JPH05256360A - Vehicular continuously variable transmission - Google Patents

Abstract

PURPOSE:To obtain a vehicular continuously variable transmission by which the power loss of a vehicle can be reduced as much as possible. CONSTITUTION:A boost pressure PB which is an action oil pressure in an oil passage on a lower pressure side among a first connection oil passage 40a and a second connection oil passage 40b is increased by a boost pressure control valve 138 following the increase of an operation amount of an acceleration pedal corresponding to the load of an engine or the load of a vehicle. Therefore, as the boost pressure PB is made to a necessary and sufficient pressure following the load of a vehicle, a power loss causing by the rotation drive of a boost pump is reduced as much as possible. At the same time, in a fluid transmission device 36 transmitting the power through an action oil between a first hydraulic pump motor 30 and a second hydraulic pump motor 38, the boost pressure PB is controlled following that load. Therefore, a transmission efficiency is raised up as much as possible and the power loss of the vehicle is also reduced in this point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuously variable transmission for a vehicle of a type in which a fluid transmission device for transmitting power through a working fluid between a pair of fluid pump motors is provided in a vehicle power transmission path. is there.

[0002]

2. Description of the Related Art A pair of fluid pump motors and a pair of connection conduits for connecting the pair of fluid pump motors to each other are provided, and a working fluid in the connection conduits is interposed between the pair of fluid pump motors. 2. Description of the Related Art There is known a continuously variable transmission for a vehicle of a type in which a fluid power transmission device for transmitting power is provided in a power transmission path of a vehicle. For example, Japanese Patent Publication No. 2-10302
That is the continuously variable transmission described in the publication.

[0003]

By the way, in the above-mentioned conventional continuously variable transmission for a vehicle, one of the pair of connecting pipes for connecting the pair of fluid pump motors to each other is connected to the drive side fluid pump motor. Since the fluid is supplied to the drive-side fluid pump motor, the pressure becomes relatively high, but the other connecting conduit is circulated from the driven-side fluid pump motor to the drive-side fluid pump motor. Therefore, the pressure becomes relatively low, and the pressure in the connection pipe on the low pressure side, that is, the boost pressure, is regulated so as to be an integral pressure higher than the maximum pressure required for power transmission. ..

However, the pressure in the low pressure side connecting pipe, that is, the boost pressure, is regulated on the basis of the working fluid pumped from the boost pump which is directly rotationally driven by the engine. If it is a constant set value as described above, it will be maintained unnecessarily high during normal driving, and the power loss of the vehicle will be too large to be ignored. Further, in the fluid transmission device that transmits power through the working fluid between the fluid pump motors, the boost pressure is set to a constant high value when the transmission torque is small, that is, when the load is small. Therefore, there is a drawback that the transmission efficiency is reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a continuously variable transmission for a vehicle in which power loss of the vehicle is reduced as much as possible. ..

[0006]

SUMMARY OF THE INVENTION The gist of the present invention for achieving the above object is to provide a pair of fluid pump motors and a pair of connecting conduits for connecting the pair of fluid pump motors to each other. A vehicle continuously variable transmission of the type having a fluid transmission device for transmitting power via a working fluid in the connection pipe between the pair of fluid pump motors, A boost pressure regulating device for regulating the pressure of the low-pressure side connecting line of the pair of connecting lines connecting the fluid pump motors to each other according to the load of the vehicle is included.

[0007]

With this configuration, the boost pressure regulator adjusts the pressure of the low-pressure side connecting line of the pair of connecting lines connecting the fluid pump motors to each other according to the load of the vehicle. It is regulated. For this reason, the boost pressure in the low-pressure side connection conduit is set to a necessary and sufficient pressure according to the load of the vehicle, so that the power loss due to the rotational drive of the boost pump is minimized. At the same time, even in a fluid transmission device that transmits power via a working fluid between fluid pump motors, boost pressure is adjusted according to the load, so that the transmission efficiency can be increased as much as possible. Also in, the power loss of the vehicle is reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a vehicle to which the present invention is applied, showing a continuously variable transmission 10 for a vehicle having a power transmission system called differential hydraulic transmission or power split hydraulic transmission. There is.

In the figure, the engine 12 is connected to a differential input pinion 16 of a differential gear unit 14 via an input shaft 18. The differential gear device 14 divides the torque input to the differential input pinion 16 and transmits the divided torque to the outer peripheral side gear 20 and the inner peripheral side gear 22 that mesh with it. The outer peripheral side gear 20 is connected to a high speed side clutch 26 via a first sleeve shaft 24. The gear 28 fixed to the first sleeve shaft 24 is meshed with the gear 32 fixed to the rotating shaft of the first hydraulic pump motor 30, and the first sleeve shaft 24 and the first hydraulic pump motor 30 are operative. Is linked to. The gear 32 is meshed with a gear 35 fixed to the rotary shaft of the boost pump 34, and the boost pump 34 is rotationally driven by the engine 12.

The fluid transmission 36 includes a second hydraulic pump motor 38 which is paired with the first hydraulic pump motor 30. One of the first hydraulic pump motor 30 and the second hydraulic pump motor 38 is driven. Then, a pair of the first connecting oil passage 40a and the second connecting oil passage 4 connecting them.
The power is transmitted via the hydraulic oil in 0b and the power is output from the other. The second hydraulic pump motor 38 is connected to a parallel shaft 42 that is parallel to the input shaft 18, and the parallel shaft 42 has a pair of gears 44 and 46.
And a low speed side clutch 50 via the second sleeve shaft 48. The first hydraulic pump motor 30 and the second
The hydraulic pump motors 38 are both variable displacement type, and their displacement volumes are changed by a first actuator 100 and a second actuator 102, which will be described later.

On the other hand, the inner peripheral side gear 22 of the differential gear unit 14 is connected to a forward clutch 54 via a gear 52 fitted to the parallel shaft 42 so as to be relatively rotatable. The forward clutch 54 connects the gear 52 to the parallel shaft 42 when moving forward. A center sleeve shaft 58 having a center gear 56 is relatively rotatably fitted between the first sleeve shaft 24 and the second sleeve shaft 48 of the input shaft 18. The high speed side clutch 26
Is for connecting the first sleeve shaft 24 to the center sleeve shaft 58 in the high speed mode, and the low speed side clutch 50 is for connecting the second sleeve shaft 48 to the center sleeve shaft 58 in the low speed mode.

The power output from the center gear 56 is transmitted to a drive wheel 70 via a reduction shaft (output shaft) 64 having a pair of gears 60 and 62, a final reduction gear 66, and a pair of axles 68. It is like this. When the forward clutch 54 is located at the forward position, the gear 5
There is provided a one-way clutch 72 that does not restrain the rotation of the gear 2 and prevents rotation of the gear 52 in one direction when the gear 52 is positioned at the reverse position.

As shown in FIG. 2, the electronic control unit 74 is
A microcomputer provided with a CPU 76, a ROM 78, a RAM 80, an input interface 82, an output interface 84, etc., and the CPU 76 is a RAM 8
The input signal is processed in accordance with a program stored in advance in the ROM 78 while using the temporary storage function of 0, and the speed ratio e (= output is set so that the engine 12 operates along an optimum curve that provides fuel economy and drivability, for example. Shaft rotation speed N
_out / input shaft rotation speed N _in ) is adjusted. That is, in the electronic control unit 74, the input shaft rotation sensor 90 that detects the rotation speed N _in of the input shaft 18 and the rotation speed N of the output shaft 64.
an output shaft rotation sensor 92 for detecting the _out, a throttle sensor 94 for detecting a throttle valve opening theta _th, first hydraulic pressure sensor 96 for detecting the hydraulic pressure in the first connecting oil passage 40a, the hydraulic pressure in the second connecting oil channel 40b The input signal from the second hydraulic sensor 98 for detecting the speed is sequentially read, the speed ratio e is calculated based on the output shaft rotation speed N _out and the input shaft rotation speed N _in , and the vehicle speed V is the output shaft rotation speed N. Calculated based on _out .

In the gear ratio feedback control of the electronic control unit 74, the target input shaft rotation speed N _In ° or the target speed ratio e ° is determined based on the actual throttle valve opening θ _th and the vehicle speed V from the relationship stored in advance. The first input speed is determined so that the actual input shaft rotation speed N _In or the speed ratio e matches.
Hydraulic pump motor 30 and second hydraulic pump motor 38
Is changed by the first actuator 100 and the second actuator 102 to adjust the speed ratio e. Further, when the vehicle is running at a low speed that requires a driving force such as when starting, the low speed mode is selected, the forward clutch actuator 104 engages the forward clutch 54, and the low speed clutch actuator 106 engages the low speed side clutch 50. Be done. In this case, the first hydraulic pump motor 30 to the second hydraulic pump motor 38
Power is transmitted to. On the contrary, during high speed traveling, the high speed mode is selected, the forward clutch actuator 104 engages the forward clutch 54, and the high speed clutch actuator 108 engages the high speed side clutch 26. In this case, power is transmitted from the second hydraulic pump motor 38 to the first hydraulic pump motor 30. When the change in the gear ratio feedback control falls within a predetermined range, the high speed side clutch 26 and the low speed side clutch 50 are both engaged, and the hydraulic pressure in the first connecting oil passage 40a and the second connecting oil passage 40b are engaged. The first actuator 100 so that the pressure difference from the internal oil pressure becomes zero.
And the second actuator 102 is operated.

FIG. 3 is a hydraulic control circuit 110 for supplying hydraulic fluid to the fluid transmission 36 of FIG. 1 and its first connecting oil passage 40a and second connecting oil passage 40b and adjusting the boost pressure P _B. And in detail. In the fluid transmission device 36, a predetermined distance in the first connection oil passage 40a is provided between the pair of first connection oil passage 40a and second connection oil passage 40b that connect the first hydraulic pump motor 30 and the second hydraulic pump motor 38. A first relief valve 111 for preventing over-pressurization above a certain value, a second relief valve 112 for preventing over-pressurization over a predetermined value in the second connecting oil passage 40b, and a pair of boost check valves 114a at both ends. And 114b
And a low pressure side supply oil passage 118, a first connection oil passage 40a and a second connection oil passage 118 which are connected to a boost line oil passage 116 described later.
Refresh valves 124 each having a valve element 122 that is driven by the differential pressure of the connecting oil passage 40b to connect the oil passage on the low pressure side to the output port 120 are provided.

In the hydraulic control circuit 110, the hydraulic oil that has flowed back into the oil tank 130 is the boost pump 3
4 through the filter 132 through the boost line oil passage 1
It is designed to be pumped to 16. A line relief valve 134 is provided in the boost line oil passage 116 to prevent boosting above a predetermined set value. The hydraulic oil in the boost line oil passage 116 is the same as the first actuator 100, the second actuator 102,
Forward clutch actuator 104, low speed clutch actuator 106, high speed clutch actuator 108
Is supplied via a control valve (not shown) provided correspondingly to drive the first connecting oil passage 40a through the low pressure side oil supply passage 118 and one of the pair of boost check valves 114a and 114b. And the second
It is supplied to the low pressure side oil passage of the connection oil passage 40b.

The first connecting oil passage 40a and the second connecting oil passage 4
The hydraulic oil in the low pressure side oil passage of 0b is made to flow from the output port 120 of the refresh valve 124 to the discharge passage 136, and further made to flow into the oil tank 130 via the boost pressure regulating valve 138 and the oil cooler 140. It is designed to be used. Further, although the pressure increasing port 142 of the boost pressure regulating valve 138 is communicated with the drain oil passage 144,
When in the pressure boosting mode, the boost pressure P, which is the hydraulic pressure in the discharge passage 136, that is, the working hydraulic pressure in the oil passage on the low pressure side of the first connection oil passage 40a and the second connection oil passage 40b, is applied to the pressure increase port 142. _B is actuated and its boost pressure P _B
An electromagnetic switching valve 146 is provided for increasing the temperature. In the pressure increasing mode, the actuators 100, 102,
The electronic control unit 74 automatically selects the actuators 104, 106, 108 and the like when actuated to improve the responsiveness of those actuators and the responsiveness of the continuously variable transmission.

The boost pressure regulating valve 138 is provided movably in the valve chamber to open and close between the discharge passage 136 and the oil cooler 140, and the valve 150 is urged in the valve closing direction. Spring 152
And the valve element 150, the spring 152 is sandwiched between the valve element 150 and the valve element 150. The spring 152 is moved by receiving the boost pressure P _B supplied to the pressure boosting port 142 to move the urging force of the spring 152. Plunger 1 to increase
54 and a cam follower 158 provided on the plunger 154 so as to engage with the throttle cam 156. Therefore, the boost pressure P _B and the hydraulic pressure in the boost line oil passage 116 are controlled to the pressure corresponding to the biasing force of the spring 152 with respect to the valve element 150, so that the pressure increasing mode is selected and the plunger 154 boosts. A predetermined pressure is raised by receiving and moving the pressure P _B , while it is raised with the rotation of the throttle cam 156 which rotates with the operation of an accelerator pedal not shown.

As described above, according to the present embodiment, as shown in FIG. 4, the boost pressure regulating valve 138 controls the increase of the operation amount of the accelerator pedal corresponding to the load of the engine 12 or the load of the vehicle. The boost pressure P _B that is the operating oil pressure in the low pressure side oil passage of the first connecting oil passage 40a and the second connecting oil passage 40b is increased. Therefore, the boost pressure P _B is set to a necessary and sufficient pressure according to the load of the vehicle, and the power loss due to the rotational drive of the boost pump 34 is minimized. At the same time, the boost pressure P _B is adjusted in accordance with the load in the fluid transmission device 36 that transmits power via hydraulic oil between the first hydraulic pump motor 30 and the second hydraulic pump motor 38. The transmission efficiency can be increased as much as possible, and the power loss of the vehicle is reduced in this respect as well. Therefore, when traveling with low output torque is common, such as in passenger vehicles,
The effect of reducing the power loss of the continuously variable transmission 10 and improving the efficiency is remarkably obtained, and the fuel efficiency is improved.

Next, another embodiment of the present invention will be described. In the following description, the same parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the embodiment shown in FIG. 5, a pair of first
A switching valve 164 provided with a spherical valve element 162 that connects the high pressure side oil passage of the oil passages 40a and 40b to the output port 160 is provided between the connection oil passage 40a and the second connection oil passage 40b. ing. Boost pressure regulator valve 138
Is provided with a biasing device 166 that biases the plunger 154 with thrust having a magnitude corresponding to the hydraulic pressure output from the output port 160 of the switching valve 164. The urging device 166 includes a piston 168 arranged to be movable in the axial direction so as to come into contact with the plunger 154, and a spring 170 for urging the piston 168 in the backward direction, that is, downward in FIG. And the first connecting oil passage 40
The piston 168 is driven according to the oil pressure P _H in the high-pressure side oil passage of the a and the second connection oil passage 40b.

First connecting oil passage 40a and second connecting oil passage 4
Since the hydraulic pressure P _H in the high-pressure side oil passage of 0b has a magnitude corresponding to the transmission power of the fluid transmission device 36, it shows a value corresponding to the load of the engine 12 or the load of the vehicle. Therefore, also in the present embodiment, as shown in FIG. 6, the boost pressure P _B is set to a necessary and sufficient pressure according to the load of the vehicle, so that the power loss due to the rotational drive of the boost pump 34 is possible. Be made smaller. Also, the first
Hydraulic pump motor 30 and second hydraulic pump motor 38
Even in the fluid transmission device 36 that transmits power through the hydraulic oil between the two, the boost pressure P _B is regulated according to the load, so that the transmission efficiency thereof can be increased as much as possible. Power loss of the vehicle is reduced.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention can be applied to other modes.

For example, the urging device 166 of the boost pressure regulating valve 138 shown in FIG. 5 has the oil pressure P _B in the oil passage on the high pressure side of the first connecting oil passage 40a and the second connecting oil passage 40b.
However, the thrust force is generated based on a signal pressure having a magnitude corresponding to the throttle valve opening θ _th , the negative pressure of the intake pipe of the engine 12, the intake air amount of the engine 12, and the like. May be configured to generate. The magnitude signal pressure corresponding to the throttle valve opening θ _th , the negative pressure of the intake pipe of the engine 12, and the intake air amount of the engine 12 can be generated by a mechanically configured valve. It can also be generated by a linear valve which operates according to a signal.

Further, in the above-described embodiment, the boost pressure adjusting valve 138 is provided between the refresh valve 124 and the oil cooler 140, but it may be inserted in the boost line oil passage 116. Further, the boost pressure regulating valve 138 may be a relief valve type regulating valve.

In the above-described embodiment, both the first hydraulic pump motor 30 and the second hydraulic pump motor 38 are variable displacement type motors, but one of them may be a low displacement type pump motor.

Further, the continuously variable transmission 10 of the above-mentioned embodiment.
Is configured to transmit power in an input distribution form, but may be configured to transmit power in an output distribution form. Further, it is also possible to configure a pure hydraulic continuously variable transmission using only a pump motor.

The above description is merely one embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration of a continuously variable transmission for a vehicle and a hydraulic system thereof to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating a configuration of a control device included in the embodiment of FIG.

FIG. 3 is a diagram illustrating in detail the configuration of the hydraulic circuit of FIG.

FIG. 4 is a diagram showing a pressure adjusting characteristic of boost pressure P _B by the boost pressure adjusting valve of the embodiment shown in FIG.

FIG. 5 is a view corresponding to FIG. 3 in another embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 4 in another embodiment of the present invention.

[Explanation of symbols]

 10 continuously variable transmission 30 first hydraulic pump motor (fluid pump motor) 36 fluid transmission device 38 second hydraulic pump motor (fluid pump motor) 40a, 40b connection oil passage (connection pipe line) 138 boost pressure regulating valve (boost pressure) Pressure regulator)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Nakakoji 1 Nishinokyo Kuwaharacho, Nakagyo-ku, Kyoto City Shimadzu Corporation

Claims (1)

[Claims] 1. A pair of fluid pump motors, and a pair of connection conduits for connecting the pair of fluid pump motors to each other, wherein a working fluid in the connection conduits is provided between the pair of fluid pump motors. A continuously variable transmission for a vehicle of a type having a fluid transmission device for transmitting power via a power transmission path of a vehicle, wherein a low pressure side connection of a pair of connection pipelines interconnecting the fluid pump motors is provided. A continuously variable transmission for a vehicle, comprising: a boost pressure regulator that regulates the pressure in the pipeline according to the load on the vehicle.