 Integrated controller
14 Accelerator position sensor
15 Engine rotation sensor
16 Vehicle speed sensor
17 Battery charge state sensor
18 Drive torque sensor
19 Engine controller
20 Motor / generator controller
21 Inverter

Claims (6)

In a hybrid vehicle including an engine and a motor as a power source and driven by power from at least one of the engine and motor,
Stepped over end detection means for determining that the wheel has gone over the step from the vehicle speed information related to the vehicle speed at the start of the vehicle,
A driving force control device at the time of starting over a step of a hybrid vehicle, characterized in that it comprises driving force suppressing means for suppressing driving force when it is determined that the step overstep is completed. In the driving force control device at the start of overcoming the step of the hybrid vehicle according to claim 1,
The step climbing end detection means obtains acceleration information from the vehicle speed information, and determines that the step climbing has ended when the acceleration information indicates a sudden increase in acceleration exceeding a set value. Driving force control device at the start of overcoming a step in a hybrid vehicle. In the driving force control device at the start of overcoming the step of the hybrid vehicle according to claim 2,
The driving force suppression means has a second set value in which the difference between the acceleration information before and after the step overstep end determination is made by the step overstep end detection means is larger than the set value for the step over end determination. A driving force control device at the time of starting over a step of a hybrid vehicle, wherein the driving force is suppressed also by braking of a wheel when the difference indicates a sudden increase in acceleration. In the driving force control device at the start of overcoming the step of the hybrid vehicle according to any one of claims 1 to 3,
The driving force suppression means is after a set time has elapsed from when the step overstep detection is determined by the step over end detection means, after a set distance has elapsed, or when there is a braking operation or an accelerator operation by the driver, A driving force control apparatus for starting over a step of a hybrid vehicle, characterized in that the suppression of the driving force is terminated. In the driving force control device at the start of overcoming the step of the hybrid vehicle according to any one of claims 1 to 4,
The step of the hybrid vehicle is characterized in that the driving force suppression means gradually increases and returns the driving force to the driving operation request driving force corresponding to the accelerator operation state when the driving force suppression ends. Driving force control device when getting over. In the driving force control device at the start of overcoming the step of the hybrid vehicle according to any one of claims 1 to 5,
Subsequent wheel step encounter detection means for determining that the subsequent wheel at the rear of the vehicle traveling direction encounters the same step when the preceding wheel in the vehicle traveling direction has traveled a distance corresponding to the wheel base from when the preceding wheel has climbed over the step,
A driving force control device at the time of starting overcoming a step of a hybrid vehicle, comprising: driving force increasing means for increasing the driving force when it is determined that the following wheel encounters the step by this means.

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