JP2003194217A - Switching valve and hydraulic circuit of hydraulic ally driven vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching valve which is switchable according to the flow rate of a hydraulic circuit, and a hydraulic circuit of hydraulic ally driven vehicle which is improved in operability by the switching valve. <P>SOLUTION: A valve element 47 of the switching valve 40 which is connected to either suction ports 8, 23 and 24 or discharge ports 10, 25 and 26 of hydraulic motors 7, 13 and 14 which are in parallel in each other is provided with throttled path 49 and a second throttled path 50. When differential pressure generated by the flow rate of pressurized fluid exceeds set pressure in front of or behind the throttled path 49 and the second throttled path 50, the valve element 47 which stands in the middle position moves towards valve seats 51 which are installed in front of or behind the valve body 47 and blocks the throttled path 49. Thus, a flow rate of pressurized fluid through hydraulic motors 7, 13 and 14 can be limited in accordance with the flow rate of the second throttled path 50. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-off valve for controlling a flow rate of a hydraulic circuit in order to operate a hydraulic motor, a hydraulic cylinder and the like as desired, and particularly to drive the hydraulic motors in parallel relationship with each other. The present invention relates to an on-off valve used in a hydraulic circuit of a hydraulically driven vehicle having wheels connected thereto.

[0002]

2. Description of the Related Art Conventionally, a hydraulic circuit 100 for a hydraulically driven vehicle as shown in FIG.
The hydraulic motor 102 (1) of the drive wheel 101 (103) is caused by (103) fitting into a recess on the traveling surface or removing the wheel.
When a large amount of pressure fluid flows into 04), the pressure fluid does not flow into the hydraulic motor 104 (102) of the other drive wheel 103 (101), and no driving force is generated in that drive wheel 103 (101). A well-known electromagnetic on-off valve 105 is connected to the hydraulic circuit 100 of the drive vehicle. By switching the electromagnetic on-off valve 105 with a switch or the like, a large amount of pressure fluid flows into the hydraulic motor 102 (104). The flow rate is restricted by the throttle passage 106 so that the other drive wheel 10
There is known one in which a hydraulic fluid is caused to flow into the hydraulic motor 104 (102) of No. 3 (101) to generate a driving force in the driving wheel 103 (101) so that the driving wheel 103 (101) escapes from the place (Japanese Patent Application Laid-Open No. 2003-101242). 2000-118247).

[0003]

However, the drive wheel 101 (103) on one side is fitted into a recess on the running surface or is removed from the drive wheel 101 (103) to cause the hydraulic motor 1 of the drive wheel 101 (103) to be removed.
Each time a large amount of pressurized fluid flows into 02 (104), the driver has to operate switches on the operation box to switch the electromagnetic on-off valve 105, which is troublesome. Then, the subject of this invention is providing the switching valve which can be switched according to the flow volume of a hydraulic circuit. Another object of the present invention is to provide a hydraulic circuit for a hydraulically driven vehicle in which operability is improved by an open / close valve that can be switched according to the flow rate of the hydraulic circuit.

[0004]

[Means for Solving the Problems] In order to solve the above problems,
The present application forms a flow path of a pressure fluid in a casing, and a valve body is slidably fitted in the flow path to partition the flow path with the valve body. Form a communicating throttle passage,
In the flow passage, a valve seat is provided in front of and behind the valve body to close the throttle passage by making pressure contact with the valve body when the valve body moves in either one of its moving directions. Further, a pair of biasing means capable of holding the valve body is provided at a neutral position where the valve body is opened with respect to the front and rear valve seats, and the throttle passage is provided from a flow passage on one side divided by the valve body. When the pressure fluid is passed through the throttle valve to the other side and the differential pressure generated by the flow rate of the pressure fluid before and after the throttle passage becomes equal to or higher than the set pressure, the valve element in the neutral position is biased to the other side. It is constructed so as to block the throttle passage by moving toward the valve seat on the other side against the biasing force of the means.

In addition to the above-mentioned throttle passage that is opened and closed, the valve body has a second throttle passage that always communicates with the flow passages in front of and behind the valve body regardless of the valve body position. Is a throttle degree smaller than the throttle degree of the throttle passage that is opened and closed.

There are various arrangements of the drive wheels of a hydraulically driven vehicle. When the drive wheels are provided on the left and right respectively, the front wheels and the rear wheels are respectively the drive wheels, and the front wheel is one wheel and the left and right rear wheels are respectively, There are various types, such as the case where the left and right front wheels and the left and right rear wheels are all driving wheels, the left and right front wheels are driving wheels, and the rear wheels are not driven.However, in the present application, the front wheels are connected to the front wheel driving hydraulic motor, A hydraulic drive vehicle in which the left and right rear wheels are respectively connected to the left and right rear wheel drive hydraulic motors, and the left and right rear wheel drive hydraulic motors are in parallel with each other in the hydraulic circuit and in parallel with the front wheel drive hydraulic motor. At
The open / close valve configured as described above was connected to either the discharge port or the suction port of each of the rear wheel drive hydraulic motors.

Further, in the present application, the front wheels are connected to the front wheel drive hydraulic motor, the rear wheels are connected to the rear wheel drive hydraulic motor, and the front and rear drive hydraulic motors are in a parallel relationship with each other in the hydraulic circuit. In a hydraulically driven vehicle, the on-off valve configured as described above is connected to either the discharge port or the suction port of each driving hydraulic motor.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments will be described with reference to the drawings. As a hydraulically driven vehicle, a case where it is applied to a compaction machine (road roller) 1 will be described here. In the hydraulic circuit 2 of the load roller 1 shown in FIG. 1, the fluid pressure pump 3 is a variable displacement hydraulic pump (for example, an axial swash plate type fluid pressure pump) capable of bidirectional flow due to the driving force of the engine 4. The discharge port 5, which is one of the pressure fluid supply / discharge ports of the pressure pump 3, is connected to an intake port 8 of a front wheel drive hydraulic motor 7 that drives a front steel rolling wheel (front wheel: front drive wheel) 6. The suction port 9, which is the other pressure fluid supply / discharge port of the fluid pressure pump 3, is connected to the discharge port 10 of the hydraulic motor 7. Further, in the fluid pressure pump 3, left and right rear wheel drive hydraulic motors 13 and 14 for independently driving left and right compaction tires (rear wheels) 11 and 12 as rear drive wheels are provided. The hydraulic motor 7 for driving 6 is connected in parallel, and the left and right hydraulic motors 13, 14 are also connected in parallel with each other.

A main flow path 20 is connected to the discharge port 5 of the fluid pressure pump 3. The main flow path 20 is branched into two flow paths 21 and 22 on the way. One branch flow passage 21 is connected to an intake port 23 which is one pressure fluid supply / discharge port of the hydraulic motor 13, and the other branch flow passage 22 is an intake port which is one pressure fluid supply / discharge port of the hydraulic motor 14. It is connected to port 24. Hydraulic motor 13 and hydraulic motor 1
Discharge ports 25 and 2 which are the other pressure fluid supply and discharge ports
The channels 6 and 6 are connected to the flow paths 27 and 28, respectively, which are provided with on-off valves 40a and 40b which will be described later. The flow paths 27 and 28 join together and are connected to the suction port 9 of the fluid pressure pump 3 via the main flow path 29. In addition, 30 is a check valve,
Reference numeral 31 is a relief valve, and 32 is a charge pump.

The on-off valve 40 shown in FIG. 2 will be described.
A fluid passage 44 of a fluid having a large diameter hole 42 and a pair of small diameter holes 43 is formed so as to penetrate the casing 41. A closing member 45 is attached by a screw member 46 so as to close the large diameter hole portion 42 of the flow path 44. One small-diameter hole portion 43 of the flow path 44 is formed in the closing member 45 so as to penetrate the closing member 45. The valve body 47 is slidably fitted in the large-diameter hole portion 42 of the flow channel 44 to define the flow channel 44 by the valve body 47. In the valve body 47, the small diameter portions 47b are axially projected from both end surfaces of the large diameter portion 47a, respectively.
Abutting portion 4 with which a biasing means 52 described later abuts around 7a
7c is provided. Then, the divided flow path 44
A seal member 48 is attached to the contact portion 47c so that the pressurized fluid does not flow in between. The valve body 47 has a valve body 47.
In addition to the opening / closing throttle passage 49 provided in the large diameter portion 47a of the
A second throttle passage 50 that always connects A and 44B is provided,
The second throttle passage 50 has a smaller throttle degree than the throttle passage 49 that is opened and closed. As shown in FIGS. 2 and 3, the throttle passage 49 is composed of orifice holes provided above and below the axis of the valve body 47. A valve seat 51 that closes the throttle passage 49 by press-contacting the small diameter portion 47b of the valve body 47 when the valve body 47 moves in one of the moving directions of the flow path 44 before and after the valve body 47. Is provided. Before and after the valve element 47, a neutral position where the valve element 47 is opened with respect to the front and rear valve seats 51 (state of FIG. 2).
Further, spring members 52a and 52b exemplified as a pair of biasing means capable of holding the valve body 47 are provided.

In this on-off valve 40, when a large amount of pressure fluid Q1 is passed from the flow passage 44A on one side to the throttle passage 49 and the second throttle passage 50, the large flow amount Q1 of the pressure fluid is increased to the throttle passage 49 and the second passage. Because it is greatly throttled by the second throttle passage 50,
The pressurized fluid comes to stay in the flow passage 44A on one side, and has a set pressure before and after the throttle passage 49 and the second throttle passage 50 (differential pressure corresponding to the flow rate Q flowing in the hydraulic circuit during normal rolling work). ΔP) or more of the differential pressure is generated, so that the valve member 47 in the neutral position in which the valve is opened is on the other side of the spring member 52b.
The flow passage 4B on the other side moves toward the valve seat 51 of the flow passage 44B on the other side to close the throttle passage 49 and the flow passage 4 on the other side.
4B to the flow rate Q passing through the second throttle passage 50.
It is limited to 2 (state of FIG. 4). Then, when the flow rate of the pressure fluid returns to the flow rate Q by causing a part of the pressure fluid staying in the one side flow passage 44A to flow into the other flow passage, the valve body 47 is urged by the spring member 52b. It is pushed back to the neutral position again (state of FIG. 2). Incidentally, when the pressurized fluid is passed from the other flow passage 44B to the throttle passage 49 and the second throttle passage 50 at a large flow rate Q1, the valve body 47 is resisted against the urging force of the spring member 52a on one side and is on one side. Channel 4
The throttle passage 49 is closed by moving toward the valve seat 51 of 4A.

During a normal rolling operation, the pressure oil (pressure fluid) discharged from the discharge port 5 of the fluid pressure pump 3 flows to the front wheel drive hydraulic motor 7 for driving the front rolling wheel 6, The fluid pressure pump 3 is driven by rotating the compaction wheel 6 on the front side.
Return to. On the other hand, by the pressure oil flowing from the main flow path 20 to the branch flow paths 21 and 22, the rear left and right compaction tires (rear wheels) 11,
Left and right rear wheel drive hydraulic motors 13 and 14 that drive 12 independently of each other are driven, respectively, and rear left and right compaction tires 1
1, 12 are driven and rotated. The pressure oil that has passed through the left and right rear wheel drive hydraulic motors 13 and 14 returns to the fluid pressure pump 3 via the flow passage 27 and the main flow passage 29 on the hydraulic motor 13 side. Further, on the hydraulic motor 14 side, it returns to the fluid pressure pump 3 via the flow passage 28 and the main flow passage 29.

During running, for example, when one of the left and right rolling compaction tires (herein referred to as compaction rolling tire 11) is fitted in a depression or muddy road surface, the rolling compaction tire 11 is A large amount of pressure oil flows into the hydraulic motor 13 that idles to drive the compaction tire 11, and the flow rate Q of the pressure oil to the other hydraulic motors 7 and 14 is reduced, so that the driving force cannot be generated. I can't escape from. However, the on-off valve 4
0a, depending on the large flow rate Q1 of the pressure oil, the throttle passage 49
Since a differential pressure equal to or higher than the set pressure is generated before and after the second throttle passage 50, the movement of the valve body 47 closes the throttle passage 49, and the flow rate of the pressure oil to the hydraulic motor 13 into which a large amount of pressure oil flows is increased. It is possible to limit the passage flow rate Q2 of the second throttle passage 50.
As a result, a part of the pressure oil accumulated in the on-off valve 40a flows into the other hydraulic motors 7 and 14, and a driving force is generated in the compaction wheels 6 and compaction tires 12. Or, you can get out of the muddy state. By providing the second throttle passage 50 in this manner, it is possible to prevent the hydraulic motor 13 whose rotational speed has been increased from being suddenly stopped. After that, the valve body 47 of the on-off valve 40a
Is returned to the neutral position, and the road roller 1 again performs a normal rolling operation.

Next, another embodiment will be described. 5, in addition to the embodiment of FIG. 1, the forward discharge port 1 of the front wheel drive hydraulic motor 7 that drives the front compaction wheel 6
In the middle of the return circuit from 0 to the fluid pressure pump 3, the on-off valve 40
c is interposed. Also in this configuration, the front compaction wheel 6 or the rear left / right compaction tire 1 is formed in the depression or the like.
When either one of the drive wheels 1 and 12 (here, the compaction wheel 6 and the compaction tire 11) is fitted,
The flow rate of the pressure oil to the hydraulic motors 7 and 13 can be limited to the flow rate Q2 passing through the second throttle passage 50 by the open / close valves 40a and 40c. As a result, a part of the pressure oil accumulated in the on-off valves 40a and 40c flows into the hydraulic motor 14 and a driving force is generated in the compaction tire 12, so that the pressure oil enters the depression or enters the muddy state. You can escape from the state. After that, the valve bodies 47 of the on-off valves 40a and 40c are returned to the neutral position, and the load roller 1 again performs the normal rolling operation.

Further, another embodiment will be described. The same parts as those described above are designated by the same reference numerals, and description thereof will be omitted. Figure 6
The case where the front and rear wheels are one compaction wheel 6 and 6a respectively is shown, and each compaction wheel 6 and 6a is directly connected to the hydraulic motors 7 and 7A to drive them. The discharge port 8A of the rear wheel drive hydraulic motor 7A that drives the rear compaction wheel 6a.
On-off valve 40c in the middle of the return circuit from fluid pressure pump 3 to
Is interposed. Also in this embodiment, when either the front or rear compaction wheel (here, the rear compaction wheel 6a) is fitted in the depression or the like, the opening / closing valve 40d causes the hydraulic motor 7A of the compaction wheel 6a to move. The flow rate of the pressure oil can be limited to the flow rate Q2 passing through the second throttle passage 50. As a result, a part of the pressure oil accumulated in the on-off valve 40d flows into the hydraulic motor 7 of the compaction wheel 6 and a driving force is generated in the compaction wheel 6. You can escape from a trapped state. After that, the valve element 47 of the on-off valve 40c is returned to the neutral position, and the load roller 1 again performs the normal compaction work traveling.

In the case where the hydraulic oil supply to the front wheel drive hydraulic motor 7 and the rear wheel drive hydraulic motors 13 and 14 described in the first to third embodiments does not affect each hydraulic motor even if it is suddenly changed. The on-off valve 40A can be configured as shown in FIG. In this on-off valve 40A, when the pressurized fluid is passed at a large flow rate Q1 from the flow passage 44A on one side to the throttle passage 49,
Since the large flow rate Q1 of the pressure fluid is greatly throttled by the throttle passage 49, the pressure fluid is retained in the flow passage 44A on one side, and the set pressure is set before and after the throttle passage 49 (the hydraulic circuit during a normal rolling operation). Since a pressure difference equal to or higher than the pressure difference ΔP1) corresponding to the flow rate Q flowing to the valve is generated, the valve element 47 in the neutral position, which is in the valve open state, resists the biasing force of the spring member 50b on the other side. The throttle passage 49 is closed by moving toward the valve seat 51 of the flow passage 44B. From this,
When the opening / closing valve 40A is used in any of the above-described first to third embodiments (for example, FIG. 8), a large amount of pressure oil flows in by closing the throttle passage 49, and the rotational speed of the hydraulic motor 13 increases. 14) is abruptly stopped, but the valve body 47 of the on-off valve 40A is returned to the neutral position by the pressure oil accumulated in the on-off valve 40A flowing into another flow path. You can get exactly the same effect.

Therefore, the throttle passage 49 and the second throttle passage 50 are provided in the valve body 47 of the opening / closing valve 40, and the throttle passage 49 is provided.
When the differential pressure generated by the flow rate of the pressure fluid before and after the second throttle passage 50 becomes equal to or higher than the set pressure, the valve body 47 in the neutral position moves toward the one valve seat 51 and closes the throttle passage 49. Therefore, in the flow path into which a large amount of pressure fluid has flowed, the flow rate of the pressure fluid can be automatically limited only to the passage amount of the second throttle passage 50.
03) is fitted into a recess on the running surface or is derailed to cause the hydraulic motor 102 (10) of the drive wheel 101 (103) to move.
Every time a large amount of pressure fluid flows into 4), it is not necessary for the driver to operate the switch or the like on the operation box to switch the opening / closing valve 105 on the flow path side into which a large amount of pressure fluid has flown. This leads to improved operability.

[0018]

As described above, according to the present invention, the valve body is slidably fitted in the flow passage provided in the casing, the valve body is provided with the throttle passage, and the flow rate of the pressurized fluid is provided before and after the throttle passage. When the differential pressure caused by is equal to or higher than the set pressure, the valve element in the neutral position moves to block the throttle passage, and when the differential pressure reaches the set pressure, the valve element is returned to the neutral position so that it enters the open / close valve. The flow rate of the pressurized fluid can be limited. In addition, when the drive wheel goes into a dent or runs idle due to muddyness, the valve element moves due to the flow rate of the pressurized fluid entering the on-off valve, so the driver operates the switches on the operation box each time. Further, since it is not necessary to control the flow path side into which a large amount of pressurized fluid has flowed, the operability of the hydraulically driven vehicle is improved.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit in which the on-off valve of the present invention is used in a compaction vehicle.

FIG. 2 is a sectional view of an on-off valve.

FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, in which a spring member is omitted.

FIG. 4 is a reference diagram showing a state in which a large amount of pressurized fluid has flowed in from a flow path on one side.

FIG. 5 is another embodiment.

FIG. 6 is still another embodiment.

FIG. 7 is a view showing another embodiment of the open / close valve.

8 is a hydraulic circuit in which the valve body of FIG. 7 is used in a compaction vehicle.

FIG. 9 is a diagram showing a conventional hydraulic circuit.

[Explanation of symbols]

1 Road roller 2 hydraulic circuit 6 front wheels 7 Front wheel hydraulic motor 8 suction ports 9 discharge ports 10,11 Rear wheel 13, 14 Rear wheel drive hydraulic motor 40 open / close valve 41 casing 44 channel 47 Disc 49 throttle passage 50 Second throttle passage 51 seat 52 Spring member

Claims (4)

[Claims] 1. A flow passage for a pressure fluid is formed in a casing, and a valve body is slidably fitted in the flow passage to divide the flow passage by the valve body. A valve that forms a throttle passage communicating with a passage, and closes the throttle passage by pressing the valve body before and after the valve body when the valve body moves to either side in the moving direction. A seat is provided, and a pair of urging means capable of holding the valve body at the neutral position where the valve body is opened to the front and rear valve seats are further provided in front of and behind the valve body, and are partitioned by the valve body. When a pressure fluid was passed from one side flow path to the other side through the throttle passage and the differential pressure generated by the flow rate of the pressure fluid before and after the throttle passage was equal to or higher than the set pressure, it was in the neutral position. The valve body is configured to move toward the valve seat on the other side against the biasing force of the biasing means on the other side to close the throttle passage. An on-off valve characterized by. 2. The valve body has, in addition to the throttle passage that is opened and closed, a second throttle passage that always communicates with the flow passages before and after the valve body regardless of the valve body position. The opening / closing valve according to claim 1, wherein the opening degree is smaller than the opening degree of the opening / closing passage to be opened / closed. 3. The front wheels are connected to a front wheel drive hydraulic motor, the left and right rear wheels are respectively connected to left and right rear wheel drive hydraulic motors, and the left and right rear wheel drive hydraulic motors are parallel to each other in a hydraulic circuit. Further, in the hydraulically driven vehicle in parallel with the front wheel driving hydraulic motor, the on-off valve according to claim 1 or 2 is connected to either one of the discharge port and the suction port of each of the rear wheel driving hydraulic motors. A hydraulic circuit for a hydraulically driven vehicle. 4. A hydraulic drive in which front wheels are connected to a front wheel drive hydraulic motor, rear wheels are connected to a rear wheel drive hydraulic motor, and the front and rear drive hydraulic motors are in a parallel relationship in a hydraulic circuit. A hydraulic circuit for a hydraulically driven vehicle, wherein the on-off valve according to claim 1 or 2 is connected to either one of a discharge port and an intake port of each of the drive hydraulic motors.