JPH01178037A - Driving system equipped with continuously variable transmission - Google Patents

Abstract

PURPOSE:To eliminate the unnecessary accelerator operation and improve the efficiency of the system by setting the differential pressure between the circuits of the fluid type transmission systems to zero by compulsorily generating an intermediate lock-up mode in a switching region between the high and low speed modes. CONSTITUTION:The output of an engine I is transmitted to a traveling wheel IV through a continuously variable transmission II and a final reduction gear III. The continuously variable transmission II is equipped with a differential gear mechanism 4. plural fluid pump/motors 7 and 8, fluid transmission mechanism 12, low and high speed side clutches 14 and 15, etc. In this case, each pushing-out capacity of the fluid pump/motors 7 and 8 is controlled by each actuator 44, 45 so that the differential pressure between the circuits in the fluid type transmission systems A and B becomes zero in the intermediate lock-up mode where the both clutches 14 and 15 are connected. In the middle part of an accelerating wire 58, a control means 60 which corrects the shift to be transmitted in the intermediate lock-up mode and converges the engine I to an aimed revolution speed is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a drive system with a continuously variable transmission device that can be widely used in various industrial fields such as industrial machinery and vehicles.

[Prior Art] A so-called hydraulic transmission (HST) is known as a continuously variable transmission using a fluid pump/motor. However, although this one has excellent continuously variable speed,
The efficiency is not always good and the speed range is not satisfactory. Therefore, by using the H8T and a differential gear mechanism together and sharing power transmission between the H3T and the differential gear mechanism, both the continuously variable speed of the H3T and the high efficiency of gear transmission can be achieved. A hydromechanical continuously variable transmission (HMT) has been developed that allows
Hydraulic Engineering (edited by Tomoo Ishihara, Asakura Shobo), Theory and Practice of Piston Pump Motors (edited by Sadao Ishihara, Corona Publishing)). That is,
This continuously variable transmission has a first, second, and third input/output end, and a low-speed mechanical transmission system that passes between the first input/output end and the second input/output end; The first input/output terminal and the third
A differential gear mechanism that forms a high-speed mechanical transmission system that passes between the input and output ends of the a fluid transmission mechanism that connects the input/output shaft of the other fluid pump/motor to the third input/output end and forms a variable speed fluid transmission system with both pumps/motors; and the low speed machine. a clutch on the low speed side that connects and separates the transmission end of the transmission system from a common rotating element provided on the input side or the output side;
and a high-speed side clutch that brings the transmission end of the high-speed side mechanical transmission system into contact with and away from the common rotating element, and by switching both the clutches in a reverse manner, either the low-speed mode or the high-speed mode can be set. It is configured so that you can select.

By the way, in such a continuously variable transmission, in an operating region where the speed ratio represented by output rotational speed/input rotational speed is smaller than the intermediate setting speed ratio where the speeds of both transmission ends are equal, the low speed side clutch Please select the low speed mode to connect only the above mentioned.

When the speed ratio increases and reaches the intermediate speed ratio, it is common to connect the high speed clutch and release the low speed clutch to shift to the high speed mode. When shifting from high speed mode to low speed mode, the opposite operation is performed.

However, in such a system, there are very few opportunities to stop the hydraulic transmission system, which has lower efficiency than a mechanical transmission system, and this makes it difficult to further improve the efficiency of the entire continuously variable transmission.

In such devices, a pressure difference almost always occurs between the circuits of the fluid transmission system, so the durability of the fluid pump/motor and its attached equipment that make up the fluid transmission system must be evaluated. The problem is that it is difficult to improve.

Therefore, when the speed ratio has recently reached an operating state in which the speed ratio approaches the intermediate set speed ratio by more than a certain level, the displacement of the fluid pump/motor is controlled and both clutches are connected to the intermediate lock. A device has been developed in which the displacement of the fluid pump/motor is controlled so that the differential pressure between the circuits of the fluid transmission system becomes approximately zero in this intermediate lock-up mode. .

According to such a configuration, the fluid pump/motor forming the fluid transmission system can be kept in a rest state in the above-mentioned intermediate lockup mode.

[Problems to be Solved by the Invention] However, while operating in such an intermediate lock-up mode, the gear ratio of the continuously variable transmission is fixed;
The speed ratio is maintained at the intermediate set speed ratio. Therefore, only by adjusting the gear ratio of the continuously variable transmission, control for converging the rotational speed of the engine to the target rotational speed must be interrupted. Therefore, even if there is no change in the load resistance of the vehicle, the engine rotational speed will increase by the increase in efficiency of the continuously variable transmission, and the vehicle speed will increase.In order to maintain the vehicle speed, the driver must: The problem is that you have to release the accelerator a little.

The present invention aims to solve these problems.

Means for Solving Problem E] In order to achieve the above object, the present invention employs the following configuration.

That is, the drive system with a continuously variable transmission according to the present invention is equipped with the above-mentioned continuously variable transmission, and the driving system is such that the driving system reaches an operating state in which the speed ratio approaches the intermediate set speed ratio by a certain amount or more. In this case, the displacement volume of the fluid pump/motor is controlled to enter an intermediate lock-up mode in which both clutches are connected, and in this intermediate lock-up mode, the differential pressure between the circuits of the fluid transmission system is reduced. intermediate lock-up means for controlling the displacement of the fluid pump/motor so that it becomes approximately zero; a displacement transmission element for transmitting a throttle operation amount to a fuel control end of the engine; and an intermediate lock-up means interposed in the middle of the displacement transmission element. The present invention is characterized by comprising transmission displacement control means for correcting the displacement to be transmitted in the intermediate and lock-up modes to converge the rotational speed of the engine to a target rotational speed at which fuel efficiency is minimized.

[Function] When the speed ratio approaches the intermediate setting speed ratio by a certain value or more during operation in the low speed mode or the high speed mode, in other words, when the rotational speed difference between the low speed side clutch and the high speed side clutch approaches a certain value or less In this case, the continuously variable transmission control that sequentially changes the gear ratio in the direction of bringing the actual engine speed closer to the target rotation speed is interrupted, and the displacement of the fluid pump/motor is controlled so that both clutches are synchronized. is forced into an intermediate lockup mode in which both clutches are engaged together. In this intermediate lockup mode, the differential pressure between the high and low circuits is controlled to be approximately zero. Therefore, leakage losses and pressure dependent torque losses within the fluid pump/motor are reduced. That is, the energy loss in this hydrodynamic transmission system is significantly reduced, and it becomes possible to transmit power substantially only through the mechanical transmission system. Therefore, in this intermediate lock-up mode, the transmission efficiency of the continuously variable transmission is improved and both fluid pumps/motors are substantially completely relieved from the load.

In this intermediate lock-up mode, the operational displacement transmitted from the driver to the fuel control end of the engine via the displacement transmission element is adjusted by the transmission displacement control means, and the rotational speed of the engine is adjusted to the target rotation speed that provides the best fuel efficiency. It is controlled to converge to the speed.

Therefore, in the intermediate lockup mode in which continuously variable speed control cannot be performed, the engine can be operated at a rotational speed corresponding to the accelerator opening. Therefore, it is possible to set the speed so that there is no change in speed before and after lock-up, and the driver is not forced to perform unnecessary accelerator operations.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 9.

The drive system of this embodiment is configured to transmit the output of the engine (2) to the running wheels (2) via a continuously variable transmission (2) and a final reduction gear (2).

As schematically shown in FIG.
, a low-speed mechanical transmission system a having second and third input/output ends 1.2.3 and passing between the first input/output end 1 and the second input/output end 2; A differential gear mechanism 4 that forms a high-speed mechanical transmission system in parallel that passes between the first input/output end 1 and the third input/output end 3;
The input/output shaft 7a of one fluid pump/motor 7 is connected to the second input/output end 2 of the fluid pump/motor 7 via a gear 5.6, and the input/output shaft 7a of the other fluid pump/motor 8 is connected to the third input/output end 3 of the fluid pump/motor 7. A fluid transmission mechanism 12 which connects the output shaft 8a via a gear 9.11 and forms variable speed fluid transmission systems A and B by these pumps/motors 7.8, and the low speed mechanical transmission system a. A clutch 14 on the low speed side that brings the transmission end of the mechanical transmission system into contact with and away from the center boss 13, which is a common rotating element, and a clutch 15 on the high speed side that brings the transmission end of the mechanical transmission system on the high speed side into contact with and away from the center boss 3. It is equipped with Then, the center boss 13 is connected to the output shaft 18 via gears 16 and 17.
is connected to.

The differential gear mechanism 4 is of a planetary gear type in which a sun gear 22 is disposed inside a plurality of planetary gears 21 arranged at equal intervals in the circumferential direction, and a ring gear 23 is meshed with the outside. Then, the center of the gear retainer 24 that supports each of the planetary gears 21 is set at the first input/output end 1.
An input shaft 25 connected to the engine (2) is provided at this input/output terminal 1. Further, the tip of the support shaft 22a of the sun gear 22 is the second input/output end 2, and the gear 5 is fixed to this input/output end 2. Further, the tip of the boss portion 23a of the ring gear 23 is the third input/output end 3, and the gear 9 is provided at the input/output end 3.

Therefore, the mechanical transmission system a on the low speed side is composed of the planetary gear 21, the sun gear 22, the gear 5, the gear 6, the forward clutch 26, the gear 28, and the gear 29, which will be described later. The boss portion 29a of 29 is
It plays a role as a transmission end of the mechanical transmission system a.

On the other hand, the mechanical transmission system on the high-speed side is composed of the planetary gear 21 and a ring gear 23, and the boss portion 23a of the ring gear 23 serves as a transmission end of the mechanical transmission system. .

Further, the fluid transmission mechanism 12 has a variable displacement fluid pump/motor 7 and a variable displacement fluid pump/motor 8 connected in series via a hydraulic circuit 31 similar to the normal H8T. The input/output shaft 7a of the fluid pump/motor 7 is connected to the support shaft 22a of the sun gear 22 via a gear 6.5, and the input/output shaft 8a of the fluid pump/motor 8 is connected to a gear 11.9. The ring gear 23 is connected to the ring gear 23 via the ring gear 23. Note that 32 is a boost pump connected to the hydraulic circuit 31.

An output direction switching mechanism 33 is interposed between the second input/output end 2 of the differential gear mechanism 4 and the one fluid pump/motor 7. The output direction switching mechanism 33 has a gear 6
is connected to the input/output shaft 7a of one fluid pump/motor 7 via the forward clutch 26, and the gear 6
A one-way clutch 35 is provided between the fixed member 34 and the fixed member 34. The one-way clutch 35 is configured so that, for example, a pawl 37 pivotally attached to the fixed member 34 can be engaged with the model wheel 36, and does not restrict the rotation of the gear 6 when moving forward, and does not restrict the rotation of the gear 6 when moving backward. The rotation of the second output end 2 of the differential gear mechanism 4 is restricted by prohibiting rotation in the direction. As each of the clutches 14, 15, and 26, a wet or dry multi-plate clutch, or a so-called synchromesh type power disconnection mechanism can be used. And these clutches 14.15.2
6 can be operated intermittently by actuators 41, 42, and 43.

In addition, this drive system transmits the amount of operational displacement applied to the accelerator pedal 51 via an accelerator wire 58, which is a displacement transmission element, to a fuel control end of the engine (2), such as a throttle valve 59 for opening and closing a throttle valve 59 of a carburetor. By transmitting the signal to the operating shaft 59a, the output of the engine I can be controlled. Note that the accelerator wire 58 is connected to a wire front section 58a connected to the accelerator pedal 51 and to the throttle operation shaft 5.
It is divided into a wire rear section 59b connected to wire 9a. A displacement adjusting device 60 is interposed between the wire front stage portion 59a and the wire rear stage portion 59b, and serves as a transmission displacement control means in cooperation with a computer to be described later.

The displacement adjustment device 60, as shown in FIGS. 4 to 7,
The operation input to the input side is differentially distributed to the first and second
The planetary differential mechanism 61 is configured to output from the output end of the planetary differential mechanism 61, and the fixing mechanism 62 fixes the second output end of the planetary differential mechanism 61 so that the position thereof can be changed. Hereinafter, the configuration will be explained in detail based on FIGS. 4 to 7. first,
The planetary differential mechanism 61 is disposed in the center of a box-shaped case 63, and one side wall 63a of the case 63 supports the wire front section 58a of the accelerator wire 58, and the other side wall 63b perpendicular thereto supports the accelerator. A rear wire portion 58b of the wire 58 is supported. That is, the wire front section 58a and the wire rear section 58b are slidably housed within the wire tubes 64t and 642, respectively, and the wire tubes 64. ．． The end of 64□ is connected to the side wall 63a via the holder 65+ and 652.

It is attached to 63b. Then, the wire front section 58
The terminal end of the wire a is connected to a locking part 66a provided on the outer periphery of an input pulley 66 which forms the input side of the planetary differential mechanism 61, and the starting end of the wire rear part 58b forms the first input side. It is connected to a locking portion 67a provided on the outer periphery of the output pulley 67, and each wire 58a, 58b is wound around the respective pulley 66, 67. Planetary differential mechanism 61
As shown in FIGS. 5 and 6, the ring gear 68
and the sun gear 6 disposed at the axial center of this ring gear 68.
9, and a gear retainer 71 rotatably provided with its axes aligned with the sun gear 69 and the ring gear 68.
A plurality of planetary gears 72 are supported by the gear retainer 71 via shafts 71a and mesh with both the ring gear 68 and the sun gear 69. The input pulley 66 is fixed to the ring gear 68, and the output pulley 67 is attached to the support shaft 69a of the sun gear 69. Further, a hollow output shaft 73 forming a second output end is fixed to the lower end of the gear retainer 71, and this output shaft 73 is connected to the boss portion 6 of the case 63.
3c is rotatably supported via a bearing 73 on the inner circumference. □The ring gear 68 is connected to the gear retainer 7 integrated with the output shaft 73 via a bearing 75.
The support shaft 69a of the sun gear 69 is rotatably supported by the output shaft 73 and the gear retainer 71 via bearings 76 and 77.

This output shaft 73 is locked by the fixing mechanism 62 so that its position can be adjusted. As shown in FIG. 7, the fixing mechanism 62 is constructed by fitting a piston 82 operated by pilot pressure taken out from the hydraulic circuit 31 into a cylinder 81 formed integrally with the boss portion 63C of the case 63. The pinion part 8 has a rack part 83 provided on the outer periphery of the piston 82 and a pinion part 8 carved on the outer periphery of the output shaft 73.
It meshes with 4. Specifically, the cylinder 81 is provided in a direction perpendicular to the output shaft 73, and lids 85, 86 are screwed onto both ends of the cylinder 81 in a liquid-tight manner. The piston 82 has a cylindrical shape with a bottom, and the coil spring 8
7 in the direction of one lid body 85. A pilot pressure introduction port 88 is provided in one of the lids 85, and boost pressure is introduced into a pressure guiding chamber 89 formed between the lid 85 and the piston 82 via a high-speed solenoid valve 90. That's what I do.

Therefore, when the high-speed solenoid valve 90 is closed, the piston 82 of the fixing mechanism 62 is held in a position where it is brought into contact with one lid body 85 by the biasing force of the spring 87, and the planetary difference The output shaft 73 of the moving mechanism 61 is locked at a prescribed fixed position. Therefore, the planetary gear 72 is held at a predetermined standby position, and the accelerator pedal 5
The operation amount of 1 is sequentially transmitted as it is from the manual pulley 66 and the ring gear 68 to the sun gear 69 via the planetary gear 72. And the support shaft 69a of the sun gear 69
An output pulley 67 fixed to the upper end of the throttle valve 59 rotates in a direction opposite to the human power, and the opening of the throttle valve 59 is controlled in accordance with the amount of operation of the accelerator wire 58.

On the other hand, when the high-speed solenoid valve 90 is opened and boost pressure is introduced into the pressure guiding chamber 89 of the fixing mechanism 62, the piston 82
moves against the biasing force of the spring 87, and the output shaft 73 of the planetary differential mechanism 61, which engages with the rack portion 83 of the piston 82, rotates around its axis within a predetermined angular range.

Along with this, the position of the planetary gear 72 pivotally supported by the gear retainer 71 changes, and the amount of output displacement from the sun gear 69 is reduced. That is, the input pulley 6
The operation amount of the accelerator pedal 51 transmitted to the throttle valve 6 is subtracted by an amount corresponding to the amount of change in the fixed position of the output shaft 73, and is output from the output pulley 67, and the opening degree of the throttle valve 59 is controlled.

Furthermore, the actuator 41.4 of the continuously variable transmission H
2.43.46 and an actuator 44.4 for changing the displacement of said hydraulic pump/motor 7.8.
5, and the high-speed solenoid valve 90 are controlled by a computer 91.

The computer 91 is constituted by a normal microcomputer system including a central processing unit 92, various types of memories 93, and an interface 94. The interface 94 receives a signal p from a rotation speed sensor 95 for detecting the output rotation speed, and a rotation speed sensor 9 for detecting the input rotation speed.
6, a signal r from the pressure sensor 97 provided in the circuit portion 31a of the hydraulic circuit 31, which becomes high pressure when the low speed mode is selected, and a signal r from the pressure sensor 97, which becomes high pressure when the high speed mode is selected. A signal S from a pressure sensor 98 provided in the circuit portion 31b and a signal t corresponding to the accelerator operation amount for controlling the output rotation of the engine I are respectively input. Further, from this interface 94, the actuator 41 of the low speed side clutch 14 is connected.
A signal U for operating the actuator 42 of the high-speed side clutch 15, a signal W for operating the actuator 43 of the forward clutch 26, and a signal W for operating the actuator 43 of the forward clutch 26. A signal XSy for operating the actuator 4'4.45 for adjusting the displacement volume, a signal 2 for operating the actuator 46, and a signal g for controlling the high-speed solenoid valve 90 are output. It looks like this.

In the memory 93 of this computer 91, there are programs related to control as shown in FIG. programs related to capacity control and transition control from high-speed mode to intermediate lock-up mode, or
As schematically shown in FIG. 8, a program to be executed in the intermediate lockup mode is included.

Next, the operation of the drive system when the vehicle is moving forward (with the forward clutch 26 connected and the clutch 35 released) will be described.

In an operating range where the speed ratio represented by the output rotational speed/manual rotational speed is smaller than the intermediate setting speed ratio e, the low speed mode is in which only the low speed side clutch 14 is connected. Specifically, the speed ratio is sequentially calculated based on the output rotation speed detected by the rotation speed sensor 95 and the input rotation speed detected by the rotation speed sensor 96.

The intermediate setting speed ratio e corresponds to the speed ratio in a state where the speeds of the transmission end of the mechanical transmission system a on the low speed side and the transmission end of the mechanical transmission system on the high speed side are equal. In this low speed mode, the input side and output A portion of the input power is directly transmitted to the output shaft 18 through this mechanical transmission system a. At this time, the one fluid pump/motor 7 functions as a motor, and the other fluid pump/motor 8 functions as a pump.

That is, the rotational force of the third input/output end 3 of the differential gear mechanism 4 is transmitted to the output shaft 18 through the hydraulic transmission system A formed between the pump/motor 7.8. In this low speed mode, the displacement volume of the other fluid pump/motor 8 is increased as shown in FIG. By gradually decreasing the displacement volume of the motor 7, the rotational speed of the output shaft 18 relative to the rotation of the input shaft 25 increases. The displacement volume of the fluid pump/motor 7.8 is controlled by a target rotation speed SD corresponding to the accelerator operation amount.
An operation command signal is output to the actuators 44 and 45 so that the actual rotational speed SE of the engine I detected by the rotational speed sensor 56 becomes equal. Note that the target rotational speed SD corresponds to the rotational speed of the engine I that provides the best fuel efficiency corresponding to each accelerator operation amount, and is determined in advance through experiments, etc., and is stored in the memory 93 in the form of a table. It is. Therefore, the target rotational speed SD in each driving state is selected based on the signal t corresponding to the accelerator operation amount that is sequentially input.

In such a low speed mode, when the rotational speed difference between the low speed side clutch 14 and the high speed side clutch 15 becomes smaller than a certain value, the mode shifts to the intermediate lockup mode. That is, when shifting to the intermediate lockup mode, the displacement volume of the fluid pump/motor 7 is controlled to synchronize the low speed side clutch 14 and the high speed side clutch 15,
Thereafter, not only the low-speed side clutch 14 but also the high-speed side clutch 15 are connected to lock the speed ratio to the intermediate set speed ratio e, . Immediately thereafter, the displacement volume of the fluid pump/motor 7 is controlled to reduce the differential pressure between the circuits of the fluid transmission system ASB, that is, the circuit section 31a.
The differential pressure between the pressure PA of the circuit section 31b and the pressure PB of the circuit section 31b is made zero. Therefore, this control is carried out by pressure sensors 5 provided in both circuit portions 31a and 31b of the fluid transmission mechanism 12.
7. Actuator 4 so that the detected values of 58 are equal
Activate 4.

In this intermediate lockup mode, the eighth
Repeat the control shown in the figure.

That is, first, in step 101, the rotational speed sensor 9
A set value α in which the value (SE/SD) obtained by dividing the actual rotational speed SE of the engine I detected by 6 by the target rotational speed SD predetermined in correspondence with the optimal fuel efficiency curve Q, etc. is larger than l. If it is determined that the value has exceeded the value, the process proceeds to step 102 and shifts to the high speed mode, but if it is determined that the value has not exceeded -1, the process proceeds to step 103. In step 103, it is determined whether the above-mentioned value (SE/SD) is smaller than the set value β, which is less than 1, and if it is determined to be smaller, the process proceeds to step 104 to return to the low speed mode. , if it is determined that it is not small, the process proceeds to step 105. In addition,
When the above value (S E / S D) exceeds the set value α, the operator suddenly decreases the amount of accelerator operation, thereby causing the target rotation speed SD to temporarily fall below the actual rotation speed SE. This includes both a state in which the actual rotational speed SE suddenly suddenly increases due to a sudden decrease in the load on the output side even though the operator maintains the amount of accelerator operation substantially constant. In such a case, it is better to increase the load on the engine itself, so the lockup state in the intermediate lockup mode is released and the mode is shifted to the high speed mode. In this case, the displacement volume of one fluid pump/motor 7 is further increased by a slightly larger amount to reduce the transmission torque from the low-speed mechanical transmission system a to the center boss 13 to zero, and then the low-speed side Release clutch 14. In addition, the case where the above value (SE/SD) becomes smaller than the set value β means that even though the operator suddenly increases the amount of accelerator operation, the rotational speed of engine I remains at the corresponding value. This includes both a state in which the actual rotational speed SE has not increased to the maximum speed, and a state in which the operator maintains the accelerator operation amount approximately constant, but the actual rotational speed SE has suddenly decreased due to a sudden increase in the load on the output side. . In such a case, it is necessary to reduce the load on the engine (2), so the lock-up state in the intermediate lock-up mode is released and the mode is shifted to a low-speed mode. Therefore, during this transition, the displacement volume of one fluid pump/motor 7 is slightly reduced (and the center boss 13 of the mechanical transmission system on the high-speed side is reduced).
After reducing the transmission torque to zero, the high-speed side clutch 15
Release.

On the other hand, in this intermediate lockup mode, if the process proceeds to step 105, the pressure PA in one circuit portion 31a of the fluid transmission mechanism is changed to the pressure P in the other circuit portion 31b.
, and if it is determined to be larger, the process advances to step 106 and the high-speed side fluid pump/
The displacement volume of the motor 7 is controlled in the increasing direction, and the process moves to step 110. If it is determined that the size is not large, the process advances to step 107. In step 107, it is determined whether the pressure P in the other circuit portion 31b is greater than the pressure PA in the one circuit portion 31a, and if it is determined to be greater, the process proceeds to step 108 to The displacement volume of the fluid pump/motor 7 is controlled in a decreasing direction, and the process moves to step 110. If not, it is determined that the two pressures PAsP are equal, and step 10
Proceed to step 9. In step 109, the fluid pump/motor 7
The control of the displacement volume is stopped and the process proceeds to step 110. In step 110, it is determined whether the rotational speed SE of the engine (2) is greater than the target rotational speed SD, and only when it is determined that the rotational speed SE is greater than the target rotational speed SD, the process proceeds to step 111. In step 111, the high speed solenoid valve 90
to be established.

The above routine is then repeatedly executed at minute time intervals.

Therefore, in this intermediate lock-up mode, the speed ratio of the continuously variable transmission (2) is fixed at the intermediate setting speed ratio 'effl, and both circuit portions 3 of the fluid transmission mechanism 12 are
Not only is the differential pressure between 1a and 31b maintained at zero, but by adjusting the displacement of the accelerator wire 58, the actual rotational speed SE of the engine I is adjusted to the target rotational speed SD determined in accordance with the accelerator operation amount. It will be controlled to converge.

Even when the above control is performed, when a sudden situation change as mentioned above occurs, the engine rotation speed S
Since E temporarily deviates from the target rotational speed SD, it is possible to switch from intermediate lockup mode to low speed mode or high speed mode.

When shifting to the high speed mode, a mechanical transmission system is formed that passes between the first input/output end 1 and the third input/output end 3 of the differential gear mechanism 4. A portion of the power is transmitted directly to the output shaft 18 through this mechanical transmission system. At this time, the one fluid pump/motor 7 functions as a pump, and the other fluid pump/motor 8
acts as a motor. That is, ``the differential gear mechanism 4
The rotational force of the second input/output end 2 of the fluid pump/
It is transmitted to the output shaft 18 through a fluid transmission system B formed between the motor 7 and the other fluid pump/motor 8. In this high-speed mode, the displacement volume of the one fluid pump/motor 7 is gradually increased as shown in FIG. By gradually decreasing the displacement volume, the rotational speed of the output shaft 18 relative to the rotational speed of the input shaft 25 increases.

In this case, control of the displacement volume of the fluid pump/motor 7.8 is also performed based on the target rotation speed SD corresponding to the accelerator operation amount and the actual rotation speed SE of the engine I detected by the rotation speed sensor 56. This is done by outputting actuation command signals to the actuators 44 and 45 so that they are equal.

In such a high-speed mode, if the rotational speed difference between the low-speed clutch 14 and the high-speed clutch 15 becomes smaller than a certain value, a transition is made to the intermediate lock-up mode using the same procedure as described above.

However, if it is like this, the low speed side clutch 1
When the rotational speed difference between the clutch 14 and the high speed clutch 15 becomes smaller than a certain value, the normal continuously variable speed control described above is interrupted and the clutch 14 and the high speed clutch 15
In addition, once the intermediate lock-up mode is set, the actual rotational speed SE and target rotational speed SD of the engine It is not possible to shift to high speed mode or low speed mode unless the deviation exceeds a certain width. Therefore, even if the vehicle is used for a relatively long period of time near the intermediate setting speed ratio e□, frequent switching of the low-speed side clutch 14 and the high-speed side clutch 15 can be prevented. Therefore, the clutch 1
4.15 and the life of the actuator 41.42 that operates this clutch 14.15 can be reasonably extended.

Moreover, in the intermediate lockup mode, the displacement volume of the fluid pump/motor 7 is controlled to control the circuit portion β1a.
and the circuit portion 31b is made to be approximately zero, thereby reducing the power transmission ratio of the hydraulic transmission systems A and B to zero and transmitting power only by the mechanical transmission systems a and b. It is meant to be transmitted. Although the efficiency of the fluid pump/motor 7.8 that makes up the fluid transmission systems A and B has increased in recent years, it is inferior to mechanical transmission, so the power transmission of the fluid transmission systems A and B is If an operating range in which the ratio is zero can be secured, system efficiency can be improved. That is, when the differential pressure between the circuits is controlled to be approximately zero as described above, the leakage loss inside the fluid pump/motor 7.8 is significantly reduced, and
Pressure-dependent torque losses are also reduced. Therefore, the energy loss in the hydraulic transmission systems A and B is reduced, and the transmission efficiency of the continuously variable transmission is increased (improved).In addition, the differential pressure between the circuits of the hydraulic transmission system can be reduced to almost zero during operation. The increased chance of damage also increases the durability of the fluid pump/motor 7.8 and its ancillary equipment.

FIG. 9 shows the mode switching manner of this embodiment when performing acceleration or deceleration, which is clearly different from the mode switching manner of the conventional and conventional examples shown in FIG.

Moreover, in this drive system, even in this intermediate lock-up mode, the rotational speed SE of the engine (2) can be controlled to converge to the target rotational speed SD, so that the engine (2) can always be operated in the desired state. Can be done. That is, in the intermediate lock-up mode, the speed ratio of the continuously variable transmission device (2) is fixed, so if the control by the transmission displacement control means is not performed, if the throttle operation amount is kept constant, the above-mentioned When the differential pressure (PAPB) between the circuit parts 31a and 31b of the continuously variable transmission device (3) is controlled to be zero, and the load torque changes from T to T11, as shown in FIG. The operating state of I is from point A along the constant throttle opening curve d1,
It shifts to 0 point, and the vehicle speed also changes (
This is because the speed ratio is constant). However, in this drive system, the transmission displacement by the accelerator wire 58 is sequentially corrected, so the actual throttle opening of the engine I is
It will be changed to the position corresponding to curve d2,
The operating state of engine I will shift from point A to point C. Therefore, the efficiency of the continuously variable transmission system can be improved, and if the load resistance of the vehicle does not change, the driver will not be forced to perform unnecessary accelerator operations, and the system efficiency can be improved effortlessly and effectively. This is something that can be improved.

Note that the differential gear mechanism is not limited to the planetary gear type as described above.

Further, the configuration of the fluid transmission mechanism is not limited to that of the embodiment described above, and various modifications can be made, for example, one fluid pump/motor may be of a fixed displacement type.

Further, in the embodiment described above, an input distribution system in which a differential gear mechanism is arranged on the input side has been described, but the present invention
The present invention can be similarly applied to output distribution systems.

Further, the configuration of the displacement transmission control means is not limited to the above-mentioned one, and various modifications can be made without departing from the spirit of the present invention, such as making it actuated by hydraulic pressure other than boost pressure. be.

[Effects of the Invention] As described in detail above, the present invention forcibly enters the intermediate lock-up mode when the switching range between the low-speed mode and the high-speed mode is approached, and closes the circuit between the fluid transmission system. Continuously variable speed not only reduces the differential pressure to almost zero, but also eliminates the need for the driver to perform unnecessary accelerator operations in the intermediate lock-up mode, effectively improving system efficiency. It is possible to provide a drive system with a device.

[Brief explanation of the drawing]

1 to 9 show an embodiment of the present invention, FIG. 1 is a system explanatory diagram, FIGS. 2 and 3 are explanatory diagrams for explaining control aspects, and FIG. 4 is a transfer displacement control diagram. A plan view of the displacement adjustment device which constitutes the main part of the means; FIG. 5 is a longitudinal sectional view of the device;
FIG. 6 is a schematic cross-sectional plan view showing the planetary differential mechanism portion of the device, FIG. 7 is a cross-sectional view taken along the line R-R in FIG. FIG. 9 is an explanatory diagram showing a mode switching aspect. FIG. 10 is an explanatory diagram corresponding to FIG. 9 showing a conventional mode switching mode. ■・・・Engine ■・・・Continuously variable transmission 4...
・Differential gear mechanism 7...One fluid pump/motor 8...Other fluid pump/motor 12...Fluid transmission mechanism 13...Common rotating element (center boss) 14...Low speed Clutch 15...High-speed clutch 51...Computer 56...Displacement transmission element (accelerator wire) 60...
Transmission displacement control means (displacement adjustment device, computer) a, b...Mechanical transmission system A, B...Fluid transmission system

Claims (1)

[Claims] A differential gear mechanism that forms a low-speed mechanical transmission system and a high-speed mechanical transmission system in parallel between input and output ends, and a pair of mechanical transmission systems in the middle of each of the mechanical transmission systems. A fluid transmission mechanism in which the input and output shafts of the fluid pump/motor are connected to form a variable speed fluid transmission system by these fluid pumps/motors, and the transmission end of the low speed mechanical transmission system is connected to the input side. or a low-speed side clutch that connects and separates from a common rotating element provided on the output side, and a high-speed side clutch that connects and disconnects a transmission end of the high-speed mechanical transmission system to and from the common rotating element, In an operating range where the speed ratio represented by output rotational speed/input rotational speed is smaller than the intermediate setting speed ratio where the rotational speed difference between the low-speed clutch and the high-speed clutch is zero, only the low-speed clutch is connected. A continuously variable transmission device is disposed at the rear of the engine, and is capable of selecting a low speed mode in which the speed ratio is higher than the intermediate set speed ratio, and a high speed mode in which only the high speed side clutch is connected in an operating range where the speed ratio is larger than the intermediate setting speed ratio. In the drive system, when the speed ratio reaches an operating state approaching the intermediate set speed ratio by a certain value or more, the displacement volume of the fluid pump/motor is controlled so that both the clutches are connected together. intermediate lock-up means for controlling the displacement volume of the fluid pump/motor so that the differential pressure between the circuits of the fluid transmission system becomes approximately zero in the intermediate lock-up mode; and a throttle; a displacement transmitting element that transmits a manipulated variable to a fuel control end of the engine; and a displacement transmitting element interposed in the middle of the displacement transmitting element, which corrects the displacement to be transmitted in the intermediate lockup mode and throttles the rotational speed of the engine. A drive system equipped with a continuously variable transmission, characterized in that it is equipped with a transmission displacement control means for converging to a target and rotational speed corresponding to the rotational speed.