JP2000280771A - Pto device of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PTO device capable of being easily assembled and disassembled for maintenance and capable of being easily connected to a PTO shaft, in a PTO device having a PTO brake for braking the clutch driven side in the disconnected state of a PTO clutch. SOLUTION: A PTO brake 27 is constituted so as to perform braking by the action of oil pressure and so as to release braking by the action of a spring 33. Oil pressure supply/discharge control in relation to the PTO brake is performed by a hydraulic pilot-type directional switching valve 49 to be displaced from the oil supplying position A to the oil discharging position B by the active oil pressure in relation to a PTO clutch 4. An oil supply circuit 50 in relation to the PTO clutch is provided, and it is desirable that the pilot operation of the directional switching valve is performed by oil pressure upstream of a relief valve 53 to be released by relative low oil pressure. Since the directional switching valve is in the oil supplying position in an engine stopped state, but a hydraulic pump 17 is stopped, the PTO brake is not operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulically operated P
The present invention relates to a PTO device of a work vehicle provided with a TO clutch and a PTO brake for braking a clutch driven side in a disengaged state of the PTO clutch.

[0002]

2. Description of the Related Art A PTO device for a working vehicle as described above is conventionally known as disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 10-217785.
The inertial rotation of the PTO shaft after the clutch is disengaged is quickly stopped, and the rotation of the PTO shaft, which may be caused by the drag phenomenon by the oil in the clutch in the disengaged state of the hydraulically operated PTO clutch, is prevented.

Conventionally, as disclosed in the above-mentioned publication, the PTO brake is configured to perform braking by the action of a spring and release the braking by the action of hydraulic pressure on the PTO clutch. The PTO brake performs a braking action in the off state, making it difficult to disassemble and assemble the PTO-based gears and bearings during maintenance, and to connect the PTO shaft.

Accordingly, an object of the present invention is to provide a new PTO device for a work vehicle in which the above-mentioned disadvantages are eliminated with a simple structure.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a PTO device for a working vehicle provided with a hydraulically operated PTO clutch (4) and a PTO brake (27) for braking a clutch driven side in a disengaged state of the PTO clutch. Brake (2
7) is braked by the action of hydraulic pressure and the spring (3
The brake is released by the action of 3).
The directional control valve (49) for controlling the supply and discharge of the hydraulic pressure to the TO brake is configured as a hydraulic pilot-type valve that is displaced from the refueling position (A) to the discharging position (B) by the action hydraulic pressure on the PTO clutch (4). It is characterized by having done.

The directional control valve (49) provided in the PTO device of the present invention is kept at the refueling position (A) when the engine is turned off. In this state, the drive of the hydraulic pump is stopped, so that the PTO is stopped. No hydraulic pressure is supplied to the brake (27), so that the PTO brake is in the brake release state. Therefore, the driven side of the PTO clutch (4) can freely rotate, and disassembly and assembly during maintenance of the PTO gears and bearings can be easily performed, and the connection of the PTO shaft can be easily performed. When the engine is started, hydraulic pressure is immediately supplied to the PTO brake (27) via the direction switching valve (49) at the refueling position (A), and the PTO brake immediately takes a braking state to reliably brake the brake driven side. Nevertheless, when the working oil pressure for the PTO clutch (4) is established in order to engage the PTO clutch (4), the direction switching valve (49) for the PTO brake (27) is moved from the oil supply position (A) to the oil discharge position ( B) is automatically displaced to B), so that when the PTO clutch is in operation, the PTO brake takes the brake release state as required.
Since the directional control valve (49) is of the hydraulic pilot type, a simple structure that does not require any operation is sufficient.

Further, in the present invention, a relief valve (53) which performs a relief operation at a relatively low oil pressure is provided in an oil supply circuit (50) for the PTO clutch (4), and the direction switching valve (49) is replaced with the relief valve. It is proposed that the pilot operation is performed by the hydraulic pressure on the upstream side of. According to this structure, the pilot operation of the directional control valve (49) can be performed within the range of the relief pressure of the relief valve, and therefore, the PTO brake (27)
Can be reliably obtained before the PTO clutch (4) operates.

Other features and advantages of the present invention will be clearly understood from the following description with reference to the accompanying drawings.

[0009]

1 to 3 show a rear end of a tractor. A rear end of a transmission shaft 2 driven by an engine (not shown) is provided on a front wall 1a in a rear housing 1 forming a part of the body. Is supported. A transmission shaft 3 is disposed in the rear housing 1 concentrically with the transmission shaft 2 and connected to the transmission shaft 2 at the front end. The transmission shaft 3 is disposed concentrically with the transmission shaft 3 and is connected to the transmission shaft 3 via a hydraulically operated PTO clutch 4. Transmission shaft 5 and this transmission shaft 5
PTO shaft 6 arranged in parallel with and extending rearward of the fuselage
And a PTO shaft 6 connected to the transmission shaft 5 via a mechanical PTO transmission 7 is provided. Transmission shaft 3,
For supporting the PTO shaft 5 and the PTO shaft 6, a support wall 1b integral with the rear housing 1 and a rear lid 1c for closing the rear end opening of the rear housing 1 are used.

A hydraulic lift case 9 for covering an opening 8 in the top wall of the rear housing 1 is provided on the top wall. The hydraulic lift case 9 is composed of a lift arm shaft 10 rotatably supported and right and left sides thereof. Equipped with left and right lift arms 11 attached to the ends of. The hydraulic lift case 9 is provided with a support plate 12 extending between the rear housing 1 and the lift case 9. The gear 13 fixed on the transmission shaft 3, the gear 14 supported by the support plate 12, and the lift A power take-out mechanism is configured to mesh with a gear 15 supported by the case 9 and to a power take-out shaft 16 to which the gear 15 is fixed. The power take-out shaft 16 drives a hydraulic pump 17 mounted on the front surface of the hydraulic lift case 9.

The PTO clutch 4 only slides one and the other friction elements on a rotating support 18 fixedly installed at the rear end of the transmission shaft 3 and a clutch housing 19 fixedly supported on the front end of the transmission shaft 5. A well-known multi-plate hydraulic clutch is provided which freely supports the piston 21 urged backward by the return spring 20 to move forward by hydraulic action to obtain engagement between the friction elements. The PTO transmission 7 has two gears 22 and 23 fixedly installed on the transmission shaft 5 and two gears 24 and 25 loosely installed on the PTO shaft 6 to mesh with the corresponding gears. PTO shaft 6
The gears 24 and 25 are selectively coupled to the PTO shaft 6 by the displacement of the clutch hardware 26 provided only for sliding on the top,
It is configured to obtain two shift speeds.

As clearly shown in FIG. 3, the PTO clutch 4
Is provided with a PTO brake 27 for braking the driven side of the clutch 4 in the disengaged state. This PT
The O brake 27 has a brake shoe 29 supported on the support plate 12 so as to be rotatable about a fulcrum shaft 28 and facing the clutch housing 19 of the PTO clutch 4. On the free end side of the brake shoe 29, a cylinder portion 30 having an open lower end is formed in the support plate 12, and a piston rod 31a vertically downwardly extending from a piston 31 fitted to the cylinder portion 30 is attached to the brake shoe 29. It is in contact with 29 free ends. An oil chamber 32 is provided in the cylinder portion 30 on the upper surface side of the piston 31. A guide rod 31b attached to the upper surface of the piston 31 and inserted into the hole 30a of the cylinder portion 30 has an upper surface side of the support plate 12, A spring 33 for biasing the piston 31 to move upward is wound. As a result, the brake shoe 29 is
The oil pressure is applied to the clutch housing 19 so as to be pressed against the housing 19 to brake the housing 19, and when the oil pressure in the oil chamber 32 is released, the braking is released by the action of the spring 33. The brake shoe 29
It is urged to move in the opposite direction by the weak spring 34 wound around the fulcrum shaft 28 in the opposite direction to the clutch housing 19, and maintains engagement with the piston rod 31a.

As shown in FIGS. 2 and 3, the clutch hardware 26 of the PTO transmission 7 is slid and displaced by a shift fork 37 which slides on a fork shaft 36. Is provided with a rotatable operation shaft 38 that penetrates the
The shifter 39 attached to the inner end of the shift fork 37 is engaged with the shift fork 37, and the shifter 39 caused by the rotational displacement of the operation shaft 38.
It is supposed that the shift fork 37 is slid by the rotational displacement of the PTO transmission device 7. The interlock mechanism 40
It is provided as follows.

That is, the shifter 39 is provided with an upwardly extending extension 39a, and three lock grooves 39N, 39I, and 39II are formed at the upper end of the extension 39a. Further, the cylinder portion 41 which is slightly inclined downward is provided on the support plate 12.
And a lock pin 42 is fitted into the cylinder portion 41, and the lower end lock portion 42a is fixed to the lock groove 39N, 3.
It faces 9I and 39II. The lock pin 42
It is urged downward by a hydraulic pressure acting on an oil chamber 44 formed between a screw plug 43 screwed to the upper end of the cylinder portion 41 and upward by a spring 45 provided in the cylinder portion 41. Movement is biased. The hydraulic pressure acting on the PTO clutch 4 is applied to the oil chamber 44, whereby the interlock mechanism 40 operates the lock portion 42 a of the lock pin 42 when the PTO clutch 4 in which the oil pressure acts on the oil chamber 44 is engaged.
Engages with any of the lock grooves 39N, 39I, and 39II to prevent the PTO transmission 7 from slipping out of gear. When the PTO clutch 4 is in the disengaged state, the spring 45 causes the shifter 39 by the lock portion 42a of the lock pin 42.
Are released to allow the sliding movement of the clutch hardware 26.

FIG. 4 shows a hydraulic circuit for the PTO clutch 4, the PTO brake 27 and the interlock mechanism 40. The hydraulic pump 17 driven by the engine 47 is used as a hydraulic pump for refueling. The discharge circuit of the hydraulic pump 17 includes a direction switch for controlling supply and discharge of hydraulic pressure to the PTO clutch 4 and the interlock mechanism 40. A valve 48 and a direction switching valve 49 for controlling the supply and discharge of hydraulic pressure to and from the PTO brake 27 are provided in parallel with each other.

The directional control valve 48 is configured as a 4-port, 2-position solenoid valve.
The oil supply circuit 50 is connected directly to the oil chamber 44 of the interlock mechanism 40 and is connected to the oil supply / discharge circuit 52 of the PTO clutch 4.
The oil discharge circuit 51 is connected to an oil supply / discharge circuit 52 via a relief valve 53 which operates at a relatively low oil pressure. The directional control valve 48 includes a neutral position N for draining oil from the oil supply circuit 50 and the oil discharge circuit 51, and a
And an operation position I at which one end is blocked and oil flows out to the oil supply circuit 50. The oil supply / discharge circuit 52 includes a 4-port 2-position control valve 54 having an oil discharge position I and an oil supply position II.
And the oil pressure from the oil discharge position I to the oil supply position I
It is connected to the PTO clutch 4 via a hydraulic pilot type control valve 54 which is displaced to I. A well-known modulated-type relief valve 55 is connected to one port on the output side of the control valve 54, and the relief valve 55 can gradually increase the working oil pressure on the PTO clutch 4.

The directional control valve 49 is provided with an oil supply position A for supplying oil discharged from the hydraulic pump 17 to an oil supply / discharge circuit 56 connected to the PTO brake 27, and an oil discharge position B for draining oil from the oil supply / discharge circuit 56. And a four-port, two-position valve. And this directional control valve 49
The relief valve 5 is configured to be displaced from the oil supply position A to the oil discharge position B by the oil pressure acting on the opposite side of the valve spring 49a, and to perform the relief operation at a relatively low oil pressure.
The oil pressure on the upstream side of 3 is made to act via the pilot circuit 57, and the relief valve 53 is already displaced from the oil supply position A to the oil discharge position B before the relief valve 53 performs the relief operation.

A line filter 60 and a relief valve 61 as a bypass valve are connected in parallel to an oil suction circuit 59 from an oil tank 58 provided at a lower portion in the rear housing 1 to the hydraulic pump 17. Has been inserted.
When the line filter 60 is clogged, the relief valve 61 performs a relief operation to maintain the oil flow to the hydraulic pump 17. A main relief valve 62 and a secondary relief valve 63 for setting a lubricating oil pressure are connected to the discharge circuit of the hydraulic pump 17, and a friction element portion of the PTO clutch 4 is lubricated between the relief valves 62 and 63. A lubricating oil circuit 64 for performing the above operation is derived. The relief oil of the modulation type relief valve 55 is supplied to the lubricating oil circuit 64.
Has been joined to.

The operation of the hydraulic circuit shown in FIG. 4 will now be described.
The oil is drained from the PTO clutch 4 and the interlock mechanism 40 through the directional switching valve 48, and the PTO clutch 4 is turned off and the interlock mechanism 40
Is inactive. The direction switching valve 49 is located at the refueling position A.
But the engine 47 is stopped and the hydraulic pump 17
Is in a stopped state, no oil is supplied to the oil supply / discharge circuit 56, and the PTO brake 27 is turned off.

When the engine 47 is started from this state,
Since the direction switching valve 49 is at the oil supply position A, oil is immediately supplied to the oil supply / discharge circuit 56 and the PTO brake 27 is engaged.

When the direction switching valve 48 is displaced to the operation position I, oil is supplied to the oil supply circuit 50 to operate the interlock mechanism 40 and the oil pressure of the oil supply circuit 50 causes the relief valve 53 to operate before the relief operation. Then, the direction switching valve 49 is displaced to the oil discharge position B via the pilot circuit 57, the oil is drained from the oil supply / discharge circuit 56, and the PTO brake 27 is turned off. Thereafter, the PTO clutch 4 is operated by the relief operation of the relief valve 53 and the automatic displacement of the control valve 54 to the refueling position II.
, The hydraulic pressure is gradually increased, and is gradually engaged.

When the directional control valve 48 is returned to the neutral position N, the control valve 54 is automatically displaced to the oil discharge position I and the oil supply / discharge circuit 5
2 and the oil drain from the PTO clutch 4 via the oil drain circuit 51, the PTO clutch 4 is disengaged,
The interlock mechanism 40 is deactivated by the oil drain from the oil supply circuit 50. Then, since the oil pressure of the oil supply circuit 50 is lost, the direction switching valve 49 is automatically turned to the oil supply position A.
And the PTO brake 27 is engaged.

FIGS. 5 and 6 show the support plate 12. FIG. The support plate 12 is formed in a substantially rectangular shape, and has an appropriate number of knock pin holes 66 and bolt insertion holes 67. As shown in FIG. 1 and FIG.
And is attached to the hydraulic lift case 9 by a bolt 69 that is inserted from the lower surface into the bolt insertion hole 67 and screwed into the screw hole of the hydraulic lift case 9.

The support portion 70 of the gear 14 has a pair of bearing portions 70a and a gear passage hole 70b therebetween as shown in FIG. 5, and a support shaft 14 to which the gear 14 is fixed as shown in FIG.
a is supported by the bearing portion 70a, and the gear 14 is
0b. As shown in FIGS. 5 and 6, the cylinder portion 30 is formed at one corner of the support plate 12. In order to apply a hydraulic pressure to an oil chamber 32 (FIG. 3) in the cylinder portion 30, an upper surface of the support plate 12 is required. The opened port 71 is communicated with the inside of the cylinder portion 30 by an oil passage 72 in the support plate 12. The cylinder portion 41 is formed at another corner, and an oil chamber 44 in the cylinder portion 41 is provided.
In order to apply hydraulic pressure to (FIG. 2), a port 73 opened on the upper surface of the support plate 12 is connected to an oil passage 74 in the support plate 12.
This communicates with the inside of the cylinder portion 41. A hole 75 for fitting and supporting the fulcrum shaft 28 of the brake shoe 29 is also provided.
It is formed on the support plate 12.

As shown in FIG. 1, the hydraulic lift case 9 is integrally formed with an abutment 9a facing forward, and FIG. 4 is described on a valve block 77 installed on the upper surface of the abutment 9a. A direction switching valve 48 is provided. In the valve block 77, the directional control valve 49 and the control valve 54 of the hydraulic pilot type described above with reference to FIG.
55, 62 and 63 are incorporated together with the oil passage therebetween. An oil suction pipe 78 for sucking oil from a lower part in the rear housing 1 is connected to the hydraulic pump 17, and an oil supply pipe 79 is connected between the hydraulic pump 17 and the valve block 77. Although not shown, the interior of the valve block 77 and the ports 71 and 73 of the support plate 12 are connected by an oil passage formed in the support 9a.

As shown in FIG. 1, two pipes 81 and 82 led from a valve block 77 are connected to the rear cover 1c of the rear housing 1. Pipe 81 is P
It supplies and discharges hydraulic oil to and from the TO clutch 4, and is connected to an oil chamber behind the piston 21 of the hydraulic clutch 4 via an oil passage in the rear lid 1c and a hydraulic oil passage 83 in the transmission shaft 5. The pipe 82 supplies lubricating oil, and is supplied through an oil passage in the rear cover 1 c and a lubricating oil passage 84 in the transmission shaft 5.
The friction element portion of the TO clutch 4 and the front end of the transmission shaft 5 are guided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing a part of a tractor equipped with one embodiment of the present invention.

FIG. 2 is a longitudinal sectional side view showing a part of the tractor, taken along a longitudinal section different from FIG. 1;

FIG. 3 is a vertical sectional front view of the tractor.

FIG. 4 is a circuit diagram showing a hydraulic circuit of the embodiment.

FIG. 5 is a plan view showing a support plate provided in the embodiment.

FIG. 6 is a sectional view taken along the line VI-VI in FIG. 5;

[Explanation of symbols]

 Reference Signs List 3 transmission shaft 4 PTO clutch 5 transmission shaft 6 PTO shaft 7 PTO transmission device 17 hydraulic pump 19 clutch housing 27 PTO brake 29 brake shoe 30 cylinder portion 32 oil chamber 33 spring 40 interlock mechanism 48 direction switching valve 49 direction switching valve 50 lubrication Circuit 53 Relief valve 56 Oil supply / drain circuit 57 Pilot circuit

 ────────────────────────────────────────────────── ─── Continued from the front page F term (reference) 2B041 AA01 AB05 EA02 EA23 EA24 3D041 AA15 AA57 AA65 AA68 AB04 AB07 AC01 AC11 AD02 AD12 AD18 AD53 AE16 AE41 3D043 AA06 AB12 BC04 BC09 BC16 BC18 BD05 BF07 A03AA A08A AA33 AA87 BA64 BA70 CA09 CC03 CC33 CC35 CC66 CC76 CD05 CD11 DB29 FA11

Claims (2)

[Claims] 1. A PTO of a work vehicle provided with a hydraulically operated PTO clutch (4) and a PTO brake (27) for braking a clutch driven side in a disengaged state of the PTO clutch.
In the TO device, the PTO brake (27) is configured to perform braking by the action of hydraulic pressure and release the braking by the action of the spring (33), and the direction switching valve (49) for controlling the supply and discharge of the hydraulic pressure to and from the PTO brake. ) Is a hydraulic pilot type valve which is displaced from an oil supply position (A) to an oil discharge position (B) by an action oil pressure applied to the PTO clutch (4). 2. An oil supply circuit (50) for a PTO clutch (4) is provided with a relief valve (53) for performing a relief operation at a relatively low oil pressure, and the direction switching valve (49) is arranged upstream of the relief valve. 2. The PTO device according to claim 1, wherein the PTO device is configured to perform a pilot operation by the hydraulic pressure on the side.