JPH07259978A - Reverse control valve for tractor or the like - Google Patents

Abstract

PURPOSE:To stabilize the control of change-over of a reverse clutch by hydraulic oil in a tractor or the like. CONSTITUTION:Solenoid proportional valves 7, 8 and restrictors 9, 10 are provided in a hydraulic circuit 3 communicated with an actuating cylinder 2 for a forward clutch 1, and a hydraulic circuit 6 communicated with an actuating cylinder 5 for a backward clutch 4, respectively. A damper spool 11 for damping hydraulic pressure, and a towing spool 12 for opening and closing the hydraulic circuit 6 on the backward clutch side with the use of the hydraulic pressure are provided in the vicinity of the solenoid proportional valve 7 in the hydraulic circuit 3 on the forward clutch 1 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse control valve which can be used in a reverser clutch for switching between forward and reverse travel of a tractor.

[0002]

2. Description of the Related Art In a reverse control valve using an electromagnetic proportional pressure reducing valve, a reversal clutch which is an actuator via a secondary pressure of the electromagnetic proportional pressure reducing valve by an electromagnetic solenoid. In the configuration in which the operation cylinders of the
Until the scratch is met, the electromagnetic solenoid current is controlled to rise close to the maximum by the controller in order to raise the meet pressure in a short time against the reaction spring of the reverser scratch. The proportional pressure reducing action of the electromagnetic solenoid of the electromagnetic proportional pressure reducing valve is not balanced, and the primary pressure from the pump port acts on the operating cylinder via the secondary pressure side, and serge pressure is generated at the moment when the reverse clutch is engaged. Generate a shock.

[0003]

According to the present invention, a hydraulic circuit 3 communicating with an operating cylinder 2 of a forward clutch 1 and a hydraulic circuit 6 communicating with an operating cylinder 5 of a reverse clutch 4 are provided.
Electromagnetic proportional valves 7 and 8 and throttles 9 and 10 are provided, respectively, and a damper pool 11 for buffering the hydraulic pressure and a damper pool 11 near the electromagnetic proportional valve 7 and the throttle 9 in the hydraulic circuit 3 on the forward clutch 1 side. The hydraulic circuit 6 on the side of the reverse clutch 4 by hydraulic pressure
A reversing control valve having a check spool 12 for connecting and disconnecting.

[0004]

When the forward clutch 1 and the reverse clutch 4 are disengaged, the electromagnetic proportional pressure reducing valves 7 and 8 are not energized, and the operating cylinders 2 and 5 are both connected to the tank port. There is. When the electromagnetic proportional pressure reducing valve 7 is output, the operation cylinder 2 is operated via the throttle 9 of the hydraulic circuit 3 and the forward clutch 1 is connected. At this time, the hydraulic pressure on the secondary side of the electromagnetic proportional pressure reducing valve 7 is absorbed by the damper pool 11, so that the abrupt hydraulic pressure is relieved and the traction spool 12 is closed, so that the reverse clutch 4 side. The hydraulic pressure to the hydraulic circuit 6 is cut off. Therefore, the reverse clutch 4 is not engaged when the forward clutch 1 is engaged.

When the electromagnetic proportional pressure reducing valve 8 is output, the operating cylinder 5 is operated by the hydraulic pressure that has passed through the throttle 10 of the hydraulic circuit 6, and the reverse clutch 8 is connected. If the electromagnetic proportional pressure reducing valve 7 is output at this time, the operating cylinder 2 on the side of the forward clutch 1 is actuated and the check spool 12 is actuated, and the electromagnetic proportional pressure reducing valve 8 is actuated.
Since the hydraulic pressure to the hydraulic circuit 6 on the side is cut off, only the forward clutch 1 is engaged.

With such a structure, the hydraulic pressure control in the operating cylinders 2 and 5 of the forward and reverse clutches 1 and 4 can be stabilized, and the secondary pressures of the electromagnetic proportional control valve 7 and the throttle 9 can be increased. It can be absorbed by the damper pool 11, and at the same time, the operation of the operation cylinder 5 on the reverse clutch 4 side can be restrained, so that the safe forward and reverse operation with a small impact can be performed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The hydraulic circuit configuration of a tractor will be described with reference to FIGS. The hydraulic pump has a main pump P1 and a sub-pump P2, and a hydraulic circuit 13 on the main pump P1 side performs an elevating control valve 14 by electronic control or an elevating control valve 15 by mechanical operation control, and lowering speed control. Slot
The lift cylinder 17 can be connected through the return valve 16 to control the working machine up and down.

In addition to this, a sub-lift cylinder 1 is provided which is provided with a sub-control valve 18 to elevate and lower other working machines.
9 can be controlled. It is structured such that it is connected to a horizontal cylinder 22 having a horizontal control valve 21 via a diversion valve 20 to perform rolling control of a working machine. The power circuit 25 is connected to the hydraulic circuit 23 by the hydraulic pump P2 via the pressure reducing valve 24.
Connected to the operation cylinders 2 and 5 of the reverser via the reverse control valve 26, linked to the PTO clutch 28 via the switching control valve 27, and full-time 4WD switching via the switching control valve 29. It is configured to interlock with the clutch 30 and interlock with the traveling speed change clutch 32 via the electronic speed change control valve 31.

The details of the reverse control valve 26 are as follows: the pump port P, the tank port T, the cylinder port F of the hydraulic circuit 3 communicating with the operating cylinder 2 for the forward clutch 1, and the reverse clutch 4. Electromagnetic proportional pressure reducing valves 7, 8 and throttles 9, 10 and the like are provided between the cylinder port R of the hydraulic circuit 6 communicating with the operation cylinder 5 and the cylinder ports F of these electromagnetic proportional pressure reducing valves 7, 8. The diaphragms 9 and 10 are provided near the R side, and the diaphragms 9 and 1 are
Damper pools 11, 3 are connected to the hydraulic circuits 3, 6 up to 0.
3 are in communication. Further, in the hydraulic circuit 3 on the side of the forward clutch 1, the damper spool 11 and the restraining spool 12 are provided.
Are in communication. The damper pool 33 on the reverse clutch 4 side may not be provided as shown in FIG.

The check spool 12 is provided in front of the electromagnetic proportional pressure reducing valve 8 of the hydraulic circuit 6 so as to be opened and closed. When the hydraulic pressure on the forward clutch 1 side rises, the hydraulic circuit 6 on the reverse clutch 4 side is opened. When the forward clutch 1 side is neutralized, on the contrary, the hydraulic circuit 6 on the reverse clutch 4 side causes this check spout
It can be opened by opening the rule 12. N is a lubrication port for lubricating the reverser scratch. Reference numerals 34 and 35 are diaphragms. VF and VR are pressure sensors of the cylinder ports F and R, respectively.

The positions of the diaphragms 9 and 10 and the damper pools 11 and 33 are such that the damper pools 11 and 33 communicate with the cylinder ports F and R of the diaphragms 9 and 10 as shown in FIG. It may be configured. The arrangement and configuration of the reverser clutch 36 will be described with reference to FIG. A clutch shaft 38 driven from the engine via the main clutch 37, and an intermediate gear shaft 3 gear-transmitted from the reverser shaft 38.
A reverse shaft 41 and the like are mounted on a clutch housing 42 via 9, 40 and the like, and a forward rotation forward gear 42 is freely rotatable on the front side of the reverse shaft 41 and a reverse gear 43 is freely rotatable on the rear side. And the reverse shaft 41 between the two gears 42 and 43.
And a clutch coupling 44 that rotates integrally with the clutch coupling 44.
6 are provided with pistons 47, 48 which are axially operated by 6 and a wet multi-plate type forward clutch 1 and reverse clutch 4 which are turned on and off by these pistons 47, 48 of each clutch coupling 44 are fitted. The forward and reverse cylinder ports F, R, the lubrication port N, etc. are supplied and discharged through oil passages F1, R1, R1 provided along the reverse shaft 41.

The rear end of the reversing shaft 41 is interlocked with the transmission shaft in the transmission case, and the intermediate gear shaft 39 is connected to the PTO shaft.
It is linked to the transmission shaft. The configuration of each of the electromagnetic proportional pressure reducing valves 7, 8 and the like will be described with reference to FIGS. 5 to 7, and FIG. The spool valves 51 and 52 of the solenoid proportional valves 7 and 8 are fitted and inserted in the valve sleeves 53 and 54 in the same manner in the valve body 50, and solenoids 55 mounted on one side of the valve body 50. 56 actuators 57, 58
By this, switching operation is performed against the spool springs 59, 60 and the like.

Each spool valve 51, 52 is formed with a notch A for opening and closing between an area C communicating with the pump port P and an area D communicating with the cylinder port F or R.
Further, a notch B is formed to open and close between the area D and the area E communicating with the tank port T. These notches A,
The spool diameter and the hydraulic cross-sectional area where B is formed are appropriately set to A <B, and a differential pressure is generated by the oil pressure in the area D to resist the pressing of the actuators 57 and 58.

The operation of the spool valves 51 and 52 is pressed according to the amount of current of the solenoids 55 and 56. This pressing force is the difference between the hydraulic pressure difference in the area D and the tension force by the springs 59 and 60. It resists synthetic power. The movement of the spools 51 and 52 is stopped at these equilibrium positions. When the throttles 9 and 10 of the hydraulic circuit 3 are arranged as shown in FIG. 3, they are arranged between the area D and the check spool 12 as shown in FIG. The location is close. When no current flows through the solenoids 55 and 56, the spool valves 51 and 52 are connected to the cylinder poles.
Both ports F and R communicate with the tank port T, and the pistons 47 and 48 do not operate. At this time, the hydraulic pressure of the pump port P is applied to the area C, but is blocked by the spool having the notch A.

When the solenoid 55 or 56 is energized,
The actuator 57 or 58 presses the spool valves 51 and 52 with a pressure according to the current value. Taking the energization of the solenoid 55 as an example, the hydraulic pressure of the pump port P is limited to the throttles 34, 35.
The oil supplied in accordance with the respective differential pressures of the above and passed through the throttle 34 flows into the area C from the pump ports P of the respective spool valves 51, 52.

When the solenoid 55 is operated, the oil in the area C flows into the area D through the notch A and reaches the set pressure. At this time, the hydraulic pressure in the area D stands on the restraint spool 12, and when a pressure against the pressure spring 61 of the restraint spool 12 is generated, the movement of the restraint spool 12 causes the electromagnetic proportional pressure reduction on the reverse clutch 4 side. Area C of valve 8
The circuit is cut off to restrain the operation of the reverse clutch 4. That is, even if the spool valve 52 on the reverse drive side is energized due to an electrical failure or the like, the oil does not flow into the cylinder port R, so that the hydraulic pressure does not build up in the cylinder port R.

On the contrary, when the solenoid 55 on the forward side is energized while the cylinder port R has been previously fed by the reverse side spool valve 52, the cylinder port R
Immediately, the oil pressure in the cylinder drops and the oil pressure rises in the cylinder port F.
That is, it is configured as a priority circuit of the cylinder port F so that it can move forward even if some trouble occurs.

The movement of the restraining spool 12 at this time also serves as a damper when the forward clutch 1 is engaged, that is, a function of impact force. This is the diameter of the restraining spool 12 and the spring 6
If 1 pressure is set and it is configured to move at a constant pressure,
From the moment the forward clutch 1 meets the solenoid 55
The pressure due to and the reaction force of the spool valve 51 become equilibrium, and until the normal oil pressure is reached, the restraining spool 51 moves, and an oil flow is generated from the volume of this moving amount. This is because the instantaneous surge pressure is absorbed.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a reverse control valve unit.

FIG. 2 is a hydraulic circuit diagram of a tractor.

FIG. 3 is a hydraulic circuit diagram showing an embodiment of a part thereof.

FIG. 4 is a side view of a reverser clutch portion.

FIG. 5 is an enlarged plan view of a reverse control valve portion.

FIG. 6 is a side view thereof.

FIG. 7 is a front view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Forward clutch 2 Operation cylinder 3 Hydraulic circuit 4 Reverse clutch 5 Operation cylinder 6 Hydraulic circuit 7 Electromagnetic proportional pressure reducing valve 8 Electromagnetic proportional pressure reducing valve 9 Throttle 10 Throttle 11 Damper spool 12 Checking spool

Claims (1)

[Claims] 1. A hydraulic circuit 3 communicating with an operating cylinder 2 of a forward clutch 1 and a hydraulic circuit 6 communicating with an operating cylinder 5 of a reverse clutch 4 are provided with electromagnetic proportional valves 7, 8 and throttles 9, 10, respectively. The hydraulic circuit 3 on the forward clutch 1 side is provided.
In the vicinity of the solenoid proportional valve 7 and the throttle 9 in FIG. 2, a damper spool 11 for buffering this hydraulic pressure, and a check spool 12 for connecting and disconnecting the hydraulic circuit 6 on the reverse clutch 4 side with this hydraulic pressure.
Reverse control valve provided with.