JPS629065A - Device for controlling hydraulic pressure for stepless transmission for vehicle - Google Patents

Abstract

PURPOSE:To improve the efficiency of fuel consumption by varying the velocity ratio of a stepless transmission in accordance with the slope of a traveling road. CONSTITUTION:The velocity ratio varying speed of a belt-type stepless transmission 14 is varied in accordance with the slope of a traveling road. Therefore, on a traveling road having curves and, furthermore, upward and downward slopes, the width of variation in a velocity ratio as a whole becomes small. Accordingly, the operation of an accelerator pedal can be made easier while favorably improving the drivability of a vehicle and the efficiency of fuel consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a hydraulic control system for a continuously variable transmission for a vehicle, and more particularly to a technique for improving drivability on an uphill or downhill road with many curves.

Conventional technology Continuously variable transmissions for vehicles that steplessly change the speed of the engine's rotation and transmit it to the driving wheels are known.Vehicles equipped with such continuously variable transmissions have high engine fuel efficiency when driving. Since the driving conditions can be selected, higher fuel consumption efficiency can be achieved compared to vehicles equipped with conventional stepped transmissions, and
Since the speed ratio (output shaft rotation speed/input shaft rotation speed) can be changed steplessly, there is an advantage that no shift shock occurs. Many control devices for controlling the speed ratio of such continuously variable transmissions for vehicles have been proposed in the past, and their basics are, for example, controlling the driver's intention to perform acceleration/deceleration operations, such as the amount of accelerator operation. A target rotational speed or target speed ratio is determined from a predetermined relationship in order to obtain the optimum fuel efficiency rate based on the expressed quantity, and the target rotational speed or target speed ratio is compared with the actual input shaft rotational speed or speed of the continuously variable transmission. It is controlled so that the ratio matches the ratio. In a control device for such a continuously variable transmission, a predetermined change rate is generally set so that the actual input shaft rotational speed or speed ratio matches the target value, taking into account fuel efficiency and drivability mainly on flat roads. It can be changed by.

In such conventional control devices, the change speed of the continuously variable transmission is also set mainly on flat roads, so the acceleration response of the vehicle is poor on driving roads with many curves and slopes, such as mountain roads. In some cases, sufficient drivability could not be obtained.

In response to this, proposals have been made such as a technique for applying engine braking when the vehicle is dismounting (Japanese Patent Application Laid-open No. 191359-1982) and a technique for reducing the target speed ratio when the vehicle is climbing up the platform (Japanese Patent Laid-Open No. 180864-1986). has been done.

Problems to be Solved by the Invention However, even with such conventional technology, when driving on a road with many curves, such as a mountain road, and many uphill and downhill slopes, it is necessary to frequently repeat acceleration and deceleration operations. In this case, the problem is not the correction of the target speed ratio but the speed ratio change speed at which the speed ratio is changed. That is, when driving on a road with curves, the driver usually releases the accelerator pedal when the vehicle approaches the curve. In this case, the speed ratio is changed relatively quickly in the direction of a larger speed ratio at a change speed determined assuming a flat road, but by the time the next uphill drive starts, the speed ratio has become quite large. The driving force is insufficient, and the driver has to operate the accelerator pedal greatly. Further, after the above-mentioned point in time, the rate of change in the direction of reducing the speed ratio is too slow if the value is set assuming a flat road, so the throttle opening must be kept large. On the other hand, when exiting a curved exit road, a driver normally performs an acceleration operation to compensate for deceleration at the curve. At this time, for the same reason as in the above case, the speed ratio becomes too small than necessary, and the accelerator pedal must be released when the vehicle enters steady running. Therefore, with conventional control devices, the range of change in speed ratio becomes unnecessarily large, so the accelerator pedal must be operated frequently on driving roads with many curves and many uphill and downhill slopes, such as mountain roads. Drivability deteriorated, and sufficient fuel consumption efficiency could not be obtained.

Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is to provide a vehicle engine that continuously changes the speed of the engine and transmits it to the drive wheels. In a gear transmission,
A hydraulic control device that adjusts the speed ratio of the continuously variable transmission by supplying hydraulic oil to a hydraulic actuator that changes the speed ratio of the continuously variable transmission or discharging the hydraulic oil in the hydraulic actuator, the hydraulic control device controlling the speed ratio of the continuously variable transmission. Provided in at least one of an oil supply path and a hydraulic oil discharge path from the hydraulic actuator, and changes the flow rate in at least one of the hydraulic oil supply path and the hydraulic oil discharge path in response to the running road gradient of the vehicle. By this,
The present invention includes a variable throttle valve device that changes the speed ratio change speed of the continuously variable transmission in accordance with the road gradient.

Operation and Effects of the Invention With this structure, the hydraulic control device changes the flow rate in at least one of the hydraulic oil supply path and the hydraulic oil discharge path in response to the slope of the traveling road of the vehicle.
Since it includes a variable throttle valve device that changes the speed ratio change speed of the continuously variable transmission according to the gradient of the road the vehicle is running on, it can be optimized according to the gradient of the road on a road with curves and uphill and downhill slopes. The speed ratio of the continuously variable transmission is changed at a change speed of . Therefore, the range of change in the speed ratio becomes smaller as a whole, the accelerator pedal operation is reduced, and the drivability and fuel consumption efficiency of the vehicle are suitably improved.

The variable throttle valve device is preferably provided in at least one of a hydraulic oil supply path to the hydraulic actuator and a hydraulic oil discharge path from the hydraulic actuator. The vehicle is configured to include a throttle valve that changes the flow rate of the vehicle, and a gradient sensing portion having a weight that moves to drive the throttle valve in response to the gradient of the road the vehicle travels on.

Preferably, the throttle valve is provided with a spool that is movable in the axial direction, and the weight of the gradient sensing section is preferably provided that is movable in the longitudinal direction of the vehicle. The spool is configured to be driven by moving according to the inclination.

Further, the gradient sensing section preferably includes a braking means for suppressing the weight from moving in accordance with sudden acceleration or deceleration of the vehicle.

Preferably, the continuously variable transmission is equipped with a pair of variable pulleys having variable effective diameters and a transmission belt wound between the variable pulleys, and the hydraulic actuator is a belt-type transmission belt. The variable throttle valve device changes the effective diameter of the input side variable pulley of the continuously variable transmission, and the variable throttle valve device reduces the flow rate of the hydraulic oil supply path as the running road gradient of the vehicle becomes more positive. It is configured to increase the flow rate of the hydraulic oil discharge path, and conversely, the more negative the running road slope, the larger the flow rate of the hydraulic oil supply path and the smaller the flow rate of the hydraulic oil discharge path. .

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, a belt type continuously variable transmission 14 is connected to an engine 10 via a clutch 12 such as a magnetic particle type electromagnetic clutch or a centrifugal clutch, and the rotation of the engine 10 is controlled by the belt type continuously variable transmission 14. After being shifted to the stage,
The signal is transmitted to the drive wheels via a differential reducer (not shown) or the like.

The belt type continuously variable transmission 14 includes an input shaft 16 connected to the clutch 12, a variable pulley 18 with a variable effective diameter attached to the input shaft 16, an output shaft 20, and an output shaft 20.
A variable pulley 22 with a variable effective diameter attached to the
4, and hydraulic cylinders 26 and 28 that change the V-groove width of the variable pulleys 18 and 22 to change the effective diameter. The variable pulleys 18 and 22 are connected to the input shaft 1, respectively.
6 and the fixed rotating bodies 30 and 32 fixed to the output shaft 20, and the fixed rotating bodies 30 and 32 respectively attached to the input shaft 16 and the output shaft 20 so as to be movable in the axial direction and non-rotatable about the axis. The movable rotary bodies 34 and 36 form V grooves in the hydraulic cylinders 26 and 28, respectively, and the movable rotary bodies 34 and 36 are driven in the axial direction by hydraulic pressure applied to the spaces within the hydraulic cylinders 26 and 28. The belt diameter (effective diameter) of the belt 24 can be changed continuously. Line hydraulic pressure is constantly supplied to the hydraulic cylinder 28, and the amount of hydraulic oil (hydraulic pressure) in the hydraulic cylinder 26 is adjusted by a speed ratio control valve 38, thereby acting on the movable rotating bodies 34 and 36. The balance of forces is changed to change the speed ratio of the input shaft 16 and output shaft 20 of the continuously variable transmission.

The line oil pressure is obtained by regulating the pressure of hydraulic oil pumped from the oil tank 40 by the pump 42 by the line oil pressure regulating valve 44, and is supplied to the speed ratio control valve 38 and the hydraulic cylinder 28 via the line oil passage 46. ing. The line hydraulic pressure regulating valve 44 includes a linear solenoid driven by a pressure regulating signal SP, which will be described later, and a valve element driven by the linear solenoid, and serves as a relief valve for hydraulic oil pumped from the pump 42 to the oil tank 40. The line oil pressure is regulated by changing it according to the pressure regulation signal sp. The speed ratio control valve 38 is composed of an inflow side flow rate control servo valve 38A and an outflow side flow rate control servo valve 38B, and these servo valves 38A and 38B are driven by a linear solenoid and its and valves each driven by a linear solenoid. The inflow side flow rate control servo valve 38A adjusts the amount of hydraulic oil flowing into the hydraulic cylinder 26 by communicating the oil passage 48 communicating with the hydraulic cylinder 26 with the line oil passage 46 and changing the flow area thereof. On the other hand, the outflow side flow rate control servo valve 38B adjusts the amount of hydraulic oil discharged from the hydraulic cylinder 26 by communicating the oil passage 48 and the return oil passage 50 to the oil tank 40 and changing the flow area thereof. That is, communication between the oil passage 48, the line oil passage 46, and the oil passage 50 is cut off by the inflow side flow rate control servo valve 38A and the outflow side flow rate control servo valve 38B, respectively, so that the amount of hydraulic oil in the hydraulic cylinder 26 is kept constant. In the state where the oil passage 48 and the line oil passage 46 are communicated with each other by the inflow side flow rate control servo valve 38A, the amount of hydraulic oil in the hydraulic cylinder 26 is increased. Therefore, the effective diameter of the variable pulley 18 is increased and the effective diameter of the variable pulley 22 is decreased, so that the speed ratio signal S8
The speed ratio is increased at a rate of change depending on the magnitude of 1. On the contrary, when the oil passage 48 and the return oil passage 50 are brought into communication by the outflow side flow rate control servo valve 38B, the speed ratio is decreased at a rate of change depending on the magnitude of the speed ratio signal SS2.

A throttle valve 5 is provided in the intake pipe of the engine 10 and is opened and closed in conjunction with the operation of the accelerator pedal 52.
4 is attached to the throttle valve 54, and a throttle signal TH, which is a voltage corresponding to the opening degree θT)I of the throttle valve 54, is supplied to the microcomputer 58 by a throttle sensor 56 attached to the throttle valve 54. The vehicle also includes an inclinometer 60 for detecting the slope of the running road surface.
is provided, and a slope signal SK representing the running road surface slope θ is provided.
is supplied to the microcomputer 58. The input shaft 16 and the output shaft 20 are provided with rotation sensors 62 and 64, respectively, for detecting their rotational speeds.
Pulse rotation signals Sl and SO corresponding to the rotations of the output shaft 20 and the output shaft 20 are supplied to the microcomputer 58, respectively.

The microcomputer 58 includes a CPU and a RAM.

Equipped with a ROM, an A/D converter, an interface, etc., the CPU processes the input signal supplied while utilizing the memory function of the RAM according to the program stored in advance in the ROM, and matches the actual speed ratio with the target speed ratio. It outputs speed ratio signals SSI and SS2 to the flow rate control servo valves 38A and 38B, and outputs a pressure regulation signal SP indicating the pressure of the line oil pressure to the line oil pressure regulation valve 44. The speed ratio signals SSI and SS2 are voltage signals representing the speed ratio change direction and speed ratio change speed, respectively, and are determined so that the fuel efficiency and drivability are optimized based on the relationship in which the actual speed ratio is determined in advance. It is set to "0" when the speed ratio matches the target speed ratio. Further, the pressure regulation signal SP supplied to the line hydraulic pressure regulating valve 44 is determined based on the output torque Te of the engine 10 and the actual speed ratio e from a predetermined relationship, and the line hydraulic pressure is adjusted to the transmission belt 24.
This is necessary and sufficiently controlled to the extent that slippage does not occur between the pulleys 18 and 18, and the variable pulleys 18, 22, and power loss is minimized as much as possible.

In the hydraulic control circuit configured as described above, hydraulic oil is discharged from the line oil passage 46 that supplies hydraulic oil to the speed ratio control valve 38, that is, the hydraulic oil supply passage to the hydraulic cylinder 26, and from the speed ratio control valve 38. A variable throttle valve device 70 is provided in the return oil path 50, that is, the hydraulic oil discharge path from the hydraulic cylinder 26.

That is, as shown in FIG. 2, the variable throttle valve device 70 communicates with a first flow passage 72 that communicates with the line oil passage 46 and constitutes a part of the hydraulic oil supply passage, and with the return oil passage 50. a valve housing 75 including a second flow passage 74 constituting a part of the hydraulic oil discharge passage; and a land portion 77;
In the valve housing 75, the first flow passage 7
2 and the second flow path 74, and in the neutral position, similar flow resistance is applied to the first flow path 72 and the second flow path 74; A spool 76 that increases the flow resistance on the moving direction side of the flow path 74 and lowers the flow resistance on the side opposite to the moving direction side.
and a weight 78 provided in the valve housing 75 at a position adjacent to the end of the spool 76 so as to be movable in the same moving direction as the spool 76, and when the moving direction of the weight 78 is horizontal, the spool 76 is moved. A pair of springs 80 and 82 are provided for positioning the spring in the neutral position. The variable throttle valve device 70 is attached to the vehicle so that the weight 78 is on the front side of the vehicle, and the moving direction of the weight 78 is in the front-rear direction of the vehicle, and is horizontal when the vehicle is on flat ground. It is being Note that the housing 75 allows the movement of the weight 78 housed in the storage chamber 86 and provides an appropriate braking effect to the movement, thereby making it less susceptible to sudden acceleration and deceleration of the vehicle on a flat road. A communication path 84 whose cross-sectional area is determined as follows is provided. Therefore, this communication path 84 constitutes a braking means for the weight 78. Further, the weight 78 and the springs 80, 82 that keep it in the neutral position on a flat road constitute a gradient sensing section.

The variable throttle valve device 70 may be configured as shown in FIG. That is, the annular groove 88 is formed in the spool 76, and the annular groove 88 is formed in the housing 75.
A stopper ring 90 is attached so as to be able to selectively come into contact with the inner side wall surface. The stopper ring 90 limits the stroke of the spool 76 within a necessary range.

Hereinafter, the effects of this embodiment will be explained with respect to the variable diaphragm device 70 shown in FIG. 3.

When the vehicle travels on a flat road, the weight 78 and the spool 76 are positioned at a position where the biasing forces of the springs 80 and 82 are parallel, so the spool 76, which functions as a throttle valve, is positioned at its neutral position and the above-mentioned Similar flow resistance is provided to the first flow path 72 and the second flow path 74. FIG. 3 shows this state.

When the vehicle travel path becomes positive, that is, when it becomes a climbing path,
The weight 78 mainly depends on the gravity acting on the weight 78.
is moved toward the rear of the vehicle toward the spring 80, so the first flow path 72 is narrowed and the second flow path 72 is narrowed.
The flow path 74 is further opened. FIG. 4 shows this state.

As a result, compared to a flat road, the flow resistance of the hydraulic oil supplied to the hydraulic cylinder 26 that exclusively changes the speed ratio increases, and the flow resistance of the hydraulic oil discharged from the hydraulic cylinder 26 is alleviated. , belt type continuously variable transmission 1
The rate of change in the increasing direction of the speed ratio of No. 4 is made smaller, and the rate of change in the decreasing direction is made larger. As a result, when the vehicle is traveling on a road with a curve, for example, the driver normally releases the accelerator pedal when the vehicle approaches the curve. At this time, since the flow resistance of the hydraulic oil to the hydraulic cylinder 26 is increased, the speed ratio is changed relatively slowly in the direction of increasing speed ratio at a lower change rate than when driving on a flat road. Since the speed ratio is not so large at the time of reading and moving on to pitching, relatively sufficient driving force is obtained, and the driver does not need to operate the accelerator pedal greatly. After that point, the flow resistance of the hydraulic oil flowing out from the hydraulic cylinder 26 is reduced, and the speed of change in the direction of reducing the speed ratio is higher than on a flat road, so the throttle opening is kept that large. There's no need. Therefore, when the vehicle is mounted, the range of change in the speed ratio does not become unnecessarily large, so there is no need to operate the accelerator pedal frequently, and suitable drivability and fuel consumption efficiency can be obtained.

On the other hand, when the vehicle travels on a negative road, that is, when it becomes a disembarking road, the weight 78 is moved toward the front of the vehicle toward the spring 82 in accordance with the gravity acting on the weight 78, so that it is less difficult to move than on a flat road. While the first flow path 74 is narrowed down, the second flow path 72 is further opened. FIG. 4 shows this state.

As a result, compared to a flat road, the flow resistance of the hydraulic oil discharged from the hydraulic cylinder 26 that adjusts the speed ratio increases, and the flow resistance of the hydraulic oil supplied to the hydraulic cylinder 26 is alleviated. The rate of change in the speed ratio of the belt-type continuously variable transmission 14 in the decreasing direction is reduced, and the rate of change in the increasing direction is increased. As a result, when exiting a curve on a descending road with a curve, the driver normally accelerates to compensate for the deceleration at the curve, but as mentioned above, the speed ratio change rate is low in the decreasing direction and high in the increasing direction ( This prevents the speed ratio from becoming too small than necessary when operating the accelerator after exiting a curve, and there is no need to return the accelerator pedal when the vehicle returns to steady driving.Therefore, when exiting the vehicle Even in this case, since the range of change in the speed ratio does not become unnecessarily large, there is no need to operate the accelerator pedal frequently, and suitable drivability and fuel consumption efficiency can be obtained.

In this way, according to the present embodiment, the speed ratio change speed of the belt type continuously variable transmission 1a14 is changed according to the running road gradient, so that the speed ratio changes on a running road with curves and uphill and downhill slopes. As a result, the range of change in the amount of fuel is reduced overall, the accelerator pedal operation is reduced, and the drivability and fuel consumption efficiency of the vehicle are suitably improved.

Further, according to this embodiment, since the communication passage 84 functions as a braking means, there is an advantage that movement of the weight 78 is suitably suppressed when the vehicle suddenly accelerates or decelerates.

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, the variable diaphragm device 70, as shown in FIG.
It may be provided in the oil passage between the speed ratio control valve 38 and the hydraulic cylinder 26.

Further, in the above embodiment, the variable throttle valve device 70 is provided in the hydraulic oil supply path and the hydraulic oil discharge path to the hydraulic cylinder 26, but it is not provided in one of the hydraulic oil supply path and the hydraulic oil discharge path. However, since the rate of change in one of the speed ratio change directions is set to an appropriate value according to the slope of the road, a certain effect can be obtained.

Further, in the above-described embodiment, one variable throttle valve device 70 that throttles the two flow passages, that is, the first flow passage 72 and the second flow passage 74, is provided in the hydraulic oil supply passage and the hydraulic oil discharge passage for the hydraulic cylinder 26. However, two variable throttle valve devices that throttle one flow path may be provided in the hydraulic oil supply path and the hydraulic oil discharge path to the hydraulic cylinder 26, respectively.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram illustrating the configuration of an embodiment of the present invention. FIG. 2 is a sectional view illustrating the configuration of the variable throttle valve device included in the hydraulic circuit diagram of FIG. 1. FIG. FIG. 3 is a diagram corresponding to FIG. 2 showing another example of the variable throttle valve device. 4 and 5 are views showing the operating state of the variable throttle valve device of FIG. 3. FIG. FIG. 6 is a diagram showing essential parts of another example of a hydraulic circuit according to the present invention. 10: Engine 14: Belt type continuously variable transmission (continuously variable transmission) 26: Hydraulic cylinder (hydraulic actuator) 70: Variable throttle valve device 76: Spool (throttle valve) Applicant Toyota Motor Corporation Figure 1 Figure 6

Claims (5)

[Claims] (1) In a continuously variable transmission for vehicles that continuously changes the speed of the engine and transmits it to the drive wheels, hydraulic oil is supplied to a hydraulic actuator that changes the speed ratio of the continuously variable transmission, or A hydraulic control device that adjusts the speed ratio by discharging hydraulic oil of the vehicle, the hydraulic control device being provided in at least one of a hydraulic oil supply path to the hydraulic actuator and a hydraulic oil discharge path from the hydraulic actuator, and A variable speed ratio changing speed of the continuously variable transmission is changed according to the running road gradient by changing the flow rate in at least one of the hydraulic oil supply path and the hydraulic oil discharge path in response to the running road gradient. A hydraulic control device for a continuously variable transmission for a vehicle, characterized by including a throttle valve device. (2) The variable throttle valve device is provided in at least one of a hydraulic oil supply path to the hydraulic actuator and a hydraulic oil discharge path from the hydraulic actuator. Claim 1, which comprises a throttle valve that changes the flow rate, and a gradient sensing section having a weight that drives the throttle valve by moving in response to the gradient of the road on which the vehicle travels. A hydraulic control device for a continuously variable transmission for a vehicle as described above. (3) The throttle valve is provided with a spool that is movable in the axial direction, and the weight of the gradient sensing section is movable in the longitudinal direction of the vehicle to respond to the inclination of the vehicle. The hydraulic control device for a continuously variable transmission for a vehicle according to claim 2, wherein the spool is driven by moving the spool. (4) The device for a vehicle according to claim 2 or 3, wherein the gradient sensing section is provided with a braking means for suppressing the weight from moving in accordance with sudden acceleration or deceleration of the vehicle. Hydraulic control device for gear transmission. (5) The continuously variable transmission is equipped with a pair of variable pulleys with variable effective diameters and a transmission belt wound between the variable pulleys, and the hydraulic actuator is the belt-type continuously variable transmission. The variable throttle valve device changes the effective diameter of the variable pulley on the input side of the machine, and the variable throttle valve device reduces the flow rate of the hydraulic oil supply path and discharges the hydraulic oil as the slope of the running road of the vehicle becomes positive. Conversely, as the slope of the running road becomes negative, the flow rate of the hydraulic oil supply path increases and the flow rate of the hydraulic oil discharge path decreases. A hydraulic control device for a continuously variable transmission for a vehicle according to any one of items 1 to 4.