JPH088355Y2 - Control device for hydraulic clutch of vehicle - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention makes it possible to perform a slip operation and a slip operation of the hydraulic clutch by depressurizing the hydraulic pressure acting on the hydraulic clutch inserted in the traveling power transmission path to a variable degree of decompression. An operation control device for a hydraulic clutch for a vehicle, which is provided with an inching valve, in which the main clutch for continuing transmission of traveling power is unnecessary and the engine is started to start the vehicle by using the inching valve. The present invention provides a novel clutch actuation control device for safety.

[Conventional technology]

It is well known that an inching valve as described above is provided in a vehicle for various works such as agricultural work and civil engineering work (see, for example, Japanese Utility Model Laid-Open No. 59-136070), and an inching valve that is generally pressure-reduced by a pedal is used. As a result, a variable low vehicle speed that is lower than the steady vehicle speed when the normal high hydraulic pressure is applied to the hydraulic clutch can be obtained according to the work purpose.

In vehicles equipped with hydraulic clutches or other types of clutches that can selectively cut off the traveling power transmission path, it is also possible to start the engine only when the clutch is in the cut state for safety. (See, for example, Japanese Utility Model Laid-Open No. 53-145040), such a vehicle is often provided with a sensor switch for electrically detecting the clutch cut state, which is inserted in the starting circuit of the engine.

[Problems to be solved by the invention]

As described above, regarding a vehicle in which the engine can be started only in the clutch-off state, when the gearshift lever is moved to the operating position in advance and the vehicle is started at the same time as the engine is started, the clutch pedal is fully depressed. It is safe because the vehicle will start after passing through the semi-clutch state by gradually depressing the pedal from the standing state. However, when the engine is started with the shift lever set to neutral, there are cases where the shift lever is moved to the operating position and the vehicle is started without stepping on the clutch pedal. After starting the engine, it tends to happen when you leave the cockpit. In this case, the vehicle suddenly starts and is dangerous.

Therefore, the present invention has a simple structure using the inching valve as described above to ensure reliable safety when the engine is started and the vehicle is started. In addition, the safety mechanism of the main clutch and the engine starting circuit side is also provided. It is an object of the present invention to provide a new actuation control device for a hydraulic clutch for a vehicle that eliminates the need for and.

[Means for Solving Problems] Therefore, as shown in FIGS. 1 and 4, the present invention is designed so that the hydraulic pressure applied to the hydraulic clutches 1F and 1R, which are displaced by the pedal 11 and inserted into the traveling power transmission path, is used. In an operation control device for a hydraulic clutch for a vehicle, which is provided with an inching valve 2 that depressurizes the hydraulic clutch so that the hydraulic clutches 1F, 1R can perform a slip operation.
Is configured to drain the hydraulic pressure when the displacement operation in the depressurizing direction is maximized, and the oil passage cut-off position I and the oil passage 3 for shutting off the oil passage 3 guided to the primary side of the inching valve 2. The oil passage opening / closing valve 4 having an oil passage opening position II for opening the oil passage is provided, and the depressurization of the inching valve 2 by the spring 5 and the pedal 11 for urging the oil passage opening / closing valve 4 to displace the oil passage opening / closing valve 4 in the oil passage shutoff position I direction. A pressing member 6 that displaces to the oil passage opening position II in association with the operation is provided, and the oil pressure of the oil passage 3 is applied to the oil passage opening / closing valve 4 from the opposite side to the biasing direction of the spring 5. The hydraulic oil passage 7 for holding the oil passage opening / closing valve 4 at the oil passage open position II is
The oil passage opening / closing valve 4 is arranged so as to be shut off at the oil passage shut-off position I of the opening / closing valve 4 and opened at the oil passage open position II.

[Action]

As can be seen from FIGS. 1 and 4, even when pressure oil is supplied to the oil passage 3 by the hydraulic pump 10, the oil passage opening / closing valve 4 is not opened as it is and the biasing force of the spring 5 causes the oil passage shutoff position. I
Be locked in.

When the inching valve 2 is depressurized by the pedal 11, the oil passage opening / closing valve 4 opens the oil passage 3 by the pressing member 6 in conjunction with the depressurization operation. Moved to position II). Therefore, as shown by the arrow in FIG. 11, oil is supplied from the oil passage 3 to the inching valve 2, but since the valve 2 is depressurized, only low oil pressure is established in the oil passage 3, Further, when the pedal 11 is fully depressed and the hydraulic pressure is drained by the inching valve 2, the hydraulic pressure is not established in the oil passage 3. By moving the oil passage opening / closing valve 4 to the oil passage opening position II, the hydraulic oil passage 7 is also opened, and a state in which the oil pressure of the oil passage 3 can act on the oil passage opening / closing valve 4 is obtained.

When the depressurizing operation of the inching valve 2 is released from this state, the pressing member 6 is moved to a position away from the valve 2 as shown in FIG.
Due to the hydraulic pressure established in the oil passage 3 when the decompression is released by the oil passage opening / closing valve 4 similarly, as shown in FIG.
After that, as long as the oil pressure is established in the oil passage 3, it is held at the same position II. By gradually releasing the decompression operation of the inching valve 2, the hydraulic pressure in the oil passage 3, and thus the hydraulic pressure acting on the hydraulic clutches 1F, 1R, is gradually increased,
The hydraulic clutches 1F and 1R can be engaged through the slip state.

When the drive of the hydraulic pump 10 is stopped and the oil pressure is not supplied to the oil passage 3, the oil passage opening / closing valve 4 is urged by the spring 5 to
The oil passage open position shown in FIG. 12 is returned to the oil passage closed position shown in FIG.

[Effect of device]

According to the device of the present invention which operates as described above, even if the engine 12 illustrated in FIG. 4 is started and the drive state of the hydraulic pump 10 is obtained, the oil passage opening / closing valve 4 alone causes the oil passage shutoff valve 4 of FIG. Even if the gear shift lever is placed in the operating position because the hydraulic pressure is not supplied to the hydraulic clutches 1F and 1R because it is held in the position, the stopped state of the vehicle continues. In order to start the vehicle after starting the engine 12, if the gear shift lever is neutral, move it to the operating position and then depress the pedal 11 to depressurize the inching valve 2 and operate as shown in FIG. Hydraulic clutch 1F, 1 unless the condition is obtained and the oil passage 3 is once opened.
Since the hydraulic pressure cannot be supplied to R, the depressurizing action of the inching valve 2 by the pedal 11 is essential. By gradually releasing pedal 11 from that state, hydraulic clutch 1F, 1
The vehicle gradually starts by gradually engaging R.

That is, according to the present invention, when the engine is started and the vehicle is started, the depressurizing operation of the inching valve 2 by the pedal 11 is indispensable. For example, after the operator starts the engine and returns from the cockpit in the state of gear shift neutral. , The vehicle does not start even if the driver forgets to step on the pedal 11 and operates only the gear shift lever.Therefore, the driver notices that the pedal 11 has been forgotten to step on the pedal and starts the vehicle. The safety is ensured by the fact that it is started to the. Since the inching valve 2 drains the hydraulic pressure with the maximum decompression operation,
High safety can be secured by gradually starting the vehicle from a certain stopped state.

This invention provides such a safety by providing an oil passage opening / closing valve 4 having a simple function of simultaneously opening and closing two kinds of oil passages 3 and 7 by using the inching valve 2 and setting the opening / closing valve 4 at the oil passage opening position.
This is achieved by a simple structure of a self-holding type in which the hydraulic action oil passage 7 which is opened by the valve 4 itself when being moved to II is held in the oil passage opening position II. Further, since the traveling power transmission path is cut off by the hydraulic clutches 1F, 1R by the maximum depressurization operation of the inching valve 2, it is not necessary to provide the main clutch. Furthermore, even if the engine is started and the hydraulic pump is driven, the vehicle cannot be started as it is, so there is no need to provide a safety mechanism in the engine starting circuit.

〔Example〕

The embodiment shown in the drawings relates to an example in which the present invention is applied to a tractor, and FIG. 2 shows a front housing 14 constituting a front part of a body of the tractor and a front end portion of a mesh case 15 following the front housing. FIG. 3 illustrates a state in which the rear wall 14a of the front housing 14 is vertically cut.

Inside the front housing 14, there are provided a drive shaft 16 driven by an engine 12 (Fig. 4) and a clutch shaft 17 of a traveling system parallel to the drive shaft 16. The hydraulic clutches 1F, 1R
Are installed on the clutch shaft 17 as two forward and backward clutches for selectively driving the clutch shaft 17 to rotate in the forward direction and the reverse direction of the vehicle by the drive shaft 16. The clutch shaft 17 is connected by gears 18 and 19 to a hollow output shaft 20 arranged concentrically with the driving shaft 16 and provided behind the driving shaft 16. The output shaft 20 is spline-connected to the hollow input shaft 21 of the traveling system of the mesh case 15. The drive shaft 16 is connected to a PTO system input shaft 22 of the transmission case 15 by a coupling 23. In the mesh case 15, between the hollow input shaft 21 and the transmission shaft 24 parallel to the hollow input shaft 21, the second
A traveling transmission 25, a portion of which is shown in the figure, is installed. The input shaft 22 of the PTO system transmits power to a PTO shaft (not shown) extending rearward from the tractor body via a PTO system hydraulic clutch (not shown) and a PTO system transmission.

The forward / reverse switching mechanism including the hydraulic clutches 1F and 1R will be described. Two gears 27 and 28 fixedly installed on the driving shaft 16 at intervals and the clutch shaft 17 are loosely fitted and installed on the clutch shaft 17. The two gears 29 and 30 are meshed directly with each other, and the gears 28 and 30 are meshed with each other through an idler gear (not shown). The clutch housing 31, which is common to both hydraulic clutches 1F and 1R, connects the gear shafts 29 and 30 with the clutch shaft 17.
It is fixedly installed on the top, and each hydraulic clutch 1F, 1R has a gear 29, 30
And a clutch housing (31), which is a friction multi-plate type in which friction elements addressed to a plurality of plates are slidably supported. Piston 32F, 32R of each hydraulic clutch 1F, 1R
In order to displace the clutch spring against the biasing force of the return springs 33F, 33R and obtain clutch engagement, the differential oil passages 34F, 34R drilled in the clutch shaft 17 are connected to the hydraulic chambers 35F, 35R of the hydraulic clutches 1F, 1R. It is in communication with. Lubricating oil passage 34L ₁ are communicated to the bearing portion of the shaft 17 to the clutch shaft 17, and the hydraulic clutch 1F, lubricating oil passage 34L ₂ which are communicated to the friction element of the 1R also there are bored . The above oil passage in the clutch shaft 17
34F, 34R, 34L ₁ and 34L ₂ are opened to an annular groove 36F, 36R, 36L _{2 on the} outer peripheral surface of the rear end of the clutch shaft 17 and an oil chamber 36L _{1 at the} rear end of the clutch shaft 17. The rear wall 14a of the front housing 14 is formed with a thick bearing portion 14b protruding forward, and the annular groove 36F, 36R, 36L ₂ is formed on the inner surface of the hole of the bearing portion 14b.
The oil chamber 36L ₁ is sealed to form a rotary joint portion of the oil passage.

The drive shaft 16, the clutch shaft 17, and the output shaft 20 in the front housing 14 are the support wall portion 14 on the inner surface of the front housing 14.
It is provided so as to be supported by the bearing plate 38 attached to c and the bearing portion 14b. In order to support the front ends of the input shafts 21 and 22 and the transmission shaft 24 in the transmission case 15, a bearing plate 39, which is outlined in broken lines in FIG. 3, is attached to the rear surface of the front housing rear wall 14a by a bolt 40. I have installed it. An oil passage, which will be described later, is formed between the rear wall 14a and the bearing plate 39. First
In FIGS. 2 and 3, reference numeral 41 designates a rear wall 14a so that the lower part of the front housing 14 and the lower part of the case 15 communicate with each other.
It is an oil passage hole formed in.

The outline of the hydraulic circuit provided in the illustrated tractor will be explained with reference to FIG. 4. The input shaft 22 (P.
2, 3) The hydraulic pump 10 driven by the engine 12 is provided through the drawings. The hydraulic pump 10 includes both the hydraulic clutches 1F and 1R and the PTO hydraulic clutch (not shown) that was touched above. It is supposed to supply hydraulic oil to. For that purpose, a shunt valve 43 is provided in connection with the pump discharge circuit, and the adjusted flow discharge circuit of the shunt valve 43, which is a constant flow rate type flow control valve, is a differential oil circuit 44 for the PTO hydraulic clutch. The surplus flow discharge circuit is connected to the hydraulic clutch 1F, 1R differential oil passage 45.
There is. The oil passage 45 is also connected to a diversion valve 46 which is configured as a constant flow rate type flow control valve, and the diversion valve 46 in which the orifice 46a is inserted is used as the oil passage 3 and the oil flow passage 3 is used as the oil passage 3. It is connected to the inching valve 2 via the passage opening / closing valve 4. Relief valve 46 in shunt valve 46
The excess flow discharge circuit in which b is inserted is configured in a hydraulic oil passage 48 for supplying hydraulic oil to the front wheel drive hydraulic clutch 47 provided in the illustrated tractor.

The inching valve 2 has a non-depressurized position A, a depressurized position B, and a hydraulic drain position C, as will be described later in detail, and a bearing to which lubricating oil is supplied through the lubricating oil passages 34L ₁ and 34L ₂ . The supply of lubricating oil to the portion L ₁ and the friction element portion L ₂ is also controlled. The clutch port of the inching valve 2 is connected to the hydraulic clutches 1F and 1R via the direction switching valve 50. Direction switching valve 50
Is provided with a forward drive position F for operating the hydraulic clutch 1F and a reverse drive position R for operating the hydraulic clutch 1R, and the hydraulic pressures of the connecting oil passages 51F, 51R between the switching valve 50 and the hydraulic clutches 1F, 1R are of different hydraulic type. It is supposed to be set by the relief valves 52F and 52R. Lubricating oil passage 53 for supplying the relief oil of both the relief valves 52F and 52R to the primary side of the inching valve 2.
And a low pressure relief valve 54 for setting the oil pressure of the oil passage 53.

Front housing as shown in Figures 2, 3 and 5, 6
An opening 56 is formed in the top wall of 14, and a valve case 59 is attached by a bolt 60 to the inner surface of a lid 58 attached to the top wall of the housing 14 by a bolt 57. As shown in FIGS. 1 and 6, in the valve case 59, the directional valve 50, the inching valve 2, the oil passage opening / closing valve 4 and the diversion valve 46 shown in FIG. 4 are arranged in this order from the front to the rear. It is placed over and arranged along the left-right direction.

As shown in FIGS. 3 and 6, the hydraulic oil passage 45 shown in FIG. 4 extends from one side wall of the movement case 15 to the rear wall 14a of the front housing, and between the rear wall 14a and the oil receiving plate 39. And is communicated with the oil passage 61P in the lid 58 through the rear wall 14a again.As shown in FIGS. 5 and 6, the oil passage 61P is not connected to the pump port 62P of the valve case 59. is there. As shown in FIG. 5, in addition to the pump port 62P, the forward clutch port 62F, the reverse clutch port 62R, and the two lubricating oil ports 62L ₁ and 62L ₂ are opened on the mating surface with the lid 58 in the valve case 59, respectively. Is formed. These ports 62F, 62R, 62L ₁ , 62L
₂ is an oil passage 61F, 61R, 61 inside the lid 58 similar to the pump port 62P.
It is connected to L ₁ and 61L ₂ . The latter oil passage 61F, 61R, 61L ₁ , 61
L ₂ is an oil passage 63F, 63R, 63L extending in the rear wall 14a of the front housing and between the rear wall 14a and the bearing plate 39 as shown in FIG.
₁ , 63L _{2 connecting} to the oil passage in the oil receiving portion 14b of the rear wall 14a
64F, 64R, through 64L _1, 64L _2, are guided to the end position of the oil passage 63L _2, 64L ₂ clutch shaft 17 as shown for.

Explaining the specific structure of the valves provided in the valve case 59, the flow dividing valve 46 connects the pump port 62P to the oil passage opening / closing valve 4 as shown in FIG. The relief valve 46b is slidably fitted and provided in the constituent valve hole. The orifice 46a is provided on a partition wall formed in the middle of the hollow relief valve 46a. The front wheel drive hydraulic clutch 47 (fourth
(Fig.) Connect the front clutch port 62C to the relief valve 4
6b is formed in the valve case 59 so as to face the outer peripheral surface in the middle, and the relief valve 46b shuts off the communication between the oil passage hole 66 formed on the primary side of the orifice 46a in the valve 46b and the front wheel clutch port 62C. The slide spring is biased in the direction by the valve spring 67. The relief valve 46b also has an oil passage hole 68 which constitutes a part of the oil passage 3 and an oil passage hole 69 which allows the oil passage 4 and the hydraulic oil passage 7 to communicate with each other on the primary side of the orifice 46a. Has been formed.

The oil passage opening / closing valve 4 is at the oil passage shut-off position shown in FIG.
Has a land 4a for shutting off the oil passage 7 and a land 4b for shutting off the hydraulic oil passage 7. In the oil passage open position shown in FIGS. 11 and 12, the lands 4a, 4b respectively connect the oil passage 3 and the hydraulic oil passage 7 respectively. It is supposed to be displaced to the open position. The spring 5 is made to act on the oil passage opening / closing valve 4 on the inner end surface of the hollow hole on the side of the land 4a, and the pressing member 6 is formed as a push pin so that the valve case 59 is formed on the opposite side of the spring 5.
It is slidably provided so as to straddle the inside and outside.

Similarly, as shown in FIG. 1, the inching valve 2 is a valve hole that crosses the working oil passage 71 connecting the oil passage opening / closing valve 4 and the direction switching valve 50 back and forth. The lubricating oil ports 62L ₁ and 62L ₂ are opened on one side and the other side, and the end on the lubricating oil port 62L ₁ side is slidable in the valve hole formed in the tank port 62T opening in the front housing 14. It is provided by fitting. This inching valve 2 has a tenth
As shown in the figure, when it is pushed backward by an appropriate amount, the land 2a that variably throttles the hydraulic oil passage 71 at the tapered end to reduce the clutch working hydraulic pressure, and the hydraulic oil passage 71 on the primary side of the inching valve 2 a land 2b which allows intermittently between lubricant port 62L _1, an oil passage hole 2c for communicating the lubricating oil ports 62L ₁ to lubricant port 62L _2, the hydraulic fluid passage 71 of the inching valve 2 secondary Oil passage hole 2d for communicating with oil passage hole 2c
And are provided. Lubricating oil port
As shown in FIGS. 6 and 8, 62L ₁ is configured so that the relief oil passage 72 of the relief valves 52F and 52R installed in the lower portion of the valve case 59 is raised to the upper end surface position of the valve case 59. Has been formed.

The lands 2a, 2b and the oil passage hole 2 of the inching valve 2 described above.
The c and 2d are arranged in the following arrangement. In the inching valve 2, the positions shown in FIGS. 1 and 12 are the non-depressurized position A described above with reference to FIG. 4, the position shown in FIG. 10 is the depressurized position B, and the position shown in FIG. 11 is the hydraulic drain position C. Correspond. The first with the non-reducing position A as land 2a shown in the 1,12 figure decompression large open clutch acting hydraulic working oil passage 71 is not performed, the lubricating oil port 62L _1, lubrication oil is Aburaroana 2c Relief oil from both relief valves 52F and 52R communicates with port 62L _{2 and} both lubrication oil ports 62L ₁ and 62L ₂
It is supposed to be leaked from. Next, at the decompression position B,
As shown in Figure 10, which is the other of the operating oil passage 71 as described above is narrowed in the variable by the land 2a, the communicating area between Aburaroana 2c and lubricant port 62L ₂ is narrowed down to a variable. Further, at the hydraulic drain position C in which the inching valve 2 is pushed backward as much as possible, as shown in FIG. 11, the part of the hydraulic oil passage 71 on the primary side of the inching valve is blocked by the land 2a with respect to the part on the secondary side. At the same time, it is made to communicate with the lubricating oil port 62L ₁ by the escape of the land 2b, and the above-mentioned secondary side portion of the oil passage 71 is communicated with the tank port 62T through the oil passage holes 2b and 2c, and the drain of the clutch action hydraulic pressure. It is said that the oil does not flow out to the lubricating oil port 62L _{2 due} to the disconnection of the communication between the oil passage hole 2c and the lubricating oil port 62L ₂ .

The pedal for depressurizing the inching valve 2
As shown in FIG. 9, 11 is an operating shaft 77 which is projected above the lid 58 through a rod 74, a bell crank 75, and a rod 76.
Is connected to the arm 78 attached to the. An arm 79 is attached to the operation shaft 77 inside the lid 58 as shown in FIGS. 1 and 5, and the operating pin 80 attached to the other end of the arm 79 is used to connect the end of the inching valve 2 and the pressing member (pusher pin) 6. When the pedal 11 is stepped on by engaging the operating plate 81 which is provided so as to bridge the inching valve 2 and the pressing member 6, the inching valve 2 and the pressing member 6 are integrally pushed into the valve case 59 as shown in FIG. It is said that. When the depression of the pedal 75 is released, the inching valve 2 and the pressing member 6 are also returned to the original position by the return spring 82 attached to the pedal 75, as shown in FIG.

As shown in FIG. 1, the directional control valve 50 is provided by a spool fitted in a valve hole formed by opening a forward clutch port 62F and a reverse clutch port 62R at an interval in the left-right direction. The hydraulic oil passage 71 and the ports 62F, 62
Lands 50a and 50b that selectively block between R are switching valves.
It is provided in 50. The direction switching valve 50 is projected to the outside of the valve case 59 on the side opposite to the inching valve 2, and an arm 85 attached to a vertical operation shaft 84 is engaged. The operating shaft 84 projects above the lid 58 as shown in FIG. 9, and the operating rod is provided with universal joints at both ends by a forward / reverse switching lever 86.
The directional switching valve 50 is displaced between the forward drive position F and the reverse drive position R shown in FIG. As shown in FIG. 9, the switching lever 86 is arranged near the sterling wheel 88 of the illustrated tractor. As shown in FIG. 7, the directional control valve 50 is additionally provided with a detent means 89 for obtaining position restraint at each position F, R.

As shown in FIGS. 7 and 8, both the hydraulic pressure gradually increasing type relief valves 52F and 52R are arranged in the lower portion of the valve case 59 along the front-rear direction. On the front side of the relief valves 52F, 52R, oil passages 90F, 9 communicating with the forward and reverse clutch ports 62F, 62R.
Leading 0R. The valve springs 91F, 91R of the relief valves 52F, 52R have their base ends received by the control pistons 93F, 93R, which can move forward to the position where they contact the stopper steps 92F, 92R on the circumferential surface of the valve hole, and behind them. The oil chambers 94F and 94R are formed. A plate 59a, which forms oil passages 95F and 95R for communicating the oil passages 90F and 90R with the oil chambers 94F and 94R, is attached to the lower surface of the valve case 59. As shown in Fig. 4, throttles 96F, 96R are inserted at the ends of the oil passages 95F, 95R. The operation of both relief valves 52F and 52R is well known.

The action obtained by the combination of the inching valve 2 and the oil passage opening / closing valve 4 in the illustrated tractor is as described above as the action of the invention. Even if the engine is started in a neutral state of the transmission 25 of the traveling system, a part of which is shown in FIG.
Even if the engine is started in the operating state of, the vehicle does not start, and the pedal 11 must be operated to start the vehicle.

By moving the inching valve 2 to the depressurization position B by depressing the pedal 11 shallowly in any position of the direction switching valve 50 in the positions F and R, the vehicle can be driven at an adjustable low speed. As described above, the inching valve 2 shown in the drawing restricts the amount of lubricating oil supplied to the friction element portion 34L ₂ of the hydraulic clutches 1F, 1R at the depressurized position B to reduce the effect of lubricating oil on the clutch slip operation. Further, by cutting off the supply of the lubricating oil to the friction element portion 34L ₂ at the hydraulic drain position C, the rotation of the friction elements due to the lubricating oil is eliminated, and the desired stop state of the vehicle is reliably maintained. It In the hydraulic drain position C, the lubricating oil is not supplied from the lubricating oil passage 53 from the relief valves 52F and 52R.
Since the pump discharge oil is supplied to the bearing portion 34L ₁ at the same position C, there is no problem in lubrication of the bearing portion 34L ₁ .

Needless to say, the present invention can be applied to a vehicle having a single hydraulic clutch provided in the traveling power transmission path unlike the case shown in the figure.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view showing a main part of one embodiment of the present invention (a cross section is taken along the line I-I of FIG. 6), and FIG. 2 is a vertical sectional side view showing a part of a tractor equipped with the embodiment. , Fig. 3 is the second
Fig. 4 is a vertical sectional front view substantially along the line III-III in Fig. 4, Fig. 4 is a circuit diagram showing the main part of the hydraulic circuit provided in the tractor, and Fig. 5 is an enlargement along the line V-V in Fig. 2. Sectional drawing, FIG. 6 is an enlarged sectional view along substantially line VI-VI in FIG. 5, FIG. 7 is a sectional view along substantially line VII-VII in FIG. 6, and FIG. A sectional view along the line VIII-VIII, FIG. 9 is a schematic perspective view showing a part of the tractor, FIG. 10 is a cross-sectional plan view showing a part of FIG. 1 in a different state, FIG. 11 and FIG. 12 is a cross-sectional plan view similar to FIG. 1 for explaining the operation. 1F, 1R ... hydraulic clutch, 2 ... inching valve, 2c, 2d ...
Oil passage hole, 3 ... Oil passage, 4 ... Oil passage opening / closing valve, 4a, 4b ... Land,
5 ... Spring, 6 ... Pressing member, 7 ... Hydraulic oil passage, 11
... Pedal, 12 ... Engine, 16 ... Driving shaft, 17 ... Clutch shaft, 20 ... Output shaft, 46 ... Dividing valve, 50 ... Direction switching valve, 59 ... Valve case, 62P ... Pump port, 62F ... Forward clutch port, 62R … Reverse clutch port, 62T… Tank port,
71 ... hydraulic oil passage, 77 ... operating shaft, 79 ... arm, 80 ... operating pin, 81 ... operating plate.

Claims (1)

[Scope of utility model registration request] 1. An inching valve capable of performing a slip operation by variably depressing a hydraulic pressure acting on a hydraulic clutch 1F, 1R inserted into a traveling power transmission path by a pedal 11 so that the hydraulic clutch 1F, 1R can be depressurized. 2 is provided,
In an operation control device for a hydraulic clutch for a vehicle, the inching valve 2 is configured to drain hydraulic pressure when the displacement operation is performed in the depressurizing direction to the maximum, and an oil passage introduced to the primary side of the inching valve 2 An oil passage opening / closing valve 4 having an oil passage opening position for opening the oil passage 3 and an oil passage opening position for opening the oil passage 3 is provided, and a spring for urging the oil passage opening / closing valve 4 to be displaced toward the oil passage opening position. 5 and a pressing member 6 for displacing the inching valve 2 with the pedal 11 in conjunction with the depressurizing operation of the inching valve 2 to the oil passage open position, the oil pressure of the oil passage 3 is changed from the opposite side to the biasing direction of the spring 5. A hydraulic working oil passage 7 for acting on the passage opening / closing valve 4 to hold the oil passage opening / closing valve 4 at the oil passage open position is provided by the hydraulic passage oil opening 7 by the oil passage opening / closing valve 4. The above oil passage shutoff position Operation controller comprising as characterized by providing by arranging so as to be opened in the oil path open position.