JPH07117147B2 - Hydraulic control device for continuously variable transmission for vehicles - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic control device for a continuously variable transmission for a vehicle, and more particularly to a technique for improving drivability on an uphill road or a downhill road with many curves.

2. Description of the Related Art A continuously variable transmission for a vehicle that continuously changes the rotation of an engine and transmits it to driving wheels is known. A vehicle equipped with such a continuously variable transmission has a high fuel consumption rate of the engine when traveling. Since the operating conditions can be selected, higher fuel consumption efficiency can be obtained compared to the conventional vehicle equipped with a stepped transmission, and moreover,
Since the speed ratio (output shaft rotation speed / input shaft rotation speed) can be changed steplessly, there is an advantage that shift shock does not occur. Conventionally, many control devices for controlling the speed ratio of such a continuously variable transmission for vehicles have been proposed, and the basic one is, for example, an accelerator operation amount, etc. The target rotation speed or target speed ratio is determined from the relationship obtained in advance to obtain the optimum fuel consumption rate based on the indicated amount, and the target rotation speed or target speed ratio and the actual input shaft rotation speed or speed of the continuously variable transmission are determined. The control is performed so that the ratio matches. In such a continuously variable transmission control device, generally, in consideration of the fuel consumption rate and drivability centering on a flat road, a predetermined change speed is set so that the actual input shaft rotation speed or speed ratio matches the target value. Can be changed at.

In such a conventional control device, the setting of the change speed of the continuously variable transmission is also set centering on a flat road, so that the acceleration responsiveness of the vehicle is poor on a traveling road with many curves and slopes such as mountain roads. In some cases, sufficient drivability could not be obtained.

On the other hand, a technique for applying engine braking when the vehicle is traveling downhill (Japanese Patent Laid-Open No. 58-191359) and a technique for correcting the target speed ratio to be small when the vehicle is climbing (Japanese Patent Laid-Open No. 58-1808).
No. 64) is proposed.

Problems to be Solved by the Invention However, even with such a conventional technique, when the vehicle is traveling on a road with many curves such as a mountain road and many uphills and downhills, the acceleration / deceleration operation must be frequently repeated. Then, the speed ratio changing speed at which the speed ratio is changed becomes a problem rather than the correction of the target speed ratio. That is, in the case of traveling on an uphill road accompanied by a curve, the accelerator pedal is normally returned by the driver when the vehicle approaches the curve. In this case, the speed ratio can be changed relatively fast in the direction with a large speed ratio at the speed of change set on the premise of a flat road, but at the time when the vehicle subsequently moves uphill, the speed ratio is considerably large. Due to insufficient driving force, the driver has to operate the accelerator pedal greatly. Further, after the above time point, the changing speed in the direction of decreasing the speed ratio is too slow at the value set on the premise of the flat road, so that the throttle opening must be kept large. On the other hand, when going through a curve on a downhill road accompanied by a curve, the normal driver performs an acceleration operation to compensate for deceleration on the curve. At this time, for the same reason as in the case described above, the speed ratio becomes unnecessarily small and the accelerator pedal must be released at the time of starting steady running. Therefore, in the conventional control device, since the change width of the speed ratio becomes unnecessarily large, it is necessary to frequently perform the accelerator pedal operation on a traveling road with many curves such as a mountain road and many uphills and downhills. The drivability deteriorated, and sufficient fuel consumption efficiency was not obtained.

Means for Solving the Problems The present invention has been made in view of the above circumstances, and the gist of the present invention is to provide a vehicle-less drive that continuously changes the rotation of the engine and transmits the rotation to the drive wheels. In a continuously variable transmission, a hydraulic control device for adjusting a speed ratio by supplying hydraulic oil to a hydraulic actuator for changing a speed ratio of the continuously variable transmission or discharging the hydraulic oil in the hydraulic actuator, Provided on at least one of a hydraulic oil supply passage for the hydraulic actuator and a hydraulic oil discharge passage from the hydraulic actuator, and in response to a traveling road gradient, the hydraulic oil supply passage is flat on an uphill road of the vehicle. The flow cross-sectional area is smaller than that of the road, and the flow cross-sectional area is larger than that of the flat road if it is a downhill road. A variable throttle that changes the speed ratio change speed of the continuously variable transmission according to the slope of the traveling road by increasing the flow cross-sectional area as compared with the road and decreasing the flow cross-sectional area as compared with the flat road if the road is a downhill road. It is to include a valve device.

With this configuration, the variable throttle valve device responds to the gradient of the traveling path of the vehicle, and in the hydraulic oil supply path, if the vehicle is an uphill road, has a distribution cross-sectional area larger than that of a flat road. In the case of a downhill road, the distribution cross-sectional area is made larger than that of a flat road if the road is downsized, and in the hydraulic oil discharge path, the distribution cross-sectional area is made larger than that of a flat road if it is an uphill road and a flat road if it is a downhill road. By reducing the flow cross-sectional area in comparison with, the flow rate of the hydraulic oil supply passage and the hydraulic oil discharge passage is changed according to the running road gradient, and the speed ratio change speed of the continuously variable transmission is set to the running road gradient. Therefore, the speed ratio of the continuously variable transmission is changed at an optimum changing speed according to the traveling road gradient on a traveling road having a curve and having an upslope and a downslope. Therefore, the change width of the speed ratio is reduced as a whole, the operation of the accelerator pedal is reduced, and the drivability of the vehicle and the fuel consumption efficiency are suitably improved.

The variable throttle valve device is preferably provided in at least one of a hydraulic oil supply passage for the hydraulic actuator and a hydraulic oil discharge passage from the hydraulic actuator to provide at least one of the hydraulic oil supply passage and the hydraulic oil discharge passage. And a gradient sensing unit having a weight that drives the throttle valve by moving in response to the road gradient of the vehicle.

Further, preferably, the throttle valve is provided with a spool that is movably provided in an axial direction, and a weight of the gradient sensing unit is movably provided in a front-rear direction of the vehicle. It is configured to drive the spool by moving according to the inclination.

Further, the gradient sensing unit is preferably configured to include a control unit that restrains the weight of the gradient sensing unit from moving in accordance with a sudden acceleration / deceleration of the vehicle.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, the engine 10 has a magnetic powder type electromagnetic clutch,
A belt type continuously variable transmission 14 is connected via a clutch 12 such as a centrifugal clutch, and after the rotation of the engine 10 is steplessly changed by the belt type continuously variable transmission 14, a differential reduction gear (not shown), etc. Is transmitted to the drive wheel via the. The belt type continuously variable transmission 14 is attached to the input shaft 16 connected to the clutch 12, the variable pulley 18 having a variable effective diameter attached to the input shaft 16, the output shaft 20, and the output shaft 20. The variable pulley 22 having a variable effective diameter, the transmission belt 24 stretched between the variable pulleys 18 and 22, and the variable pulley 18
And hydraulic cylinders 26 and 28 for changing the effective groove diameter by changing the V groove width. Variable pulley 18 and
Fixed rotating bodies 30 and 32 fixed to the input shaft 16 and the output shaft 20, respectively, and fixed rotating bodies 30 and 32 fixed to the input shaft 16 and the output shaft 20 so as to be movable in the axial direction and non-rotatable around the shaft, respectively. And 32, and movable rotary bodies 34 and 36 that form V-grooves between them, respectively. The movable rotary bodies 34 and 36 are driven in the axial direction by the hydraulic pressure applied to the spaces in the hydraulic cylinders 26 and 28. By doing so, the hanging diameter (effective diameter) of the transmission belt 24 can be continuously changed. The line 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 the speed ratio control valve 38 so that the movable rotary members 34 and 36 are acted on. The force balance is changed so that the speed ratio of the input shaft 16 and the output shaft 20 of the continuously variable transmission can be changed.

The line oil pressure is obtained by adjusting the pressure of the hydraulic oil pumped from the oil tank 40 by the pump 42 by the line oil pressure adjusting 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 described later and a valve element driven by the linear solenoid, and releases the hydraulic oil pressure-fed from the pump 42 to the oil tank 40. Is adjusted according to the pressure regulation signal SP to regulate the line hydraulic pressure. 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 linear solenoids driven by speed ratio signals SS1 and SS2 to be described later, respectively. And a valve element driven by a linear solenoid. The inflow-side flow control servo valve 38A adjusts the amount of hydraulic oil to the hydraulic cylinder 26 by connecting the oil passage 48 communicating with the hydraulic cylinder 26 and the line oil passage 46 to change the flow area. On the other hand, the outflow side flow rate control servo valve 38B connects the oil passage 48 and the return oil passage 50 to the oil tank 40 to change the flow area thereof, thereby adjusting the amount of hydraulic oil discharged in the hydraulic cylinder 26. That is, communication between the oil passage 48 and the line oil passage 46 and the oil passage 50 is blocked by the inflow side flow rate control servo valve 38A and the outflow side flow rate control servo valve 38B, and the amount of hydraulic oil in the hydraulic cylinder 26 is made constant. In this state, the speed ratio is fixed, while in the state where the oil passage 48 and the line oil passage 46 are communicated by the inflow side flow control servo valve 38A, the amount of hydraulic oil in the hydraulic cylinder 26 is increased. Thus, the effective diameter of the variable pulley 18 is increased and the effective diameter of the variable pulley 22 is decreased, and the speed ratio is increased at a changing speed according to the magnitude of the speed ratio signal SS1. On the contrary, when the oil passage 48 and the return oil passage 50 are communicated with each other by the outflow side flow rate control servo valve 38B, the speed ratio is reduced at a changing speed according to the magnitude of the speed ratio signal SS2.

The accelerator pedal is installed in the intake pipe of the engine 10.
A throttle valve 54 that is opened / closed in conjunction with the operation of 52 is attached, and a throttle sensor 56 attached to the throttle valve 54 opens an opening θ of the throttle valve 54.
_A throttle signal TH, which is a voltage corresponding to TH, is supplied to the microcomputer 58. Further, the vehicle is provided with an inclinometer 60 for detecting the traveling road surface gradient, and the inclination signal SK representing the traveling road surface gradient θ is supplied to the microcomputer 58.
Is supplied to. And, the input shaft 16 and the output shaft 20,
A rotation sensor 62 for detecting their rotation speed and
64 are provided respectively, and the rotation sensors 62 and 64 respectively supply pulsed rotation signals SI and SO corresponding to the rotation of the input shaft 16 and the output shaft 20 to the microcomputer 58.

The microcomputer 58 includes a CPU, a RAM, a ROM, an A / D converter, an interface, and the like, and the CPU processes an input signal supplied while utilizing the storage function of the RAM according to a program stored in advance in the ROM, and an actual The speed ratio signals SS1 and SS2 for matching the speed ratio with the target speed ratio are output to the flow rate control servo valves 38A and 38B, and the pressure adjusting signal SP indicating the line hydraulic pressure is output to the line hydraulic pressure regulating valve 44.
Output to. The speed ratio signals SS1 and SS2 are voltage signals representing the speed ratio changing direction and the speed ratio changing speed, respectively, and the actual speed ratio was determined from the relationship obtained in advance so that the fuel efficiency and drivability were optimized. It is set to "0" when it 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 the relationship obtained in advance, and the line hydraulic pressure is determined by the transmission belt 24 and the variable pulley. Between 18 and 22, it is necessary and fully controlled within the range where slippage does not occur, and power loss is made as small as possible.

In the hydraulic control circuit configured as described above, 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 the speed ratio control valve 38.
A variable throttle valve device 70 is provided in a return oil passage 50 for discharging hydraulic oil from the hydraulic cylinder 26, that is, a hydraulic oil discharge path from the hydraulic cylinder 26.

That is, as shown in FIG. 2, the variable throttle valve device 70 is
A first flow passage 72 communicating with the line oil passage 46 and forming a part of the hydraulic oil supply passage, and a second flow passage 74 communicating with the return oil passage 50 and forming a part of the hydraulic oil discharge passage. Has a valve housing 75 and a land portion 77, and the first flow passage 72 and the second flow passage are provided in the valve housing 75.
The first flow passage 72 and the second flow passage 74 are provided so as to be movable in the direction orthogonal to 74, and give the same flow resistance to the first flow passage 72 and the second flow passage 74 at the neutral position. Adjacent to the spool 76, which increases the flow resistance by decreasing the flow cross-sectional area on the moving direction side and reduces the flow resistance by increasing the flow cross-sectional area on the opposite side, and the end of the spool 76 in the valve housing 75. The weight is movably installed in the same position as the spool 76 at the
When the moving direction of 78 and the weight 78 is horizontal, the spool
A pair of springs 80 and 82 for positioning the 76 at the neutral position are provided. Then, the variable throttle valve device 70 has a weight 78.
Is on the front side of the vehicle, and the weight 78 is attached to the vehicle so that the moving direction is horizontal when the vehicle is in the front-rear direction of the vehicle and the vehicle is on a flat ground. It should be noted that the housing 75 allows movement of the weight 78 accommodated in the accommodation chamber 86 and imparts an appropriate braking action to the movement so that it is less susceptible to sudden acceleration / deceleration of the vehicle on a flat road. Is provided with a communication passage 84 whose cross-sectional area is determined. Therefore, the communication passage 84 constitutes a braking means for the weight 78. Further, the weight 78 and the springs 80 and 82 for holding the weight 78 in the neutral position on the flat road constitute a gradient sensing unit.

The variable throttle valve device 70 may be configured as shown in FIG. That is, an annular groove 88 is formed in the spool 76, and a stopper ring 90 is attached to the housing 75 so as to be capable of selectively contacting the side wall surface in the annular groove 88. The stopper ring 90 limits the stroke of the spool 76 within the required range.

Hereinafter, the function and effect of this embodiment will be described with reference to FIG.
70 will be described.

When the vehicle's driveway is flat, the spring 80 and
Since the weight 78 and the spool 76 are positioned at a position where the biasing force of 82 is parallel, the spool 76 that functions as a throttle valve
Is positioned at its neutral position and imparts similar flow resistance to the first flow passage 72 and the second flow passage 74. FIG. 3 shows this state.

When the traveling path of the vehicle becomes positive, that is, when it becomes an uphill road,
Since the weight 78 is moved toward the spring 80 toward the rear of the vehicle mainly according to the gravity acting on the weight 78, the first flow passage 72 is narrowed and the second flow passage 74 is
Will be opened more. FIG. 4 shows this state. As a result, compared with the 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 mitigated. The changing speed in the increasing direction of the speed ratio of the belt type continuously variable transmission 14 is decreased and the changing speed thereof in the decreasing direction is increased. As a result, for example, when traveling on an uphill road accompanied by a curve, the accelerator pedal is normally returned by the driver 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 relatively slowly changed in the speed ratio increasing direction at a changing speed lower than that on the flat road. Then, when the vehicle moves uphill, the speed ratio is not so large, so that the driving force is relatively sufficient and the driver does not need to operate the accelerator pedal greatly. After that point, the flow resistance in the direction in which the hydraulic oil discharged from the hydraulic cylinder 26 is reduced and the speed ratio is decreased is higher than that on a flat road, so the throttle opening is kept so large. No need. Therefore, when the vehicle is climbing uphill,
Since the change width of the speed ratio does not unnecessarily increase, it is not necessary to frequently operate the accelerator pedal, and suitable drivability and fuel consumption efficiency can be obtained.

On the other hand, when the traveling path of the vehicle becomes negative, that is, when the vehicle descends on a downhill, the weight 78 is moved toward the spring 82 side toward the front of the vehicle according to the gravity acting on the weight 78. The second flow passage 74 is narrowed down and the first flow passage 72 is further opened. FIG. 4 shows this state. As a result, compared with a flat road, the flow resistance of the hydraulic oil discharged from the hydraulic cylinder 26 for adjusting the speed ratio is increased, and the flow resistance of the hydraulic oil supplied to the hydraulic cylinder 26 is relaxed, The changing speed of the speed ratio of the belt type continuously variable transmission 14 in the decreasing direction is reduced and the changing speed thereof in the increasing direction is increased. As a result, for example, when exiting a curve on a downhill road accompanied by a curve, the driver usually performs an acceleration operation to compensate for deceleration on the curve, but as described above, the speed ratio changing speed is set to be low in the decreasing direction and high in the increasing direction. Therefore, the speed ratio does not become unnecessarily small when the accelerator is operated after passing through the curve, and it is not necessary to return the accelerator pedal at the time of shifting to steady running. Therefore, the variation range of the speed ratio does not unnecessarily increase even when the vehicle is descending a slope, so that it is not necessary to frequently operate the accelerator pedal, and suitable drivability and fuel consumption efficiency can be obtained. .

As described above, according to this embodiment, the variable throttle valve device 70 includes the first flow passage 72 that constitutes a part of the hydraulic oil supply passage for the hydraulic cylinder 26, and a portion of the hydraulic oil discharge passage from the hydraulic cylinder 26. Is provided in at least one of the second flow passages 74, and in the first flow passage 72, the amount of circulation of the first flow passage 72 is smaller in the first flow passage 72 in the case of an uphill road than in a flat road in response to the slope of the traveling road. If it is a downhill road, it is the first compared to a flat road
The flow volume of the flow passage 72 is increased, and in the second flow passage 74,
If it is an uphill road, the circulation amount of the second flow passage 74 is larger than that of a flat road, and if it is a downhill road, the second flow passage 74 is larger than that of a flat road.
The belt type continuously variable transmission 14 is modified by reducing the flow amount of 74 and changing the flow amount of at least one of the first flow passage 72 and the second flow passage 74 in response to the traveling road gradient of the vehicle.
Because the speed ratio change speed of is changed, on a road with a curve and also with an upslope and a downslope,
The change range of the speed ratio is reduced as a whole, the operation of the accelerator pedal is reduced, and the drivability of the vehicle and the fuel consumption efficiency are suitably improved.

Further, according to the present embodiment, since the communication passage 84 functions as a braking means, there is an advantage that the movement of the weight 78 during the sudden acceleration / deceleration of the vehicle is suitably suppressed.

The embodiment of the present invention has been described above with reference to the drawings.
The present invention also applies to other aspects.

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

Further, in the above-described embodiment, the variable throttle valve device 70 is provided in the hydraulic oil supply passage and the hydraulic oil discharge passage for the hydraulic cylinder 26, but is provided in one of the hydraulic oil supply passage and the hydraulic oil discharge passage. However, since one of the changing speeds in the speed ratio changing direction is set to an appropriate value according to the traveling road gradient, a temporary 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 passage may be provided in the hydraulic oil supply passage and the hydraulic oil discharge passage for the hydraulic cylinder 26, respectively.

The above description is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram for explaining the configuration of an embodiment of the present invention. FIG. 2 is a sectional view for explaining the configuration of the variable throttle valve device included in the hydraulic circuit diagram of FIG. FIG. 3 is a view corresponding to FIG. 2 showing another example of the variable throttle valve device.
4 and 5 are diagrams showing the operating state of the variable throttle valve device of FIG. FIG. 6 is a diagram showing a main part of another hydraulic circuit example of the present invention. 10 ... Engine 14 ... Belt type continuously variable transmission (continuously variable transmission) 26 ... Hydraulic cylinder (hydraulic actuator) 70 ... Variable throttle valve device 72 ... First flow passage (hydraulic oil supply passage) 74 ... Second flow passage ( Hydraulic fluid discharge path) 76 ... Spool (throttle valve) 78 ... Weight (gradient sensing section) 80,82 ... Spring (gradient sensing section) 84 ... Communication path (control means)

Claims (4)

[Claims] 1. A continuously variable transmission for a vehicle, which continuously changes the rotation of an engine and transmits it to driving wheels, by supplying hydraulic oil to a hydraulic actuator for changing a speed ratio of the continuously variable transmission or by supplying the hydraulic pressure to the hydraulic actuator. A hydraulic control device for adjusting the speed ratio by discharging hydraulic oil from an actuator, wherein the hydraulic control device is provided in at least one of a hydraulic oil supply path for the hydraulic actuator and a hydraulic oil discharge path from the hydraulic actuator, and runs. In response to a road gradient, in the hydraulic oil supply path, if the vehicle is an uphill road, the distribution cross-sectional area is smaller than that of a flat road, and if it is a downhill road, the distribution cross-sectional area is larger than that of a flat road, In the hydraulic oil discharge passage, if the road is an uphill road, the flow cross-sectional area is larger than that of a flat road, and if the road is a downhill road, the flow cross-sectional area is smaller than that of a flat road. According to the aspect of the invention, there is provided a hydraulic control device for a continuously variable transmission for a vehicle, which includes a variable throttle valve device that changes a speed ratio change speed of the continuously variable transmission according to the traveling road gradient. 2. The variable throttle valve device is provided in at least one of a hydraulic oil supply passage for the hydraulic actuator and a hydraulic oil discharge passage from the hydraulic actuator, and at least one of the hydraulic oil supply passage and the hydraulic oil discharge passage. A throttle valve that changes the flow cross-sectional area on one side, and a gradient sensor having a weight that drives the throttle valve by moving in response to the traveling road gradient of the vehicle. 2. A hydraulic control device for a continuously variable transmission for a vehicle according to item 1. 3. The throttle valve is provided with a spool movably provided in an axial direction, and a weight of the gradient sensing portion is movably provided in a front-rear direction of the vehicle so that the vehicle tilts. The hydraulic control device for a vehicle continuously variable transmission according to claim 2, wherein the spool is driven by moving in accordance with the above. 4. The vehicle according to claim 2 or 3, wherein the gradient sensing unit includes a braking unit that restrains the weight of the gradient sensing unit from moving according to sudden acceleration and deceleration of the vehicle. Hydraulic control system for continuously variable transmissions.