JP2009228872A - Valve device for construction vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve device dispensing with a conventional supply port body 4, without making a difference in a pressure loss in response to the switching direction of a spool. <P>SOLUTION: A pump passage 36 communicating with pump ports 42 and 43 of a first directional control valve V1 is formed in a valve housing 23 of a second directional control valve V2. A recessed part 38 is also formed on a continuously connecting surface between the valve housing 23 of the second directional control valve V2 and a valve housing 39 of the first directional control valve V1, and the pump ports 42 and 43 are always communicated via this recessed part 38. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a valve device that controls a pair of travel motors of a construction vehicle.

  As this type of valve device, one described in Patent Document 1 has been conventionally known. FIG. 4 shows a schematic diagram of this conventional device. In this conventional valve device, a plurality of directional switching valves for controlling each actuator are connected to form a valve connecting body 1, and among the directional switching valves constituting these valve connecting bodies 1, the directional switching valve 2 Controls one traveling motor M1, and the direction switching valve 3 controls the other traveling motor M2. And these direction switching valves 2 and 3 have the supply port main body 4 interposed between them. A pair of pumps P1 and P2 are individually connected to the supply port body 4, and one pump P1 is communicated with one traveling motor M1 via the direction switching valve 2, and the other pump P2 is connected with the direction. The other travel motor M2 communicates with the switching valve 3.

FIG. 5 shows a cross section of the direction switching valves 2 and 3. The direction switching valves 2 and 3 form a neutral flow path 6 in the valve housing 5 and pump ports 7 and 8 communicating with the pump on both sides thereof. A spool 9 is slidably incorporated in the valve housing 5 and annular grooves 10 and 11 are formed in the spool 9.
When the spool 9 is in the illustrated neutral position, the pump ports 7 and 8 communicate with the neutral flow path 6 via the annular grooves 10 and 11. The neutral flow path 6 communicates with a tank (not shown) via a neutral flow path of another direction switching valve constituting the valve connecting body 1, and when the spool 9 moves to the left or right, the neutral position is generated by the spool 9. The flow path 6 is closed.

Further, a bridge passage 12 is formed in the valve housing 5, and the bridge passage 12 communicates with the pump port 7 through a passage 13. Further, the bridge passage 12 communicates with one actuator port 15 via an annular groove 14 formed in the spool 9 when the spool 9 moves in the right direction of the drawing, and when the spool 9 moves in the left direction of the drawing, 9 communicates with the other actuator port 17 through an annular groove 16 formed in the groove 9.
Reference numeral 18 in the figure denotes a tank passage formed in the valve housing 5, and when the spool 9 moves to the left in the drawing, it communicates with one actuator port 15 via the annular groove 14, and the spool 9 moves to the right. When it moves, it communicates with the other actuator port 17 via the annular groove 16.

  When the spool 9 of the directional switching valve as described above is moved in the left direction in the drawing, the neutral flow path 6 is closed corresponding to the annular groove 11. When the neutral flow path 6 is closed, the communication between the pump and the tank is interrupted, so that the pressure fluid flowing into the pump port 7 flows out from the actuator port 17 through the bridge path 12 and the annular groove 16 from the path 13. To do. The return fluid from the actuator port 15 flows out to the tank passage 18 via the annular groove 14.

Further, when the spool 9 is moved in the right direction in the drawing, the neutral flow path 6 is also closed, and the pressure fluid flowing into the pump port 7 flows from the actuator port 15 from the passage 13 via the bridge passage 12 and the annular groove 14. leak. The return fluid from the actuator port 17 flows out to the tank passage 18 via the annular groove 16.
JP 11-344143 A

In the conventional valve device as described above, the fluid from the pump port 7 is guided to the passage 13 regardless of whether the spool 9 moves in the left or right direction. For example, the spool 9 moves in the left direction. In this case, since the annular groove 10 is interposed between the pump port 7 and the passage 13, the flow passage area is sufficiently ensured. However, when the spool 9 moves in the right direction, the annular groove 10 is not interposed between the pump port 7 and the passage 13, and accordingly, the flow path area is reduced and the flow path resistance is also increased.
If the flow path resistance is different when the spool 9 is switched to the left and right as described above, for example, in a tandem circuit that drives a pair of travel motors with a single pump, the pressure loss depends on the switching direction of the spool 9. There was a problem that a difference occurred in the vehicle, which caused the vehicle to turn.

Further, as shown in FIG. 4, a circuit in which a pair of pumps P1 and P2 are connected in parallel to the traveling motors M1 and M2 requires the supply port main body 4, but the position of the supply port main body 4 is It is naturally identified in terms of functionality. Therefore, there has been a problem that the degree of freedom in design is impaired with respect to the layout of each direction switching valve. Further, the necessity of the supply port main body 4 as described above increases the number of parts correspondingly, which also causes an increase in cost.
An object of the present invention is to provide a valve device in which there is no difference in pressure loss depending on the switching direction of the spool, and in which a conventional supply port body is unnecessary.

  According to the present invention, a plurality of direction switching valves are connected to form a valve connecting body, and a separate pump is associated with each of the pair of traveling motors to control one traveling motor and the other. A second directional control valve for controlling the traveling motor is adjacent in the valve connecting body. The pump passage communicating with the pump that supplies the pressure fluid to one of the traveling motors is connected to the pump port of the first direction switching valve through the valve housing of the second direction switching valve. . The valve housing of the second direction switching valve includes a neutral flow path communicating with the tank, a pair of pump ports formed on both sides of the neutral flow path, and a bridge passage communicating with the pump port. ing. In addition, when the spool is slidably incorporated in the valve housing and the spool is in the neutral position, both pump ports communicate with the neutral flow path, and the spool is switched from the neutral position to the switching position. Any one of the pump ports communicates with the bridge passage. Furthermore, when the second directional control valve is connected to the first directional control valve, a recess is formed on the connecting surface of the valve housing of the second directional control valve so that the pair of pump ports are always in communication. A pump passage that communicates with a pump that supplies pressure fluid to one of the traveling motors is passed through between the bridge passage of the second direction switching valve and the spool.

According to this invention, the pump passage communicating with the first direction switching valve is made to penetrate the valve housing of the second direction switching valve and communicates with the pump passage of the first direction switching valve. Thus, without using the supply port body, each of the pair of pumps can be communicated with each traveling motor via a predetermined direction switching valve.
Accordingly, since the supply port main body is not used, the degree of freedom in designing the layout is increased and the cost is reduced.

  Further, a pump passage communicating with the first direction switching valve is passed through the valve housing of the second direction switching valve, but even if this pump passage is passed through the valve housing of the second direction switching valve. The operability of the second directional control valve is not affected. That is, by forming the recess as described above and always communicating the pair of pump ports, the flow path area passing through the pump port is sufficient even if the second direction switching valve is switched to the left or right. Can be secured.

  As shown in FIG. 1, the valve device of this embodiment forms a valve connecting body A by connecting a plurality of direction switching valves, and also includes a first direction switching valve V1 that controls one traveling motor M1 and the other. The second directional control valve V2 that controls the traveling motor M2 is adjacent to each other. An inlet 19 is connected to the outside of the second direction switching valve V <b> 2, and an outlet 20 is connected to the opposite end of the inlet 19. The inlet 19 is formed with a pair of ports 21 and 22, one port 21 is connected to the pump P 1, and the other port 22 is connected to the pump P 2.

As shown in FIG. 3, the second direction switching valve V2 has a neutral flow path 24 formed in the valve housing 23 and pump ports 25 and 26 communicating with the pump P2 on both sides thereof. A spool 27 is slidably incorporated in the valve housing 23 and annular grooves 28 and 29 are formed in the spool 27.
When the spool 27 is in the illustrated neutral position, the pump ports 25 and 26 communicate with the neutral flow path 24 via the annular grooves 28 and 29. The neutral flow path 24 communicates with a tank (not shown) via a neutral flow path of another direction switching valve constituting the valve connecting body A, and when the spool 27 moves to the left or right, the neutral position is generated by the spool 27. The flow path 24 is closed.

Further, a bridge passage 30 is formed in the valve housing 23 of the second direction switching valve V <b> 2, and this bridge passage 30 communicates with the pump port 25 through a passage 37.
Further, the bridge passage 30 communicates with one actuator port 32 via an annular groove 31 formed in the spool 27 when the spool 27 moves in the right direction of the drawing, and when the spool 27 moves in the left direction of the drawing, 27 communicates with the other actuator port 34 through an annular groove 33 formed in the member 27.
Reference numeral 35 in the figure denotes a tank passage formed in the valve housing 23. When the spool 27 moves leftward in the drawing, it communicates with one actuator port 32 via the annular groove 31, and the spool 27 moves rightward. When it moves, it communicates with the other actuator port 34 via the annular groove 33.

As shown in FIG. 3, the valve housing 23 of the second direction switching valve V2 as described above has a position between the bridge passage 30 and the spool 27 and facing the pump port 26. A pump passage 36 communicating with the first direction switching valve V1 is passed through.
Further, as shown in FIG. 2, the valve housing 23 is formed with a recess 38 on the connecting surface when the valve housing 23 is connected to the valve housing 39 of the first direction switching valve V1, and the recess 38 and the first A passage is formed in combination with the connecting surface of the valve housing 39 of the direction switching valve V1, and the pair of pump ports 25 and 26 are always in communication with the bridge passage 30 through this passage.

  The reason why the recesses 38 are provided and the pump ports 25 and 26 are always in communication as described above is because the pump passage 36 is formed in the valve housing 23. That is, if the pump passage 36 is formed particularly inside the bridge passage 30, the symmetry of the second direction switching valve V2 cannot be maintained. For this reason, the control characteristics at the time of switching the left and right of the spool 27 may be different. However, if the pump ports 25 and 26 are always communicated via the recess 38 as described above, such a problem is caused. Disappear.

  On the other hand, as shown in FIG. 2, the first direction switching valve V1 incorporates a spool 40 in the valve housing 39 so as to be slidable, and in the same manner as the second direction switching valve V2, Pump ports 42 and 43 are formed on both sides of the neutral flow path 41, and the pump ports 42 and 43 are communicated with a pump passage 36 formed in the valve housing 23 of the second direction switching valve V2.

  The valve housing 39 is formed with a bridge passage 49 similar to that of the second direction switching valve V2. This bridge passage 49 is connected to the pump port 42 or 43 depending on the switching position of the spool 40. It communicates with either. Further, the bridge passage 49 communicates with one actuator port 45 via an annular groove 44 formed in the spool 40 when the spool 40 moves in the right direction of the drawing, and when the spool 40 moves in the left direction of the drawing, 40 communicates with the other actuator port 47 through an annular groove 46 formed in 40.

  Reference numeral 48 in the figure denotes a tank passage formed in the valve housing 39. When the spool 40 moves to the left in the drawing, it communicates with one actuator port 45 through the annular groove 44, and the spool 40 moves to the right. When it moves, it communicates with the other actuator port 47 through the annular groove 46.

According to this embodiment as described above, the pump passage 36 communicated with the pump P1 that supplies the pressure fluid to the one traveling motor M1 passes through the valve housing 23 of the second direction switching valve V2, Since it communicates with the pump ports 42 and 43 of the first direction switching valve V1, the supply port body 4 is not required unlike the conventional valve device. Therefore, the desired effect of the present invention can be exhibited without regret.
Further, the pump passage 36 communicating with the first direction switching valve V1 is passed through the valve housing 23 of the second direction switching valve V2, but this affects the operability of the second direction switching valve V2. There is nothing.

It is a schematic diagram which shows embodiment of this invention. It is sectional drawing of the state which connected the 1st, 2nd direction switching valve. It is sectional drawing of a 2nd direction switching valve. It is a schematic diagram of the conventional valve apparatus. It is sectional drawing of the direction switching valve of the conventional valve apparatus.

Explanation of symbols

M1, M2 Traveling motor P1, P2 Pump A Valve connecting body V1 First direction switching valve V2 Second direction switching valve 23 Valve housing of the second direction switching valve 24 Neutral flow path 25, 26 Second direction switching valve Pump port 27 Spool of second direction switching valve 30 Bridge passage 36 Pump passage 38 Recess 39 Housing of first direction switching valve 42, 43 Pump port of first direction switching valve

Claims (1)

  A plurality of directional control valves are connected to form a valve connecting body, and a separate pump is associated with each of the pair of travel motors, and the first directional control valve for controlling one travel motor and the other travel motor are provided. A second directional control valve to be controlled is adjacent in the valve connecting body, and a pump passage communicating with a pump that supplies pressure fluid to one of the traveling motors penetrates the valve housing of the second directional switching valve. The valve housing of the second direction switching valve is in communication with the pump port of the first direction switching valve, the neutral flow path communicating with the tank, and a pair of pumps formed on both sides of the neutral flow path A port and a bridge passage communicating with the pump port, and a spool is slidably incorporated in the valve housing, and the spool is in a neutral position. When both the pump ports communicate with the neutral flow path and the spool switches from the neutral position to the switching position, one of the pump ports communicates with the bridge passage, and the second direction switching valve is When connected to the first direction switching valve, a recess is formed on the connecting surface of the valve housing of the second direction switching valve so that the pair of pump ports are always in communication, and pressure fluid is supplied to one traveling motor. A construction vehicle valve device in which a pump passage communicating with a pump is passed between a bridge passage of a second direction switching valve and a spool.

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