JP2802627B2 - Hydraulic control device for dump - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for a dump truck for raising and lowering a carrier.

(Prior Art) In the conventional apparatus shown in FIG. 5, a loading platform 2 is rotatably mounted on a chassis 1 with a hinge 3, and a hydraulic cylinder 4 is provided on the chassis 1. A link mechanism 6 is connected to the tip of the rod 5 of the hydraulic cylinder 4, and the loading platform 2 is moved up and down using the expansion and contraction force of the hydraulic cylinder 4.

A special pressure oil supply source is connected to the hydraulic cylinder 4 as described above, and the hydraulic cylinder 4 uses the pressure oil of the pressure oil supply source.
To drive.

Reference numeral 7 in the figure denotes a stopper provided on the chassis 1, which receives the rotating tip of the carrier 2.

(Problems to be Solved by the Present Invention) In the conventional device as described above, the hydraulic cylinder 4 is located at a position away from the hinge 3 and the link mechanism 6 is moved in order to largely rotate the carrier 2. Therefore, there is a problem that the mounting space is inevitably increased.

In addition, since a special pump is used to drive the hydraulic cylinder 4, there is also a problem that the overall cost increases.

An object of the present invention is to provide a device capable of sufficiently maintaining a dump angle of a carrier even if a mounting space is small.

(Means for Solving the Problems) The present invention provides a pressure oil supply source, a steering control valve connected to the pressure oil supply source, a power cylinder connected downstream of the steering control valve, A switching valve connected to the upstream side of the valve and communicating the steering control valve and the pressure oil supply when neutral, a torque actuator connected to the switching valve, and a reciprocating motion of a piston of the torque actuator. And a rotating mechanism that raises and lowers the dump bed by this rotational force.The torque actuator is formed in both sides of the chamber divided by a piston provided in a housing, and the two chambers are formed in the axial direction of the piston. And a communication between the two chambers due to a pressure difference between the two chambers. Consists of a ball valve that blocks the ball with a ball, and a rod that is fixed to the ball of the ball valve and protrudes from the through hole into both chambers.
When the tip of the rod hits the wall surface of the housing, the ball valve becomes neutral, and both chambers communicate through the through hole, while the switching valve, when it is in the switching position, connects the pressure oil supply source and the torque actuator. It is characterized in that one of the chambers is connected and the other control chamber is connected to the steering control valve.

(Operation of the Present Invention) Since the present invention is configured as described above, the power cylinder and the torque actuator can share the pressure oil supply source. When the switching valve is held at the neutral position, all the pressure oil from the pressure oil supply source is supplied to the power cylinder. When the switching valve is switched, the pressure oil from the pressure oil supply source is supplied to the torque actuator, and the return oil from the torque actuator is supplied to the power cylinder side.

When the piston of the torque actuator reaches the stroke end, the tip of the rod fixed to the ball of the ball valve hits the wall surface of the housing, and the ball valve becomes neutral. When the ball valve becomes neutral as described above, both chambers of the torque actuator communicate with each other through the through hole. And
Pressure oil flows from the high pressure chamber to the low pressure chamber. for that reason,
Pressure oil from a pressure oil supply source is supplied to a power cylinder via a torque actuator.

(Effect of the Present Invention) According to the apparatus of the present invention, the pressure oil supply source for the power cylinder and the torque actuator can be shared, so that, for example, the pressure oil supply for driving the hydraulic cylinder for lifting and lowering the loading platform as in the related art. There is no need to provide a special source.

Further, since a torque actuator is used as an actuator for lifting and lowering the bed, the mounting space for the hydraulic cylinder is smaller than that of a conventional hydraulic cylinder.

Further, even when the piston of the torque actuator reaches the stroke end, the pressure oil from the pressure oil supply source is continuously supplied to the power cylinder via the through hole formed in the piston, so that the power cylinder can be operated. .

The ball valve provided in the through hole fixes the rod to the ball and opens when the tip of the rod hits the wall surface of the housing, so that no complicated device is required to control the ball valve. Help me. For example, a sensor for detecting the stroke position of the piston and a control mechanism for controlling the ball valve in response to a signal from the sensor are not required.

(Embodiment of the present invention) In the first embodiment shown in FIGS. 1 to 3, a vane pump P is provided in a casing C, and the vane pump P
A flow control valve FV and a high-pressure relief valve HR are connected in parallel to the discharge side of.

The main passage 11 connected to the vane pump P communicates with one port 12 of the switching valve D. The other port 13 of the switching valve D controls the power cylinder PS via the passage 14. Inflow port 15 of steering control valve SV
Connected to

When the steering control valve SV is in the neutral position, the inflow port 15, the outflow port 16, and the two cylinder ports 17, 18 maintain a so-called underlap state in which all of them communicate with each other. And the above passage
14 is connected to a low-pressure relief valve LR, and the maximum pressure of the power cylinder PS is controlled by the low-pressure relief valve LR.

Further, the actuator ports 19, 20 of the switching valve D
One of the actuator ports 19 is connected to one pressure chamber 21 of the torque actuator TA via the operation check valve OT, and the other actuator port 20 is connected to the other pressure chamber 22 of the torque actuator TA. . The torque actuator TA has a piston 23 slidably mounted in a housing 23 thereof,
A rack 25 is formed on one side of the piston 24. The sector gear 26 is meshed with the rack 25. Therefore, when the piston 24 moves left or right, the sector gear 26 rotates.

The piston 24 has a hole 27 penetrating the center thereof, and a ball valve 28 is provided in the center of the hole 27.
The detection rods 29 and 30 are fixed to the ball valve 28, and the tips of the detection rods 29 and 30 are exposed outside the hole 27. The ball valve 28 has pressure chambers 21 and 22
The pressure between the pressure chambers 21 and 22 is closed by the pressure difference between the pressure chambers 21 and 22. However, when the piston 24 reaches the stroke end, the detection rods 29 and 30 hit the wall surface of the housing 23, so that the ball valve 28 is forcibly opened and the two pressure chambers 21 and 22 communicate with each other.

As shown in FIG. 2, the torque actuator TA as described above is located at the center of rotation of the bed 2 and the shaft 31 of the sector gear 26 is attached to the bracket 32 of the bed.
It is fixed to. Therefore, the torque actuator TA
Is driven, the carrier 2 moves up and down accordingly.

Note that the rack 25 formed on the piston 24, a sexter gear 26 meshing with the rack 25, and the shaft 31 of the sexter gear 26 constitute a rotation mechanism of the present invention.

Now, when the switching valve D is held at the neutral position in the figure, the pressure oil from the vane pump P is supplied to the steering control valve SV via the main passage 11 → ports 12, 13 → passage 14. At this time, when the steering control valve SV is in the neutral position, the pressure oil is returned to the tank T via the outflow port 16 as it is. When the steering control valve SV is at the switching position, the pressure oil is supplied to one of the pressure chambers 33 or 34 of the power cylinder PS. The hydraulic oil in one of the other pressure chambers is returned to the tank T via the outflow port 16.

Then, when the switching valve D is switched to, for example, the left position in the drawing, the discharge oil of the vane pump P is supplied to the pressure chamber 21 via the port 12 → the actuator port 19 → the operation check valve OT. Therefore, the torque actuator
The TA piston 24 moves rightward in the drawing, and the sector gear 26 rotates. When the sector gear 26 rotates in this manner, the bed 2 rises accordingly.

The hydraulic oil in the pressure chamber 22 at this time flows into the steering control valve SV via the actuator port 20 → port 13 → passage 14, but if the steering control valve SV is at the neutral position, the hydraulic oil remains unchanged. Returned to tank T. When the steering control valve SV is at the switching position, the return oil from the pressure chamber 22 is supplied to the power cylinder PS.

Then, when the piston 24 reaches the stroke end, one of the detection rods 30 hits the wall surface of the housing 23, so that the ball valve 28 is forcibly opened and the pressure chambers 21 and 22 are communicated. If the two pressure chambers 21 and 22 are not communicated with each other at the stroke end of the piston 24, the discharge oil of the vane pump P is not supplied to the power cylinder PS when the stroke end is reached. That is, the power steering does not function when the carrier 2 is held at the highest position. Therefore, in order to prevent such a situation from occurring, when the piston 24 reaches the stroke end, the two pressure chambers 21 and 22 are communicated with each other, and the discharge oil of the vane pump P passes through the hole 27 to the power steering side. They are being supplied.

When the switching valve D is switched to the right position in the drawing,
The oil discharged from the vane pump P is supplied to the pressure chamber 22 via the port 12 and the actuator port 20.
With this discharge pressure, the operation check valve OT is opened. Accordingly, the piston 24 moves to the left in the drawing while discharging the hydraulic oil on the pressure chamber 21 side, rotates the sector gear 26, and lowers the carrier 2. The return oil from the torque actuator TA at this time is supplied to the steering control valve SV in the same manner as described above.

Then, the low-pressure relief valve LR of the circuit diagram shown in FIG.
FIG. 3 shows a configuration in which the switching valve D and the operation check valve OT are integrated.

The main body 35 includes a control spool 36 for the low-pressure relief valve LR.
, A switching spool 37 of the switching valve D, and an operation check valve OT.

The main body 35 has a port 12 communicating with the vane pump P.
The port 12 is always in communication with the first and second annular grooves 38 and 39 formed around the switching spool 37. When the switching spool 37 is in the neutral position shown in the figure, the first annular groove 38 is kept closed, and the second annular groove 39 is connected to the port 13 via the first annular groove 40 formed in the switching spool 37. I am trying to communicate with In addition, the port 13 communicates with the steering control valve SV via the relay chamber 41 and the passage 14.

When the switching spool 37 moves from the neutral position to the right in the drawing, communication between the second annular groove 39 and the port 13 is cut off, while the second annular groove 39 is formed in the second annular groove 42 formed in the spool 32. Communicate with

The second annular concave groove 42 is always in communication with the actuator port 19 which communicates with the operation check valve OT regardless of the moving position of the switching spool 37. Therefore, if the second annular groove 39 communicates with the second annular concave groove 42 as described above, the pressure oil from the port 12 flows out from the rising port 44 while pushing and opening the ball 43 of the operating check valve OT, and the torque actuator It is supplied to one pressure chamber 21 of TA.

Then, the return oil from the other pressure chamber 22 at this time is
While passing through the pilot chamber 46 from the descending port 45,
It flows into the actuator port 20 of the switching valve D.

When the switching spool 37 is moved rightward in the drawing as described above, the third annular groove formed in the switching spool 37 is moved.
47 and the third annular groove 48 formed on the main body 35 side communicate with each other.
The third annular groove 48 has a through hole formed along the axis of the spool 37 regardless of the moving position of the switching spool 37.
It is configured to always communicate with 49. Moreover, this through hole 49
Communicates with the port 13 at all times.

Therefore, the return oil that has flowed into the actuator port 20 as described above passes through the third annular concave groove 47 → the third annular groove 48 → the through hole 49 → the port 13 → the relay chamber 41 → the passage 14 to the steering control valve SV. Supplied to

When the switching spool 37 is moved in the opposite direction to the left in the drawing, the first annular groove 38 and the third annular groove 47 communicate with each other, and the third annular groove 48 and the second annular groove 42 are connected. Communicate.

Therefore, the pressure oil from the port 12 is supplied to the other pressure chamber 22 of the torque actuator TA via the actuator port 20 → the pilot chamber 46 → the descending port 45.
Since the load pressure at this time acts on the pilot piston 50 facing the pilot chamber 46, this pilot piston
Operate check valve with push rod 51 formed in 50
Push and open the ball 43 of the OT. When the operation check valve is opened in this manner, the return oil in the pressure chamber 21 flows through the operation check valve OT to the actuator port 19.
Flows into. Then, the return oil which has flowed into the actuator port 19 is supplied to the second annular concave groove 42 → the third annular groove 48 → the through hole.
It is supplied to the steering control valve SV via 49 → port 13 → relay room 41 → passage 14.

The control spool 36 of the low-pressure relief valve FR has one end facing the relay chamber 41 and the other end facing the spring chamber 52, and is normally operated by a spring 53 provided in the spring chamber 52. Hold position, relay room 41
And the tank port 54.

The relay chamber 41 and the spring chamber 52 are connected to a communication path 55.
Through the orifice.
Form 56.

Further, a pilot poppet 58 is incorporated in the control spool 36 of the low-pressure relief valve LR. That is, the inside of the spool 36 is hollow, and the drain port 57 is formed in the hollow portion. The hollow portion and the spring chamber 52 are communicated with each other, and a pilot poppet 58 is provided in the communication process.

Therefore, the pressure on the relay room 41 side is
When the pressure exceeds the set pressure of 58, the pilot poppet 58 opens. If the pilot poppet 58 opens, the relay room
Hydraulic oil on the 41 side passes through the orifice 56 and drain port 57
, A pressure difference around the orifice 56 is generated. The control spool 36 moves by the action of the differential pressure across the orifice 56, and a part of the pressure oil in the relay chamber 41
Return to tank T from 54. Thus, the low pressure relief valve
LR is what works.

According to the structure shown in FIG. 3 as described above, each of the low-pressure relief valve LR, the switching valve D, and the operation check valve OT is integrated into a single main body 35, so that the whole can be made compact. become.

In addition, since the low-pressure relief valve LR, the switching valve D, and the operation check OT are integrally incorporated, piping and the like become unnecessary, and the mounting space can be reduced accordingly.

The second embodiment shown in FIG.
The TA is located inside the hinge 3, which is the center of rotation of the carrier 2, and a link mechanism 58 is provided on the shaft 31 of the torque actuator. The other configuration is the same as that of the first embodiment.

[Brief description of the drawings]

1 to 3 show a first embodiment of the present invention.
FIG. 1 is a circuit diagram, FIG. 2 is an explanatory view showing an attached state, FIG. 3 is a sectional view showing a state in which a low-pressure relief valve, a switching valve, and an operation check valve are integrally incorporated, and FIG. FIG. 5 is an explanatory view showing an attached state of the embodiment, and FIG. 5 is an explanatory view of a conventional device. P: Vane pump as pressure oil supply source, FV: Flow control valve, HR: High pressure relief valve, D: Switching valve, PS: Power cylinder, SV: Steering control valve, LR: Low pressure relief valve , TA ... torque actuator, 21 ... pressure chamber, 22 ... pressure chamber, 23 ... housing, 24 ... piston, 25 ... rack, 26 ... sexda gear, 27 ... through-hole, 28 ... ... ball valve, 29 ... detection rod, 30 ...
Detection rod.

Claims (1)

(57) [Claims] 1. A pressure oil supply source, a steering control valve connected to the pressure oil supply source, a power cylinder connected downstream of the steering control valve, and a power cylinder connected upstream of the steering control valve. A switching valve for communicating the steering control valve with the pressure oil supply source when the vehicle is in neutral, a torque actuator connected to the switching valve, and converting the reciprocating motion of the piston of the torque actuator into rotational motion and dumping the torque by the rotational force. And a rotating mechanism for raising and lowering the loading platform, wherein the torque actuator comprises:
Chambers on both sides separated by a piston provided in the housing, a through hole formed in the axial direction of the piston and communicating the two chambers, and a communication between the two chambers provided in the through hole and caused by a pressure difference between the two chambers. And a rod fixed to the ball of the ball valve and protruding from the through hole into both chambers. When the piston reaches the stroke end, the tip of the rod contacts the wall surface of the housing. The ball valve becomes neutral and the two chambers communicate with each other through the through-hole, while the switching valve communicates with the pressure oil supply source and one of the chambers of the torque actuator when it is in the switching position. A hydraulic control device for a dump, wherein one of the other chambers and the steering control valve are connected to each other.