JPH10205617A - Hydraulic control device for hydraulic clutch type transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To alleviate a gear change shock during a start, acceleration and deceleration, regarding the hydraulic control device of a hydraulic clutch type transmission for changing a travel speed via the selection of a hydraulic clutch. SOLUTION: A hydraulic fluid feed and discharge circuit for a plurality of hydraulic clutches 15 to 17 of a hydraulic clutch type transmission for changing a travel speed, is provided with the first direction selector valve 53 for selecting the feed of hydraulic fluid to the hydraulic clutches 15 to 17 in an alternative way. When the second direction selector valve 54 of oil pressure sensitive type to alternatively select the hydraulic fluid feed to a plurality of the forward travel hydraulic clutches 15 and 16 of the hydraulic clutch type transmission are selected from a low speed position S1 to a high speed position H, the second direction selector valve 54 automatically shifts up a gear from the low speed position S2 toward a high position S3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic clutch type transmission for changing the speed of a vehicle, which reduces a shift shock in the process of starting, accelerating, and decelerating and improving the ride comfort of an operator. It relates to a control device.

[0002]

2. Description of the Related Art Conventionally, a plurality of hydraulic clutches are arranged in a transmission case of a traveling vehicle, and a directional control valve is switched by a shift lever to selectively send hydraulic oil to each hydraulic clutch. 2. Description of the Related Art A hydraulic clutch type transmission that enables a plurality of speeds is known. For example, the technique of Japanese Utility Model Publication No. 6-18434. Further, selection of forward and reverse is performed by manual operation, the vehicle speed is detected by a sensor, a signal from the sensor is input to a control circuit, and it is determined whether the vehicle speed has reached a set speed,
2. Description of the Related Art There is known a technique in which a solenoid valve is switched by a signal from a control circuit so that forward and backward speeds are automatically switched between a low speed and a high speed. For example, there is a technique disclosed in Japanese Utility Model Application Laid-Open No. 61-189844.

[0003]

However, with the former technique, when the vehicle shifts from the neutral position to the high-speed position and starts, a high load is applied to the high-speed hydraulic clutch. The joining time becomes longer, and the clutch suddenly joins around the steep slope of the pressure increase curve of the hydraulic pressure supplied thereto, so that the starting shock may increase, and when switching from low speed to high speed during traveling, A time lag occurs, a shift shock occurs, and the traveling speed during shifting is unstable. In the latter case, an electronic control unit such as a vehicle speed sensor or a microcomputer is required, and a shift timing setting circuit,
It is necessary to add an arithmetic circuit for increasing or decreasing the speed, and the number of attached devices has increased, leading to an increase in cost.

[0004]

Means for Solving the Problems The present invention is configured as follows to solve the above-mentioned problems. That is, in the hydraulic oil supply circuit for the plurality of hydraulic clutches 15, 16, 17 in the hydraulic clutch type transmission for changing the vehicle speed, the first direction in which the hydraulic oil supply to the hydraulic clutches 15, 16, 17 is selectively switched. A switching valve 53 is provided, and a hydraulically responsive second direction switching valve 54 for selectively switching the supply of hydraulic oil to the first direction switching valve 53 and a plurality of hydraulic clutches 15 and 16 on the forward side of the hydraulic clutch type transmission is provided. When the first directional control valve 53 is in the high-speed position H,
The second directional control valve 54 is configured to automatically shift up from the low speed position S1 to the high speed position S3.

The back pressure chamber 6 of the second directional control valve 54
7, the hydraulic oil output when the first directional control valve 53 is set to the high-speed position H is applied via the throttle valve 91, so that the second directional control valve 54 sequentially starts from the low-speed position S1 and moves to the high-speed position S3. It is configured to automatically switch to.

The hydraulic oil supply / discharge circuit between the low-speed side hydraulic clutch 15 and the second direction switching valve 54 is provided with a hydraulic oil output when the first direction switching valve 53 is set at the low speed position L. In addition, each of the hydraulic oils output when the hydraulic oil is at the high-speed position H is constituted by two oil passages 72 and 76 that can be independently introduced. Check valve 6 that allows only oil flow to
2 is provided.

Further, a valve 63 for limiting the drain flow rate of the hydraulic clutch 15 on the low speed side when the first direction switching valve 53 is switched from the low speed position L to the high speed position H is provided. Further, a valve 100 for limiting the drain flow rate of the hydraulic clutch 16 on the high-speed side when the first direction switching valve 53 is switched from the high-speed position H to the low-speed position L is provided separately from the valve 63.

The back pressure chamber 6 of the second directional control valve 54
A check valve 90 that allows only oil flow in the direction of draining oil from 7 is provided in parallel with the throttle 91, and the first directional control valve 53 is moved from the high speed position H to the neutral position N or the low speed position. When switching from L to the neutral position N, the hydraulic oil of the engaged hydraulic clutches 15 and 16 is drained to the tank instantaneously.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the structure of an embodiment of the present invention. FIG. 1 is a skeleton diagram of a power transmission system equipped with a hydraulic clutch type transmission, FIG. 2 shows a hydraulic control device of the present invention, and a hydraulic circuit diagram when a first directional control valve is in a neutral position, and FIG. FIG. 4 is a hydraulic circuit diagram when the one-way switching valve is switched to the low-speed position, FIG. 4 is a hydraulic circuit diagram at a transition position when the first directional switching valve is switched from the low-speed position to the high-speed position, and FIG. FIG. 6 is a hydraulic circuit diagram when the valve is switched to the high-speed position, FIG. 6 is a hydraulic circuit diagram when the first directional control valve is in the high-speed position and the second directional control valve is in the process of switching, and FIG. 8 is a hydraulic circuit diagram showing a state in which the switching of the second direction switching valve at the position is completed, FIG. 8 is a hydraulic circuit diagram at a transition position where the first direction switching valve switches from the high speed position to the low speed position, and FIG. Switching valve at low speed FIG. 10 is a hydraulic circuit diagram in which the first directional control valve is in the low-speed position and the second directional control valve is in the process of switching, and FIG. 11 is a hydraulic circuit diagram in the same manner when the first directional control valve is in the low-speed position. FIG. 12 is a hydraulic circuit diagram showing a state in which the switching of the two-way switching valve has been completed. FIG. 12 shows the relationship between the clutch operating oil pressure and the clutch pressure-up time when the hydraulic clutch transmission is switched from the neutral position to the low speed position, the high speed position, and the low speed position. Diagram showing the relationship,
FIG. 13 is a diagram showing the relationship between the clutch operating oil pressure and the clutch pressure-up time when the hydraulic clutch transmission is switched from the neutral position or the low-speed position to the high-speed position.

Referring to FIG. 1, the structure of a power transmission to which the present invention is applied will be described. Power is transmitted from the crankshaft of the engine E to the hollow input shaft 2 via the clutch housing of the PTO clutch 1.
A PTO drive shaft 3 is rotatably inserted into the hollow input shaft 2, the tip of which is connected to the clutch plate of the PTO clutch 1, and the rear end side of which transmits power to a PTO shaft 4 protruding from the rear end of the transmission case. Can be A first transmission shaft 5 and a second transmission shaft 6 are arranged in parallel with the input shaft 2, and a gear 8 loosely fitted on the first transmission shaft 5 and a second transmission The gear 9 loosely fitted on the shaft 6 is always meshed. A clutch case 10 is fixed to the rear part of the input shaft 2, and a gear 11 is loosely fitted on the rear input shaft 2, and the loosely fitted gear 11 is fixed to a hollow output shaft 19. I have.
A high-speed hydraulic clutch 16 is formed between the gear 11 and the clutch case 10. The input shaft 2 is directly connected to the output shaft 19 by engaging the high-speed hydraulic clutch 16.

A clutch case 1 is provided on the first transmission shaft 5.
2, a reverse driven gear 13 and a gear 14 are fixedly mounted, and a low-speed hydraulic clutch 15 is provided between the clutch case 12 and the gear 8.
And the reverse driven gear 13 is a reverse drive gear 2 described later.
The gear 14 is always meshed with the gear 11. When the low-speed hydraulic clutch 15 is engaged,
The rotation of the input shaft 2 is reduced and transmitted to the output shaft 19.
A clutch case 20 and a reverse rotation drive gear 21 are fixed on the second transmission shaft 6, and a reverse hydraulic clutch 17 is formed between the clutch case 20 and the gear 9. When the reverse hydraulic clutch 17 is engaged, the rotation direction of the output shaft 19 can be reversed with respect to the input shaft 2.
As described above, a two-stage forward and one-stage reverse hydraulic clutch type transmission is configured.

The rear end of the output shaft 19 is spline-fitted to the front end of a hollow first transmission shaft 22 to transmit power. The first transmission shaft 22 is connected to the rear end of the PTO drive shaft 3. The PTO transmission shaft 26 is loosely fitted on the front half of the
A hollow third transmission shaft 24 is loosely fitted to the rear half of the O transmission shaft 26. Further, a second transmission shaft 23 is disposed in parallel with the first transmission shaft 22, and a fourth transmission shaft 25 is disposed so that its axis is aligned with the rear end of the second transmission shaft 23, and the fourth transmission shaft 25 is disposed. 25
A bevel pinion 29 is disposed at the rear end of the vehicle, and is connected to a large bevel gear of a differential gear device D for differentially connecting a pair of left and right rear wheels.

A four-stage first mechanical transmission is provided between the first transmission shaft 22 and the second transmission shaft 23, and a three-stage first mechanical transmission is provided between the third transmission shaft 24 and the fourth transmission shaft 25. A second stage mechanical transmission is provided. That is, sliders 31 and 32 are spline-fitted on the first transmission shaft 22 so as to be slidable and relatively non-rotatable. The sliders 31 and 32 have clutch teeth on both front and rear sides, respectively. The slider 31 is provided with a gear 33 that is loosely fitted on the first transmission shaft 22.
34, and can be engaged with one of the gears.
The gears can be engaged with one of the gears 35 and 36 loosely fitted on the second transmission shaft 22. The gear 33 always meshes with a gear 37 fixed on the second transmission shaft 23, and similarly, the gears 34, 35, 36 always mesh with gears 38, 39, 40 respectively fixed on the second transmission shaft 23. The gears 35, 36, 37 are engaged with each other, and the sliders 31, 32 are separately slid.
The four-speed shift can be obtained on the second transmission shaft 23 by selectively engaging with any one of 38.

At the rear end of the second transmission shaft 23, a gear 41 having clutch teeth on its side is fixedly provided. On the fourth transmission shaft 25, clutch teeth are provided on both front and rear sides. The slider 42 and the sliding gear 44 are slidably and spline-fitted so that they cannot rotate relative to each other. Slider 42
On the side, a gear 43 is loosely fitted on the fourth transmission shaft 25, while on the third transmission shaft 24, gears 45 and 46 that are always meshed with the gears 41 and 43 are fixedly mounted. Moving gear 4
A gear 47 meshable with the gear 4 is fixedly provided.

Thus, the slider 42 is moved to the gear 4
1, 43, or
The gear 47 is meshed with the sliding gear 44 so that the fourth transmission shaft 25 can perform three-stage shifting. A gear 49 is fixed on the fourth transmission shaft 25 to transmit power to the front wheel drive shaft 50 via a gear transmission mechanism. Then, power is transmitted from a bevel pinion 29 formed at the rear end of the fourth transmission shaft 25 to the differential gear device D, and is forwarded to the rear wheel 51 via the planetary reduction gear mechanism as a whole, with 14 forward steps and 7 reverse steps. It is configured to transmit the variable speed rotation power.

The present invention is a hydraulic control device for selectively engaging the low-speed hydraulic clutch 15 and the high-speed hydraulic clutch 16 in the hydraulic clutch type transmission, and will be described in order from the hydraulic circuit shown in FIG. Go. The discharge port of the hydraulic pump 52 driven by the crankshaft of the engine E is connected to the input port of the first directional control valve 53 via a main oil passage 70, and a common delay relief valve via a branch oil passage 69. 55. The first directional control valve 53 is a manual directional control valve having 7 ports and 4 positions. The reverse position R, the neutral position N, the low speed position L, and the high speed position H
The operation lever 5 provided at the four positions near the driver's seat of the vehicle
7 allows manual switching. When switching from the low-speed position L to the high-speed position H or from the high-speed position H to the low-speed position L, the excessive position K
The first directional control valve 53 is configured to always pass through.

The oil drain port on the primary side of the first direction switching valve 53 communicates with the tank 59 via an oil passage 73, and the other oil discharge port is connected to the delay relief valve 55 via an oil passage 77. It communicates with the pressure receiving chamber of the control piston. The four output ports on the secondary side of the first directional control valve 53 are respectively
The reverse clutch 17 communicates with the oil passages 71, 74, and 78 extending to the second direction switching valve 54 described below via the oil passage 80. A pilot oil passage 75 branches from the middle of the oil passage 74 and connects to the back pressure chamber 67 of the second directional control valve 54. A drain oil passage 82 branches from a middle of the oil passage 78 to the tank 59. Is connected to

The second direction switching valve 54 is a 6-port, 3-position switching type spool valve.
A piston 54a is formed at the other end and is slidably fitted in the back pressure chamber 67. The three output ports on the secondary side of the second directional control valve 54 are provided with an oil passage 72 directly connected to the low-speed hydraulic clutch 15 and a check valve 62 that allows only the flow of pressurized oil into the low-speed hydraulic clutch 15. It is connected to a passage 76 and an oil passage 79 directly connected to the high-speed hydraulic clutch 16. 1 of the second directional control valve 54
The three input ports on the next side are oil passages 71, 74, and 78 described above.
Is connected to

The second direction switching valve 54 has a low-speed position S1 determined by receiving the biasing force of the spring 61, a high-speed position S3 determined by the advancement of a piston 54a described later against the biasing force of the spring 61, and A transition position S2 in the middle of switching from the position S1 to the high-speed position S3;
Connects the oil passage 71 to the oil passage 72, the oil passage 74 to the oil passage 76, and the oil passage 78 to the oil passage 79. The transition position S2 blocks the oil paths 74, 78, and 79, respectively.
The oil passage 71 is simultaneously communicated with the oil passages 72 and 76. At the high speed position S3, the oil passages 71, 72, and 76 communicate with the oil passage 78, and the oil passage 74 communicates with the oil passage 79. At the high-speed position S3, a throttle valve 63 is provided on the way from the oil passage 71 to the oil passage 72. The second directional control valve 54
The back pressure chamber 67 has a throttle valve 91 and a check valve 9 that allows only oil flow in a direction in which oil is drained from the back pressure chamber 67.
0 are connected in parallel and interposed in the pilot oil passage 75. A low pressure relief valve 56 is connected to the secondary side of the delay relief valve 55, and a lubricating oil passage 81 branched from the low pressure relief valve 56 lubricates the low speed hydraulic clutch 15, the high speed hydraulic clutch 16 and the reverse clutch 17.

In such a configuration, when the first directional control valve 53 is switched from the neutral position N shown in FIG. 2 to the low speed position L shown in FIG. 3 by the operating lever 57, the pressure oil from the main oil passage 70 The oil flows to the oil passage 71 via the low speed position L of the first directional control valve 53. Here, the pilot oil passage 75
Communicates with the tank 59 through the oil passage 73, and the second direction switching valve 54 is maintained at the S1 position.
The pressure oil flowing through 1 is sent from the S1 position of the second direction switching valve 54 to the low-speed hydraulic clutch 15 via the oil passage 72, and the low-speed hydraulic clutch 15 is engaged. At this time, FIG.
As shown by a solid line, the operating oil pressure a of the low-speed hydraulic clutch 15 is gradually increased by the action of the delay relief valve 55 as shown by the solid line. At the time t2, the set maximum hydraulic pressure value P2 is reached, and the engagement is complete. This 0 to time t1
Is the acceleration range at the start. At this time, since the pilot oil passage 75 is open to the tank 59, the second directional control valve 54 is maintained at the S1 position, and the high-speed hydraulic clutch 16 is connected to the tank via the oil passages 79, 78, 82. 5
9 and the reverse hydraulic clutch 17 is connected to the tank 59 via the oil passage 80 and the oil passage 73.

In the transitional period when switching from the low speed position L to the high speed side, as shown in FIG.
At the transitional position K of the first directional control valve 53, the oil passage 71, the S1 position of the second directional control valve 54,
Pressure oil continues to be supplied to the low-speed hydraulic clutch 15 via the oil passage 72. Thereafter, even when the first direction switching valve 53 is switched to the high-speed position H, as shown in FIG. 5, the pressure oil from the main oil passage 70 is sent to the oil passage 74, and further, the second direction switching valve 54 From the S1 position to the oil passage 76, the check valve 76 is opened and sent to the low-speed hydraulic clutch 15 to maintain the engagement of the low-speed hydraulic clutch 15. On the other hand, the pressure oil flowing through the oil passage 74 also flows into the pilot oil passage 75, and is gradually sent to the back pressure chamber 67 of the second direction switching valve 54 via the throttle valve 91, and the second direction oil is sent. The piston 54a of the switching valve 54 starts to be pushed.

When the piston 54a is pushed, the second directional control valve 54, as shown in FIG.
Pass through the position. At the S2 position, the non-engagement state of the high-speed hydraulic clutch 16 is maintained, the hydraulic oil in the low-speed hydraulic clutch 15 is stopped by the check valve 62, and the engagement operation state is maintained. Then, since the pressure oil from the oil passage 74 continues to be further sent to the back pressure chamber 67, when the piston 54a reaches the stroke end and the second direction switching valve 54 switches to the S3 position, as shown in FIG. Hydraulic clutch 1
The pressurized oil that has caused the engagement 5 is gradually drained from the oil passage 72 to the tank 59 via the throttle valve 63 at the S3 position and the oil passages 78 and 82. On the other hand, the pressure oil flowing through the oil passage 74 is sent from the S3 position of the second direction switching valve 54 to the oil passage 79 to engage the high-speed hydraulic clutch 16. When the first directional control valve 53 is switched from the low speed position L or the high speed position H to the neutral position N, the pilot oil passage 75 is opened to the tank 59 through the oil passages 74 and 73, so that the second The hydraulic pressure in the back pressure chamber 67 of the switching valve 54 is
6 is opened to be discharged to the tank 59, and the second direction switching valve 54 is quickly returned to the S1 position.

When the first directional control valve 53 is jumped from the neutral position N to the low-speed position L and immediately switched to the high-speed position H at the start, the state shown in FIG. That is, the pressure oil from the main oil passage 70 is supplied to the first directional control valve 53
At the high-speed position H, the oil passage 74, the S1 position of the second direction switching valve 54, the oil passage 76, and the check valve 62, and the oil is sent to the low-speed hydraulic clutch 15 at the same time, from the pilot oil passage 75 via the throttle valve 91. The oil is also sent to the back pressure chamber 67. The pressure oil for the low-speed hydraulic clutch 15 gradually rises by the action of the delay relief valve 55 with the waveform a shown by a solid line in FIG. 13, and the low-speed hydraulic clutch 15 is loosely engaged, so that the machine body starts slowly.

On the other hand, the pressure oil flowing through the oil passage 74 is supplied to the throttle valve 91.
When the hydraulic pressure acting on the piston 54a gradually flows into the back pressure chamber 67 via the valve and rises until the hydraulic pressure against the urging force of the spring 61 rises, the second directional control valve 54 is pushed rightward in the drawing, as shown in FIG. Automatically to the transition position S2 as described above. Here, since the pressure oil supplied into the low-speed hydraulic clutch 15 is held by the check valve 62, the clutch 15 is maintained in the loosely engaged state for a certain period of time (between the time ta and the time tb in FIG. 13).

Further, since the pressure oil from the hydraulic pump 52 continues to flow through the oil passage 74, the flow of oil into the back pressure chamber 67 continues, and the oil pressure rises until the oil pressure exceeds the oil pressure value P1 (FIG. 13). At time tb), the second directional control valve 54 is further pushed rightward on the paper surface, and the piston 54a reaches the stroke end of the back pressure chamber 67, and automatically switches to the high-speed position S3 as shown in FIG. The oil path 74 communicates with the oil path 79, and the pressure oil having the oil pressure value P1 or more is supplied to the high-speed hydraulic clutch 16 with a waveform b shown by a dotted line in FIG. The supplied hydraulic pressure rises to the maximum hydraulic pressure value P2 set by the delay relief valve 55.

As described above, since the high-pressure hydraulic clutch 16 is not supplied with the pressure oil having the predetermined hydraulic pressure value P1 or less, unnecessary slip does not occur in the high-speed hydraulic clutch 16, the energy load thereof is reduced, and the low-speed hydraulic clutch 15 On the other hand, a friction material having a low heat capacity can be used, and it can be manufactured at low cost. Further, in the initial stage in which the high-speed hydraulic clutch 16 is engaged, the pressure oil in the low-speed hydraulic clutch 15 is subjected to the flow rate limiting operation of the throttle valve 63 from the oil path 72 and
8. Since the oil is gradually discharged to the tank 59 through the oil passage 82, the power of the low-speed hydraulic clutch 15 is gradually cut off, and the double power transmission state is actively produced under a relatively low pressure condition. Let me. This region functions to smoothly increase the starting acceleration, and can improve the riding comfort at the time of upshifting.

When the first directional control valve 53 is switched from the high-speed position H to the low-speed position L in order to decelerate (time t8 in FIG. 12), the state shown in FIG. The pressure oil from the oil passage 70 is supplied to the first directional control valve 5.
3 is sent to the oil passage 71 from the transition position K and momentarily passes through the transition position K of the first direction switching valve 53. Here, the pressure oil flowing through the main oil passage 70 is sent from the transition position K to the oil passage 71, is discharged from the oil passage 78 to the tank 59 through the high-speed position S3 of the second directional control valve 54, and has a delay relief. The pressure oil in the control piston of the valve 55 is also discharged to the tank 59 through the oil passage 78, so that the delay relief valve 55 is reset to the initial low pressure P3 setting state. The pressure oil in the high-speed hydraulic clutch 16 passes from the oil passage 79 through the high-speed position S3 of the second directional control valve, and
4 through the transient position K of the first directional control valve 53 and the oil passage 7
3 to the tank 59.

The pressure oil in the back pressure chamber 67 of the second direction switching valve 54 is supplied to the pilot oil passage 7 by opening the check valve 90.
5. The oil path 74 is reached. Here, the throttle valve 100 is interposed in the oil passage connecting the oil passage 74 and the oil passage 73 at the transition position K of the first direction switching valve 53, so that the pressure oil in the high-speed hydraulic clutch 16 Since the fluid is gradually discharged to the tank 59 while being subjected to the flow rate restricting action of the valve 100, the power of the high-speed hydraulic clutch 16 is gradually cut off (from time t8 to t9 in FIG. 12), during which the engine brake operates. The aircraft begins to slowly decelerate. The return of the second directional control valve 54 to the low-speed position S1 is also delayed.

Thereafter, when the first directional control valve 53 is set at the low speed position L shown in FIG. 9, the tank opening state of the control piston of the delay relief valve 55 is blocked. Then, the second direction switching valve 54 is in the transition position S2 shown in FIG.
The pressure oil which is automatically switched to the low-speed position S1 through the oil passage 71 and flows into the oil passage 71 passes through the oil passages 72 and 76,
5 while the oil pressure is being supplied to the delay relief valve 55
12 is gradually increased from the initial set pressure P3 of FIG.
Time t9). The vehicle idles from time t9 to time t10 in FIG. 12, and at the time t10, the low-speed hydraulic clutch 15 starts loosely engaging and the aircraft travels at the set speed of the low-speed hydraulic clutch 15. In other words, a smooth downshift when shifting from high-speed running to low-speed running is obtained.

[0030]

As described above, the present invention has the following advantages. That is, since the first directional control valve 53 is moved from the neutral position N to the high-speed position H at a stretch, the second directional control valve 54 smoothly shifts up from the low-speed hydraulic clutch 15 in order. The aircraft can be accelerated smoothly without impairing the starting feeling. Since this operation is performed by the hydraulically responsive second directional control valve 54 without relying on the conventional electronic control unit, it can be manufactured at low cost and reliability is improved. Further, when the vehicle body is accelerated to some extent by the engagement of the clutch 15 on the low speed side, the hydraulic clutch 16 is switched to the hydraulic clutch 16 on the high speed side, so that unnecessary friction does not occur on the friction plate of the high speed hydraulic clutch 16 and the energy burden is reduced. It is possible to use a friction plate having reduced heat capacity and a lower heat capacity as compared with the hydraulic clutch 15 on the low speed side, so that it can be manufactured at low cost.

Further, since the second directional control valve 54 is switched as described above, the first directional control valve 53 is switched by judging the presence or absence of hydraulic oil output when the first directional control valve 53 is at the high speed position H. As a result, the operation is automatically switched without any operation, and the hydraulic pressure acting on the back pressure chamber 67 is adjusted by the throttle valve 91, so that the sequence operation at the time of shifting up the second direction control valve 54 becomes stable. The operation can be ensured, and the cost can be reduced only by providing the throttle valve 91.

In addition, since the first directional control valve 53 is moved from the neutral position N to the high-speed position H, the hydraulic pressure is supplied from the low-speed hydraulic clutch 15 to the high-speed hydraulic clutch 16 when the first directional control valve 53 is moved from the neutral position N to the high-speed position H. The configuration of the oil passage for switching the direction can be simplified, and the second direction switching valve 54 can be manufactured at low cost.

In addition, since the pressure oil is supplied to the high-speed side hydraulic clutch 16 when the high-pressure side hydraulic clutch 16 starts to be supplied, the low-speed side hydraulic clutch 15 is in a power transmission state under a low pressure condition, and the dual power transmission is performed. The state can be brought out, the acceleration can be smoothly increased, and the riding comfort at the time of upshifting can be improved.

Also, with the configuration as described in claim 5, when the supply of the hydraulic oil to the low-speed side hydraulic clutch 15 starts, the high-speed side hydraulic clutch 16 is in a power transmission state under a low pressure state, and the dual power transmission is performed. The state can be brought out, the deceleration can be smoothly increased, and the riding comfort at the time of downshifting can be improved. Also, by separately providing the flow rate limiting valve 63 for acceleration and the flow rate limiting valve 100 for deceleration, the flow rate can be controlled with respect to the size of the region of the double power transmission state obtained by the flow rate limiting valve 63. The area of the double power transmission state obtained by the restriction valve 100 can be made an ideal size, thereby eliminating unnecessary slip on the friction plate of the hydraulic clutch 15 on the low-speed side and improving its durability. Can be done.

When the first directional control valve 53 is in the neutral position N, the low-speed side hydraulic clutch 15 or the high-speed side hydraulic clutch 16 is instantaneously powered off. Therefore, the aircraft can be stopped naturally.

[Brief description of the drawings]

FIG. 1 is a skeleton diagram of a power transmission system equipped with a hydraulic clutch type transmission.

FIG. 2 is a hydraulic circuit diagram of the hydraulic control device according to the present invention when the first directional control valve is in a neutral position.

FIG. 3 is a hydraulic circuit diagram when the first directional control valve is similarly switched to a low speed position.

FIG. 4 is a hydraulic circuit diagram at a transitional position when the first directional control valve is switched from a low speed position to a high speed position.

FIG. 5 is a hydraulic circuit diagram when the first directional control valve is similarly switched to a high-speed position.

FIG. 6 is a hydraulic circuit diagram in which the first directional control valve is in the high-speed position and the second directional control valve is in the process of switching.

FIG. 7 is a hydraulic circuit diagram showing a state in which the switching of the second directional control valve at the high-speed position of the first directional control valve is completed.

FIG. 8 is a hydraulic circuit diagram at a transition position where the first directional control valve switches from a high-speed position to a low-speed position.

FIG. 9 is a hydraulic circuit diagram showing a state in which the first directional control valve is switched to a low-speed position.

FIG. 10 is a hydraulic circuit diagram in which the first directional control valve is in the low-speed position and the second directional control valve is in the process of switching.

FIG. 11 is a hydraulic circuit diagram showing a state in which the switching of the second directional control valve is completed at the low speed position of the first directional control valve.

FIG. 12 is a diagram showing a relationship between a clutch operating oil pressure and a clutch pressure-up time when the hydraulic clutch transmission is switched from a neutral position to a low speed position, a high speed position, and a low speed position.

FIG. 13 is a diagram showing a relationship between a clutch operating oil pressure and a clutch pressure-up time when the hydraulic clutch type transmission is switched from a neutral position or a low speed position to a high speed position.

[Explanation of symbols]

 15 Low-speed hydraulic clutch 16 High-speed hydraulic clutch 17 Reverse clutch 53 First directional control valve 54 Second directional control valve 57 Shift lever 62 Check valve 75 Pilot oil passage

Claims (6)

[Claims] 1. A hydraulic oil supply / discharge circuit for a plurality of hydraulic clutches 15, 16, 17 in a hydraulic clutch type transmission for changing vehicle speed, the hydraulic oil supply to the hydraulic clutches 15, 16, 17 is selectively performed. A first direction switching valve 53 for switching is provided, and a hydraulic oil supply / discharge circuit portion between the first direction switching valve 53 and a plurality of hydraulic clutches 15 and 16 on the forward side of the hydraulic clutch type transmission is provided with the hydraulic clutch 15. 1
When the first directional control valve 53 is in the high-speed position H, the second directional control valve 54 is moved from the low-speed position S1. A hydraulic control device for a hydraulic clutch type transmission, wherein the hydraulic control device is configured to automatically shift up in a direction of a high speed position S3. 2. The back pressure chamber 67 of the second directional control valve 54.
The hydraulic oil output when the first directional control valve 53 is in the high-speed position H is acted on through the throttle valve 91 so that the second directional control valve 54 is sequentially operated from the low-speed position S1.
2. The hydraulic control device according to claim 1, wherein the hydraulic control device is configured to automatically switch to the high-speed position S3. 3. The hydraulic oil output when the first directional control valve 53 is at the low speed position L, the hydraulic oil supply / discharge circuit portion between the low speed side hydraulic clutch 15 and the second directional control valve 54,
In addition, each of the hydraulic oils output when the hydraulic oil is at the high-speed position H is constituted by two oil passages 72 and 76 that can be independently introduced. The hydraulic control device for a hydraulic clutch-type transmission according to claim 2, further comprising a check valve (62) for permitting only oil flow to the transmission. 4. When the first directional control valve 53 is switched from the low-speed position L to the high-speed position H, the low-speed hydraulic clutch 1
5. The hydraulic control device for a hydraulic clutch type transmission according to claim 1, further comprising a valve 63 for restricting a drain flow rate of the hydraulic motor. 5. A high-speed side hydraulic clutch 1 for switching the first directional control valve 53 from a high-speed position H to a low-speed position L.
The hydraulic control device for a hydraulic clutch-type transmission according to claim 4, wherein a valve (100) for limiting the drain flow rate is provided separately from the valve (63). 6. A check valve 90 which allows only oil flow in a direction in which oil is drained from a back pressure chamber 67 of the second direction switching valve 54 is provided in parallel with the throttle 91, and is provided in the first direction. When the switching valve 53 is switched from the high-speed position H to the neutral position N or from the low-speed position L to the neutral position N, the hydraulic oil of the engaged hydraulic clutches 15 and 16 is drained to the tank instantaneously. 3. The hydraulic control device for a hydraulic clutch type transmission according to claim 2, wherein: