JP2010249185A - Vehicle hydraulic control device - Google Patents

Abstract

A hydraulic control device for a vehicle capable of reliably supplying a necessary amount of oil to a differential mechanism is provided.
This hydraulic control device is applied to a vehicle that transmits a driving force of an internal combustion engine to a driving wheel via a CVT and a differential mechanism, and supplies oil to the CVT as hydraulic oil for changing a gear ratio. On the other hand, an oil pump 32 that supplies oil as lubricating oil to the differential mechanism 16 is provided. The ECU 41 limits the shift speed of the CVT 14 at the upper limit shift speed when the difference in rotational speed between the left and right drive wheels (the differential amount of the differential mechanism 16) exceeds a predetermined rotational speed difference.
[Selection] Figure 2

Description

  The present invention relates to a vehicle that transmits a driving force of an internal combustion engine to drive wheels via a continuously variable transmission and a differential mechanism, and supplies oil to the continuously variable transmission as hydraulic oil for changing a gear ratio. On the other hand, the present invention relates to a vehicle hydraulic control apparatus including an oil pump that supplies oil as lubricating oil to a differential mechanism.

  Conventionally, a belt-type continuously variable transmission (CVT) is known as a transmission mounted on a vehicle (see, for example, Patent Document 1). This belt-type continuously variable transmission includes a first pulley to which a driving force of a driving source is input, a second pulley that outputs a driving force to a pair of driving wheels via a differential mechanism, and the pulleys wound around these pulleys. And first and second hydraulic actuators for changing the widths of the first and second pulleys, respectively. Then, the hydraulic pressure applied from the oil pump to the first and second pulleys is adjusted by the first and second hydraulic actuators, respectively, and the gear ratio is continuously changed by changing the width of each pulley. Yes.

  While changing the transmission ratio of the continuously variable transmission, the transmission speed (transmission time) is increased by increasing the amount of oil per unit time supplied to and discharged from the first and second hydraulic actuators. Conversely, the speed is reduced by decreasing the speed ratio, and the speed ratio is changed at an optimum speed based on the accelerator opening, the vehicle speed, and the like.

JP 2001-330118 A JP 2000-27992 A

  Incidentally, the oil discharged from the oil pump is also supplied to the differential mechanism as lubricating oil for lubrication or cooling (see, for example, Patent Document 2). In general, the oil is supplied to the differential mechanism according to the driving state. For example, the difference in rotational speed between the left and right drive wheels, that is, the amount of oil supplied per unit time when the differential amount is large. On the other hand, when the differential amount is small, the oil amount is reduced. Accordingly, an increase in stirring resistance caused by supplying more oil than necessary is prevented to prevent fuel consumption from deteriorating, and a temperature increase due to stirring is suppressed to prevent oil deterioration.

  Here, for example, when only one of the drive wheels enters the low μ road surface and slip occurs, the differential amount increases, so the amount of oil supplied to the differential mechanism increases. In this state, for example, when the accelerator opening is largely changed by the driver, and the gear ratio of the continuously variable transmission is changed at a high speed (rapid speed change), the unit to be supplied / discharged to each hydraulic actuator The amount of oil per hour will increase. As a result, the flow rate of oil required in the entire hydraulic system exceeds the flow rate that can be supplied by the oil pump, and there is a possibility that the amount of oil supplied to the differential mechanism is insufficient.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle hydraulic control device that can reliably supply a necessary amount of oil to a differential mechanism. is there.

In the following, means for achieving the above object and its effects are described.
According to a first aspect of the present invention, there is provided a vehicle for transmitting a driving force of an internal combustion engine to a driving wheel via a continuously variable transmission and a differential mechanism, wherein oil is used as hydraulic oil for changing a gear ratio. In a hydraulic control apparatus for a vehicle including an oil pump that supplies oil to the differential mechanism as lubricating oil while supplying to the step transmission, the continuously variable transmission is performed when a differential amount of the differential mechanism exceeds a predetermined amount. The gist of the invention is to limit the speed change speed for changing the speed ratio of the machine by a predetermined upper limit value.

  As described above, the continuously variable transmission changes its speed according to the amount of oil per unit time supplied and discharged as hydraulic oil to the continuously variable transmission. The amount of oil supplied to and discharged from the continuously variable transmission per unit time increases. Therefore, in the above configuration, when the differential amount of the differential mechanism exceeds a predetermined amount, the transmission speed of the continuously variable transmission is limited to a predetermined upper limit value, and the gear ratio is changed at the same transmission speed. . By limiting the amount of oil per unit time supplied to the continuously variable transmission in this way, the amount of oil that can be supplied to the differential mechanism can be secured, and the amount required for the differential mechanism It will be possible to reliably supply the oil.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the motive power transmission system of the vehicle by which continuously variable transmission is mounted about one Embodiment of the hydraulic control apparatus of the vehicle concerning this invention. Schematic which shows the hydraulic system of the embodiment. The graph which shows the relationship between the rotational speed difference of a drive wheel, and the oil supply amount to a differential mechanism. The graph which shows the relationship between a transmission speed and the oil supply possible quantity to a differential mechanism. The flowchart which shows the control procedure about the shift speed control by the control apparatus of the embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
An internal combustion engine 11 that generates driving force is mounted on the vehicle, and the internal combustion engine 11 is connected to a CVT 14 via a torque converter 12 and a forward / reverse switching mechanism 13. The forward / reverse switching mechanism 13 switches between forward and backward movement of the vehicle.

  The CVT 14 includes a first pulley 22 provided on the input shaft 21, a second pulley 24 provided on the output shaft 23, and a transmission belt 25 wound around a substantially V-shaped groove in the pulleys 22 and 24. ing. The power is transmitted through a frictional force generated between the transmission belt 25 and the inner wall surfaces of the grooves of the pulleys 22 and 24. Each pulley 22 and 24 is provided with a first hydraulic actuator 27 and a second hydraulic actuator 28 for changing the pulley width, that is, the effective diameter of the transmission belt 25.

The output shaft 23 of the CVT 14 is connected to the pair of left and right drive wheels 17R and 17L via the reduction gear mechanism 15 and the differential mechanism 16.
As shown in FIG. 2, the vehicle controls the amount of oil supplied to and discharged from the first and second hydraulic actuators 27 and 28 as well as lubricating oil to the differential mechanism 16. Is provided with a hydraulic control circuit 31 for controlling the amount of oil supplied. Note that an oil pump 32 that is driven by rotation of the output shaft of the internal combustion engine 11 is connected to the hydraulic pressure control circuit 31. The oil pump 32 sucks oil stored in the oil pan 33 and supplies the oil to the hydraulic control circuit 31.

  The CVT 14 adjusts the hydraulic pressure applied from the oil pump 32 to the pulleys 22 and 24 by the first and second hydraulic actuators 27 and 28, respectively, so that the pulleys of the first pulley 22 and the second pulley 24 are adjusted. The width is continuously changed, and the gear ratio R is changed. Here, the gear ratio R is a value obtained by dividing the rotational speed of the input shaft 21 (hereinafter, input shaft rotational speed Nin) by the rotational speed of the output shaft 23 (hereinafter, output shaft rotational speed Nout). Further, the transmission speed S for changing the transmission gear ratio R is changed according to the amount of oil per unit time supplied / discharged to the first and second hydraulic actuators 27, 28.

  Various controls such as the hydraulic control circuit 31 are performed by an electronic control unit (hereinafter referred to as ECU) 41. The ECU 41 includes a CPU that executes arithmetic processing related to the control of the hydraulic control circuit 31, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores the arithmetic results of the CPU, and external signals. An input port for inputting and an output port for outputting a signal to the outside are provided.

  As shown in FIGS. 1 and 2, detection signals from various sensors provided in the vehicle are input to the input port of the ECU 41. Examples of the various sensors include an input shaft rotational speed sensor 42 that detects an input shaft rotational speed Nin of the CVT 14 and an output shaft rotational speed sensor 43 that detects an output shaft rotational speed Nout. Further, as various sensors, wheel speed sensors 44 and 45 that detect the wheel speeds Vr and Vl of the drive wheels 17R and 17L, an accelerator sensor 47 that detects an accelerator opening ACCP that is a depression amount of the accelerator pedal 46, and a vehicle Examples thereof include a vehicle speed sensor 48 that detects the vehicle speed SPD. The ECU 41 detects the driving state of the vehicle based on the output signals of the various sensors, and performs various controls according to the detected driving state.

  For example, the ECU 41 performs gear ratio control of the CVT 14. Specifically, the gear ratio control is performed based on the accelerator opening ACCP and the vehicle speed SPD by referring to a map stored in advance in the ROM of the ECU 41 so that the target gear ratio Rp that optimizes the fuel consumption characteristics of the vehicle is obtained. The speed ratio R is calculated and controlled so as to become the target speed ratio Rp. At this time, a map set in advance in the ROM of the ECU 41 based on the deviation between the actual speed ratio Rr calculated from the output values of the input shaft speed sensor 42 and the output shaft speed sensor 43 and the target speed ratio Rp. The target shift speed Sp is calculated by referring to it, and the gear ratio R is changed at the target shift speed Sp.

  Further, the ECU 41 controls the amount of oil supplied to the differential mechanism 16. Specifically, the amount of oil (supplied oil amount Fdif) supplied to the differential mechanism 16 is the rotational speed difference ΔW (between the drive wheels 17R and 17L calculated from the output values of the wheel speed sensors 44 and 45 ( When the differential amount is large, the amount of oil supplied per unit time is increased, while when the rotational speed difference ΔW is small, the amount of oil is decreased. Specifically, as shown in FIG. 3, the supply oil amount Fdif is set to the low load oil amount A1 when the rotational speed difference ΔW is smaller than the predetermined rotational speed difference ΔWth, while the rotational speed difference ΔW is predetermined. When the rotational speed difference is greater than or equal to ΔWth, the oil amount for high load A2 is set.

  By the way, the transmission speed S for changing the transmission gear ratio R is increased by increasing the amount of oil per unit time supplied to and discharged from the first and second hydraulic actuators 27 and 28, but is decreased on the contrary. It will be late. Therefore, as shown in FIG. 4, the amount of oil (suppliable amount Fa) that can be supplied to the differential mechanism 16 by the oil pump 32 decreases as the transmission speed S increases.

  Here, for example, when only the drive wheel 17R enters the low μ road surface and slip occurs, the rotational speed difference ΔW increases, so that the amount of oil Fdif supplied to the differential mechanism 16 is high-load oil. The amount becomes A2. In this state, when the transmission gear ratio is changed at a high transmission speed S, the amount of oil required for the transmission increases, so that the oil flow rate required for the entire hydraulic system of the vehicle is increased by the oil pump 32. There is a possibility that the amount of oil supplied to the differential mechanism 16 is insufficient because the flow rate that can be supplied is exceeded.

  Therefore, the ECU 41 according to the present embodiment can supply oil of the high load oil amount A2 to the differential mechanism 16 by the oil pump 32 when the rotational speed difference ΔW of the differential mechanism 16 exceeds the predetermined rotational speed difference ΔWth. The transmission speed S of the CVT 14 is limited at the upper limit transmission speed Slim.

  Next, the processing procedure of the shift speed control by the ECU 41 of the present embodiment will be described according to the flowchart shown in FIG. A series of processes shown in the flowchart of FIG. 5 is repeatedly executed at a predetermined cycle by the ECU 41 immediately after the internal combustion engine 11 is started.

  When this process is started, first, the driving state of the vehicle is read through the detection signals of the various sensors (step S1), and then the target shift speed Sp is calculated (step S2). Subsequently, it is determined whether or not the rotational speed difference ΔW is larger than the predetermined rotational speed difference ΔWth (step S3). If the rotational speed difference ΔW is equal to or smaller than the predetermined rotational speed difference ΔWth (step S3: NO), the difference is determined. The supply oil amount Fdif to the moving mechanism 16 is set to the low load oil amount A1 (step S4), and this process is temporarily ended.

  On the other hand, when the rotational speed difference ΔW is larger than the predetermined rotational speed difference ΔWth (step S3: YES), the oil amount Fdif supplied to the differential mechanism 16 is set to the high load oil amount A2 (step S5). . Subsequently, it is determined whether or not the target shift speed Sp calculated in step S2 is higher than the upper limit shift speed Slim (step S6). If the target shift speed Sp is higher than the upper limit shift speed Slim (step S6) (S6: YES), the transmission gear ratio R is changed at the upper limit transmission speed Slim (step S7). When the target shift speed Sp is equal to or lower than the upper limit shift speed Slim (step S6: NO), the gear ratio R is changed while keeping the target shift speed Sp (step S8).

As described above, according to the present embodiment, the following operational effects can be obtained.
(1) In the present embodiment, when it is necessary to supply a large amount (high load oil amount A2) of oil to the differential mechanism 16, the transmission speed S of the transmission ratio R of the CVT 14 is limited by the upper limit transmission speed Slim. By doing so, the amount of oil per unit time supplied to and discharged from the first and second hydraulic actuators 27 and 28 is limited. As a result, the oil supplyable amount Fa to the differential mechanism 16 can be secured, and a necessary amount of oil can be reliably supplied to the differential mechanism 16.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
In the above embodiment, when the rotational speed difference ΔW of the differential mechanism 16 exceeds the predetermined rotational speed difference ΔWth, the oil pump 32 can supply the high load oil amount A2 to the differential mechanism 16 by the oil pump 32. Although the shift speed S of the CVT 14 is limited at the speed Slim, the present invention is not limited to this. When the rotational speed difference ΔW of the differential mechanism 16 exceeds the predetermined rotational speed difference ΔWth, the supplyable amount Fa to the differential mechanism 16 by the oil pump 32 is sufficiently larger than the low load oil amount A1. It may be smaller than the high load oil amount A2.

  In the above embodiment, for example, as the difference (ΔW−ΔWth) between the rotational speed difference ΔW and the predetermined rotational speed difference ΔWth increases, the amount of oil supplied to the differential mechanism 16 is increased while the speed of the CVT 14 is limited. It is also possible to employ a configuration in which the upper limit speed change speed Slim is reduced. Even with such a configuration, it is possible to achieve the operational effects according to the above embodiment (1).

  DESCRIPTION OF SYMBOLS 11 ... Internal combustion engine, 12 ... Torque converter, 13 ... Forward / reverse switching mechanism, 14 ... CVT, 15 ... Reduction gear mechanism, 16 ... Differential mechanism, 17L, 17R ... Drive wheel, 21 ... Input shaft, 22 ... First pulley , 23 ... output shaft, 24 ... second pulley, 25 ... transmission belt, 27 ... first hydraulic actuator, 28 ... second hydraulic actuator, 31 ... hydraulic control circuit, 32 ... oil pump, 33 ... oil pan, 41 ... ECU (Electronic control device) 42... Input shaft rotation speed sensor 43... Output shaft rotation speed sensor 44 44 45 Wheel speed sensor 46 accelerator pedal 47 47 accelerator sensor 48 vehicle speed sensor

Claims (1)

In a vehicle that transmits a driving force of an internal combustion engine to a drive wheel via a continuously variable transmission and a differential mechanism, oil is supplied to the continuously variable transmission as hydraulic oil for changing a gear ratio, In a vehicle hydraulic control device including an oil pump that supplies oil as lubricating oil to a differential mechanism,
A vehicle hydraulic control device characterized by limiting a shift speed for changing a gear ratio of the continuously variable transmission with a predetermined upper limit value when a differential amount of the differential mechanism exceeds a predetermined amount.

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