JPH0582509B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydromechanical transmission that can be widely used in various industrial fields as a highly efficient continuously variable transmission.

[Prior Art] A so-called hydrostatic transmission (HST) is known as a continuously variable transmission using a fluid pump/motor. However, although this device has excellent continuously variable speed, the efficiency is not necessarily good and the speed range is not satisfactory. Therefore, by using the HST and the differential gear mechanism together and sharing the power transmission between the HST and the differential gear mechanism, it is possible to
A hydromechanical transmission (HMT) that combines the continuously variable speed characteristics of HST with the high efficiency of gear transmission has been developed and published {References,
Hydraulic Engineering (edited by Tomoo Ishihara, Asakura Shobo), Theory and Practice of Piston Pump Motors (edited by Sadao Ishihara, Corona Publishing). That is, this one has the first, second, and third
A low-speed mechanical transmission system having an input/output end and passing between the first input/output end and the second input/output end, or the first input/output end and the third input/output end. a differential mechanism that forms a high-speed mechanical transmission system that passes between the a fluid transmission mechanism that connects the input/output shaft of the other fluid pump/motor to the output end and forms a variable speed fluid transmission system by these pumps/motors; and a transmission end of the mechanical transmission system on the low speed side. a low-speed clutch that brings the transmission end of the high-speed mechanical transmission system into and out of contact with the common rotating element provided on the input side or the output side; and a high-speed clutch that brings the transmission end of the high-speed mechanical transmission system into contact with and separates from the common rotating element. By switching the two clutches in a reverse manner, either the low speed mode or the high speed mode can be selected.

However, with such a configuration, there is a problem in that a shock is likely to occur when switching modes.
In other words, this device directly transmits a portion of the input power to the output side via a mechanical transmission system using gears, etc., and outputs the remaining power via the fluid transmission system using the fluid pump/motor. It is adapted to be guided to the side and merged with the power of the mechanical transmission system. In this case, the fluid transmission system is
When a load is applied, the rotational output tends to lag behind that of a mechanical transmission system due to leakage of differential fluid inside the fluid pump/motor and the influence of elasticity of the hydraulic circuit. In such a configuration, as will be described later, the roles of the paired fluid pump/motor as pump and motor are exchanged when the mode is switched, so the effects of the delay described above may act in reverse. become. Therefore, for example, when switching from low-speed mode to high-speed mode, the moment when the rotational speed of the transmission end of the high-speed mechanical transmission system becomes the same as the rotational speed of the transmission end of the low-speed mechanical transmission system, or If the clutch for low speed is released and the clutch for high speed is connected at the same time after a certain period of time has passed after the transmission becomes the same, torque will not be transmitted from the mechanical transmission system on the low speed side to the common rotating element. This state is abruptly interrupted, and after instantly absorbing the buck-like irregular idling region of the entire system, the state shifts to a state where torque is transmitted from the high-speed mechanical transmission system to the common rotating element. Therefore, a large instantaneous mechanical shock often occurs during the switching.

[Problems to be Solved by the Invention] An object of the present invention is to reliably eliminate the problem of shock occurring during mode switching with a relatively simple configuration.

[Means for Solving the Problem] In order to achieve the above object, the present invention provides a hydromechanical transmission that employs the mode switching method as described above, in which the rotational speed of the transmission end of both mechanical transmission systems is adjusted. a speed detection means for detecting a torque transmission state at both said transmission ends; a torque detection means for detecting a state of torque transmission at said two transmission ends; and a torque detection means for connecting said two clutches when the rotational speeds of said transmission ends detected by said speed detection means become equal. and control means for correcting and controlling the gear ratio of the fluid transmission mechanism until the transmission states of the torques detected by the torque detection means are mutually switched, and at the time the correction is completed, releasing the clutch on the side where the transmitted torque is deenergized. It is characterized by having the following.

[Operation] In the low speed mode, the transmission end of the low speed mechanical transmission system passing between the first input/output end and the second input/output end of the differential mechanism is connected to the output side via the low speed clutch. Alternatively, it is connected to a common rotating element provided on the input side, and a portion of the input power is output directly through this mechanical transmission system. In addition, the remaining power is
is guided to the output side through a fluid transmission system formed by a fluid transmission mechanism, in which case the fluid pump/motor on one side acts as a motor and
The fluid pump/motor on the other side functions as a pump.

In addition, in the high-speed mode, the transmission end of the mechanical transmission system on the high-speed side that passes between the first input/output end and the third input/output end of the differential mechanism is connected to the common rotating element, and the input/output end is connected to the common rotating element. A portion of the power is output directly through this mechanical transmission system. Further, the remaining power is guided to the output side through a fluid transmission system formed by a fluid transmission mechanism, but in this case, the roles of each fluid pump/motor as a pump and a motor are reversed.

When switching from the low-speed mode to the high-speed mode, the following actions occur. That is, first, when only the low-speed clutch is engaged and the rotational speed of the traditional end of the high-speed mechanical transmission system becomes equal to the rotational speed of the transmission end of the low-speed mechanical transmission system, only the low-speed clutch is connected. The high-speed clutch also becomes connected. After that, the torque transmission state between the low-speed mechanical transmission system and the common rotating element disappears, and torque is transmitted between the high-speed mechanical transmission system and the common rotating element. , the transmission ratio of the hydrodynamic transmission system is corrected, and then the low speed clutch is released. When switching from high speed mode to low speed mode, the opposite effect takes place.

[Example] An example of the present invention will be described below with reference to FIGS. 1 and 2.

As schematically shown in FIG. 1, the hydromechanical transmission according to the present invention has first, second, and third input/output ends 1, 2, and 3. and the second input/output end 2, or the first input/output end 1 and the third input/output end 3.
A differential mechanism 4 forming a high-speed mechanical transmission system b that passes between 5a, and the input/output shaft 7a of a variable displacement fluid pump/motor 7 is connected to the third input/output end 3, so that both pumps/motors 5, 7
a fluid transmission mechanism 8 forming variable speed fluid transmission systems A and B, and the low speed mechanical transmission system a.
A mode switching mechanism 9 for selecting either a low speed mode in which the input side and the output side are directly connected via the mechanical transmission system b on the high speed side or a high speed mode in which the input side and the output side are directly connected via the mechanical transmission system b on the high speed side. It is equipped with the following.

The differential mechanism 4 is of a planetary gear type in which a sun gear 4b is disposed inside a plurality of planetary gears 4a provided at equal intervals in the circumferential direction, and a ring gear 4c is meshed with the outside. and a gear retainer 4d that supports each of the planetary gears 4a.
The center portion of the input/output shaft 1 is the first input/output shaft 1, and an input shaft 13 is provided at the input/output end 1. Further, the support shaft 4e of the sun gear 4b is used as the second input/output end 2, and a gear 14 is fixed to this input/output end 2.
Further, the boss portion 4f of the ring gear 4c is the third input/output end 3, and the gear 1 is connected to the input/output end 3.
5 is set.

Further, the fluid transmission mechanism 8 is one in which the fixed displacement type fluid pump/motor 5 and the variable displacement type fluid pump/motor 7 are connected in series via a hydraulic circuit 16 like a normal HST. The input/output shaft 5a of the fluid pump/motor 5 is directly connected to the sun gear 4b support shaft 4e, and the input/output shaft 7a of the fluid pump/motor 7 is connected to the ring gear 4c via a gear 17. There is.

The mode switching mechanism 9 also connects a low-speed gear 18 that meshes with the gear 14 of the second input/output end 2 and serves as a transmission end of the low-speed mechanical transmission system a, and an output shaft 19 that is a common rotating element. Clutch 2 for low speed between
1 is interposed between the high speed gear 22 which meshes with the gear 15 of the third input/output end 3 and becomes the transmission end of the high speed side mechanical transmission system b, and the output shaft 19. A clutch 23 is provided.

Such a transmission further includes speed detection means 24 for detecting the rotational speeds of the low speed gear 18 and high speed gear 22, which are the transmission ends of the mechanical transmission systems a and b, and When the rotational speeds of the gears 18 and 22 detected by the torque detection means 25 and the speed detection means 24 become equal, both the clutches 21 and 23 are connected and the torque detection means 25 detects the transmission state. control means 26 for correcting and controlling the gear ratio of the fluid transmission mechanism 8 until the transmission states of the torques transmitted are mutually switched, and then releasing the clutch 21 or 23 on the side where the transmitted torque is deenergized when the correction is completed. ing.

To be more specific, the speed detection means 24 includes a pair of speed sensors 24a and 24b.
One speed sensor 24a detects the rotational speed of the low speed gear 18, and the other speed sensor 24b detects the rotational speed of the high speed gear 22, and converts them into electrical signals.

Further, the torque detection means 25 includes a pair of pressure sensors 25a and 25b. One pressure sensor 25a is connected to a low speed high pressure circuit section 16a in the hydraulic pressure circuit 16 of the fluid transmission mechanism 8, that is,
When the low-speed mode is selected, the pressure in the high-pressure side of the circuit is detected and converted into an electrical signal. Moreover, the other pressure sensor 25b is
The pressure of the high-pressure circuit section 16b at high speed in the hydraulic pressure circuit 16 of the fluid transmission mechanism 8, that is, the pressure of the circuit section that becomes high pressure when the high-speed mode is selected, is detected and converted into an electrical signal. There is.

The control means 26 also includes an actuator 27 for changing the displacement of the variable displacement fluid pump/motor 7, and a computer 28 for controlling the actuator 27 and the clutches 21, 23. The actuator 27 is
If the fluid pump/motor 7 is of a swash plate type or an oblique shaft type, the swash plate angle or the oblique axis angle is changed, and the fluid pump /motor 7
is radial piston type or JP-A-58-77179
In the case of a static pressure balanced type as shown in the above publication, the eccentric position of the pintle is changed. Further, the computer 28
is constituted by an ordinary microcomputer system comprising a central processing unit (CPU) 29, various types of memory 30, and an interface 31, and the interface 31 includes the respective rotation sensors 24a. , 24b and the respective pressure sensors 25a, 25b, and signals from the actuator 27 and the clutches 21, 25b are input from the interface 31.
A command signal to be supplied to 23 is output. A part of the memory 30 of this computer 28 stores the following program. That is, first, the clutch 21 for low speed
The rotational speed of the high-speed gear 22 approaches the rotational speed of the low-speed gear 18 from the low-speed mode in which the clutch 22 is engaged, and when the rotational speeds finally match, the high-speed clutch 2
3 also outputs a connection command signal, and both clutches 21,
23 to the connected state. Then, the detected values P of both the pressure sensors 25a and 25b at that time,
Q is temporarily stored in the memory 30. After that, a differential command signal for correction is output to the actuator 27, and the actuator 2
Activate 7. The operation is continued until the detected values of both pressure sensors 25a and 25b are reversed to the values stored in the memory 30 earlier.
When the detected value is reversed, the actuator 27 is stopped, the low speed clutch 21 is released, and the mode is shifted to the high speed mode. Also, when switching from high-speed mode to low-speed mode, follow the procedure described above to release clutch 2.
1 and 23 and actuation of the actuator 27.

In this embodiment, rotational power from an engine or the like is input to the input shaft 13 provided at the first input/output end 1 of the operating mechanism 4, and the rotational power is input to the differential mechanism via the mode switching mechanism 9. Output shaft 13 connected to the second or third input/output end 2, 3 of 4
Rotational power is output from the motor and transmitted to the drive wheels of the vehicle.

Next, the differential of this embodiment will be explained.

In the low speed mode in which the low speed clutch 21 is connected and the high speed clutch 23 is released, the first
The input side and the output side are directly connected through a mechanical transmission system a on the low speed side that passes between the input/output end 1 and the second input/output end 2 of the machine, and a part of the input power is transmitted to the machine. It is directly transmitted to the output shaft 19 through the transmission system a. At this time, as shown in FIG. 2, the variable displacement fluid pump/motor 7 functions as a pump, and the fixed displacement fluid pop/motor 5 functions as a motor. That is, the rotational force of the third input/output end 3 of the differential mechanism 4 is transmitted to the fluid transmission system A formed between the variable displacement fluid pump/motor 7 and the fixed displacement fluid pump/motor 5. is transmitted to the output shaft 19 through. In this low speed mode, by increasing the capacity of the variable displacement fluid pump/motor 7, the rotational speed of the output shaft 19 relative to the rotational speed of the input shaft 13 increases. Become. In other words, the variable displacement fluid pump/motor 7
When the capacity of It's stopped. As the capacity of the fluid pump/motor 7 increases, the rotational speed of the third input/output end 3 relatively decreases, and the rotational speed of the second input/output end 2 decreases. It will increase relatively.

Then, when the rotational speeds of the second input/output terminal 2 and the third input/output terminal become equal, a switching operation as described later is executed, and the mode is switched to the high speed mode.

In this high-speed mode, a mechanical copper system b is formed that passes between the first input/output end 1 and the third input/output end 3 of the differential mechanism 4, and a part of the input power is It is directly transmitted to the output shaft 19 through this mechanical transmission system b. At this time, as shown in FIG. 2, the variable displacement fluid pump/motor 7 functions as a motor, and the fixed displacement fluid pump/motor 5 functions as a pump. That is, the rotational force of the second input/output end 2 of the differential mechanism 4 is transmitted to the fluid transmission system B formed between the fixed displacement fluid pump/motor 5 and the variable displacement fluid pump/motor 7. is transmitted to the output shaft 19 through. In this high-speed mode, by decreasing the capacity of the variable displacement fluid pump/motor 7, the rotational speed of the output shaft 19 relative to the rotational speed of the input shaft 13 increases. become. In other words, by decreasing the capacity of the fluid pump/motor 7 operating as a motor, the rotational speed of the third input/output 3 is relatively increased, and the rotation speed of the second input/output terminal 3 is increased. 2 will be relatively reduced.

Here, the operation when switching from low speed mode to high speed mode will be explained. The rotational speed of the high-speed gear 22 approaches the rotational speed of the low-speed gear 18, and when the rotational speeds finally match, a connection command signal is output from the control means 26 to the high-speed clutch 23, and both clutches 21, 23 becomes connected. Then, both the pressure sensors 25 at that time
The detected values P and Q of a and 25b are temporarily stored in the memory 30. However, at this stage, still
Torque is transmitted from the low-speed gear 18 of the low-speed mechanical transmission system a to the output shaft 19, which is a common rotating element, and the torque is not transmitted from the high-speed gear 22 of the high-speed mechanical transmission system b to the output shaft 19. Not yet. Thereafter, a correction operation command signal is outputted from the computer 28 to the actuator 27, and the actuator 27 is operated in the direction of decreasing the capacity. And its operation is
The process continues until the detected values of both pressure sensors 25a and 25b are reversed to the values stored in the memory 30 earlier. In other words, the detected value of the pressure sensor 25a is P
(high pressure) and the detection value of pressure sensor 25b is Q (low pressure)
The capacity of the fluid pump/motor 7 is corrected from the state in which the detected value of the pressure sensor 25a becomes Q and the detected value of the pressure sensor 25b becomes P. In the process, the fluid pump/
The roles of the motors 5 and 7 as a pump and a motor are completely switched, and the torque that was being transmitted from the low speed gear 18 to the output shaft 19 disappears, and the torque is transmitted from the high speed gear 22 to the output shaft 19. The state will be as follows. At this point, the corrective operation of the actuator 27 is stopped, the low speed clutch 21 is released, and the mode shifts to the high speed mode.
Also, when switching from high speed mode to low speed mode, clutches 21 and 2 should be
3 switching and actuation of actuator 27 are performed.

Therefore, with such a device, the rotational speed and torque are continuously connected at the mode switching point, and smooth mode switching without shock is possible. Furthermore, since this device only controls the switching timing of the clutches 21 and 23 and slightly corrects the gear ratio of the fluid transmission mechanism 8, the configuration is relatively simple and easy to implement. It is.

Note that the differential mechanism is not limited to a planetary gear type, but if it is a planetary gear type, it becomes easy to achieve compactness.

Furthermore, the fluid transmission mechanism is of course not limited to the one described above, and may be modified in various ways without departing from the spirit of the present invention, for example, the paired fluid pump/motor may both be of variable displacement type. Deformation is possible.

Furthermore, the configuration of the torque detection means is of course not limited to the one described above. For example, the torque acting on the low-speed gear and the high-speed gear, which are the transmission ends of the mechanical transmission system, can be directly detected using a torque pickup. However, according to the pressure detection method as described above, switching of the torque transmission state can be easily and accurately detected.

Furthermore, the control means is not limited to one using an electronic computer, but may also be a fluid control device equipped with a hydraulic logic circuit.

Furthermore, in the embodiment described above, an input split system in which a differential mechanism was arranged on the input side was explained.
The present invention is not necessarily limited to this type of device, and can be similarly applied to, for example, a device using an output division method.

[Effects of the Invention] Since the present invention has the above-described configuration, it is possible to provide an excellent hydromechanical transmission that can reliably eliminate shocks that occur during mode switching with a relatively simple configuration. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a system showing an embodiment of the present invention;
FIG. 2 is an explanatory diagram of the operation of the same embodiment. DESCRIPTION OF SYMBOLS 1...First input/output end, 2...Second input/output end, 3...Third input/output end, 4...Differential mechanism, 5
...One fluid pump/motor, 5a...Input/output shaft, 7...Other fluid pump/motor, 7a...
Input/output shaft, 8...Fluid transmission mechanism, 18...Transmission end (low speed gear), 19...Common rotating element, 21...Low speed clutch, 22...Transmission end (high speed gear),
23... Clutch for high speed, 24... Rotation detection means, 25... Torque detection means, 26... Control means, a... Mechanical transmission system on low speed side, b... Mechanical transmission system on high speed side, A, B...Fluid transmission system.

Claims (1)

[Claims] 1 having a first, second, and third input/output terminal, and the first
A low-speed mechanical transmission system passing between the input/output end and the second input/output end, or the first input/output end and the third input/output end.
A differential mechanism that forms a high-speed mechanical transmission system that passes between the input and output ends of and 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 by both pumps/motors, and the low speed machine. A clutch for low speeds that brings the transmission end of the mechanical transmission system into contact with and leaves the common rotating element provided on the input side or the output side, and a clutch for high speeds that brings the transmission end of the mechanical transmission system on the high speed side into contact with and separates from the common rotating element. A hydromechanical transmission comprising a clutch and configured to be able to select either a low speed mode or a high speed mode by switching both clutches in a reverse manner, wherein both the mechanical transmissions speed detection means for detecting the rotational speed of a transmission end of the system; torque detection means for detecting a torque transmission state at both said transmission ends;
When the rotational speeds of the transmission ends detected by the speed detection means become equal, both the clutches are connected and the transmission ratio of the fluid transmission mechanism is changed until the torque transmission states detected by the torque detection means change. 1. A hydromechanical transmission comprising: control means for correcting and controlling the clutch on the side where the transmission torque is deenergized when the correction is completed.