JP3891750B2 - Holding valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention opens and closes in conjunction with solenoid on / off control associated with the operation of switching between operation and stop of the hydraulic drive device, and maintains the load as it is by closing operation due to stop of the hydraulic drive device It is related with the improvement of the holding valve equipped with.
[0002]
[Prior art]
Conventionally, as a holding mechanism for maintaining the load as it is with the stop of the hydraulic drive device, for example, as disclosed in JP-A-2-255005, the closed state is maintained when the hydraulic drive device is stopped. It is known that the holding valve that holds the load is opened using the pilot pressure generated by the throttle mechanism at the same time as the operation of the hydraulic drive device is started.
[0003]
In addition, as disclosed in Japanese Patent Application Laid-Open No. Sho 62-288702 , a sub valve is switched by a solenoid at the same time as the operation of the hydraulic drive device is started, and a pilot pressure is applied to the holding valve by the sub valve to open, or As disclosed in Japanese Patent Application Laid-Open No. 6-294149, there is also known one in which a holding valve is directly pushed open by a solenoid simultaneously with the start of operation of a hydraulic drive device.
[0004]
[Problems to be solved by the invention]
However, as in the above-mentioned Japanese Patent Application Laid-Open No. 2-255005, in the system in which the holding valve is opened using the pilot pressure, the pilot pressure is increased until the required pressure is reached by mounting the throttle mechanism. Even if devised, the pilot pressure may not be increased sufficiently depending on the operating conditions. Therefore, the holding valve causes hunting due to the balance with the return pressure and the operation of the hydraulic drive unit is unstable. There is a fear of becoming.
[0005]
On the other hand, in Japanese Patent Application Laid-Open No. 62-288702, the solenoid is excited and the pilot pressure is applied to the holding valve by switching the sub-valve so as to release it. While the possibility of stabilization can be eliminated, the holding valve does not open unless the circuit pressure becomes equal to or higher than the cracking pressure even when the solenoid is excited, and the passage pressure loss becomes higher than the cracking pressure of the holding valve.
[0006]
In that respect, the one disclosed in Japanese Patent Laid-Open No. Hei 6-294149 is configured such that the holding valve is directly pushed open by a solenoid, so that the problems such as the former two can be easily solved. Although it is excellent, however, not only the return spring force but also the suction force that overcomes the hydraulic pressure acting on the valve poppet of the holding valve is required to open the holding valve, so that the solenoid becomes large Will have.
[0007]
Therefore, the object of the present invention is to switch the valve poppet using a small solenoid, only by applying a suction force that overcomes the return spring force regardless of the hydraulic pressure acting on the valve poppet with respect to the solenoid. It is to provide a direct switching holding valve by a solenoid.
[0008]
An object of the present invention described above is to provide a valve poppet for controlling the connection of a pair of input / output ports intermittently by making contact with and separating from a valve seat provided on the inner surface of the valve sleeve inside a valve sleeve having a pair of input / output ports. In a direct-switching type holding valve that is slidably inserted and controlled to be opened and closed by the restoring force of the return spring and the driving force of the solenoid, these valves are kept oiltight at both ends of the valve poppet. The both ends of the poppet define a flow path that leads from one input / output port to the other input / output port through the valve seat and a drain chamber that is located on the tip side of the valve poppet and in which a return spring is interposed , and It is taken equal to the outer diameter at both ends of the valve seat and the valve poppet, the valve sleeve Combine the body of the solenoid proximally communicates to the drain chamber of the distal end side of the body of the solenoid in through holes bored in the valve poppet, the proximal sleeve valve seat is formed a valve sleeve on the end portion This is achieved by dividing the base sleeve and the distal end sleeve into two members, and connecting the proximal end sleeve and the distal end sleeve in a concentric state by an inlay to form a single-piece valve sleeve .
[0009]
That is, with the above configuration, the holding valve of the present invention opens the valve seat on the valve sleeve side by overcoming the restoring force of the return spring by receiving the force from the solenoid by exciting the solenoid. The flow of pressure oil from one input / output port in the sleeve to the other input / output port is allowed.
[0010]
Conversely, if the solenoid is turned off and switched to a non-excited state, the valve poppet is pushed back by the restoring force of the return spring to close the valve seat on the valve sleeve side, and one input / output port is connected to the other input / output port. Hold the load by blocking the flow of pressure oil to return to the port.
[0011]
On the other hand, at the time of the above operation, the solenoid portion is connected to the drain chamber on the opposite side through a hole formed in the valve poppet, and the flow path connecting the pair of input / output ports to each other is a valve seat. Even if high-pressure oil acts on either one or both regardless of opening and closing of the valve, the pressure receiving areas of the valve poppet are kept equal to each other.
[0012]
As a result, the hydraulic pressure does not have any influence on the switching operation of the valve poppet by the solenoid on / off control, and therefore the holding valve is hunting like the other types of conventional holding valves described above. It is necessary to have a large solenoid with a suction force that can overcome the hydraulic pressure acting on the valve poppet of the holding valve. Such problems can be solved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Here, in order to facilitate understanding of the contents of the invention, before describing the embodiment of the direct switching type holding valves 1a, 1b by the solenoid of the present invention, the holding valves 1a, 1 An example of use of 1b will be described with reference to FIG.
[0014]
As illustrated in FIG. 2, the solenoid direct switching type holding valves 1 a and 1 b according to the present invention include a fixed displacement pump 22 and a reservoir 23 that are rotated forward and backward by an electric motor 21, check valves 24 a and 24 b, and hydraulic pressure. Used in combination with the cylinder 25.
[0015]
That is, the holding valves 1a and 1b are switched to the open state by the excitation of the solenoids 11a and 11b as the electric motor 21 is driven to rotate, and the electric motor 21 selects the fixed displacement pump 22 in either the forward or reverse direction. Rotational drive.
[0016]
As a result, the fixed displacement pump 22 allows the hydraulic oil in one hydraulic oil chamber 25a, 25b of the hydraulic cylinder 25 to be switched from the circuits 26a, 26b to the open state according to the rotation direction at that time. Inhale through one side of 1b.
[0017]
Subsequently, the hydraulic oil sucked into the fixed capacity pump 22 is now opened from the opposite circuits 27b and 27a by opening the holding valves 1b and 1a before switching to the hydraulic oil chamber on the opposite side of the hydraulic cylinder 25. The hydraulic cylinder 25 is selectively actuated in both forward and reverse directions by being pushed into 25b and 25a.
[0018]
A circuit 28 indicated by a broken line is a drain circuit for recovering the internal leakage hydraulic fluid of the holding valves 1a and 1b to the reservoir 23, and the circuits 29a and 29b are check valves 24a and 24b, respectively. The hydraulic oil that has become deficient due to internal leakage due to co-operation is supplied from the reservoir 23 to the suction side by opening the check valves 24a and 24b.
[0019]
Next, an embodiment which is a specific configuration example of the direct switching type holding valves 1a and 1b by the solenoid of the present invention will be described with reference to FIG.
[0020]
The holding valves 1a and 1b are in contact with and separated from the valve seat 5 provided on the inner surface of the valve sleeve 4 with respect to the inside of the valve sleeve 4 having a pair of input and output ports 2 and 3. A slidable valve poppet 6 for intermittently controlling communication is provided.
[0021]
The valve sleeve 4 is attached by screwing the input / output port 2 to the pump ports 7a and 7b and the input / output port 3 to the cylinder ports 8a and 8b to the port block 9, respectively.
[0022]
The pump ports 7a and 7b communicate with the fixed displacement pump 22 through the circuits 27a and 27b as shown in FIG. 2, and the cylinder ports 8a and 8b are similarly connected to one or the other of the hydraulic cylinders 25 through the circuits 26a and 26b. To the hydraulic oil chambers 25a and 25b.
[0023]
Solenoids 11a and 11b are attached to the proximal ends of the valve sleeves 4 of the holding valves 1a and 1b by screwing and joining the body portions 10 of the solenoids 11a and 11b so that the axes coincide with each other.
[0024]
A labyrinth groove 12 for restricting hydraulic oil leakage is provided inside the body portion 10 of the solenoids 11a and 11b screwed to the valve sleeve 4, and the proximal end side of the valve poppet 6 is slidably inserted and guided. In addition, the distal end side of the valve poppet 6 is in sliding contact with the valve sleeve 4 via a seal 13.
[0025]
Both end portions of the valve poppet 6 with the labyrinth groove 12 and the seal 13 interposed are provided with flow paths 14 and 15 that connect the input / output ports 2 and 3 to each other through the valve seat 5 between the valve sleeve 4 and the valve poppet 6. In addition to partitioning, the drain chamber 16 is partitioned by the tip portion of the valve poppet 6 and the port block 9.
[0026]
Inside the drain chamber 16, a return spring 17 is interposed between the valve poppet 6 and the port block 9, and the body portions 10 of the solenoids 11 a and 11 b are connected to the through holes 18 formed through the valve poppet 6. The valve poppet 6 communicates with the drain chamber 16 on the distal end side of the valve poppet 6 and can be pushed against the return spring 17 by a push rod 20 extending from the iron core 19 of the solenoids 11a and 11b.
[0027]
In addition, in this case, the outer diameter dimensions of both end portions of the valve seat 5 and the valve poppet 6 are made equal, and the pressure receiving areas of both portions are made equal to balance the oil pressure acting on the valve poppet 6. ing.
[0028]
Thus, the direct switching type holding valves 1a and 1b by the solenoids 11a and 11b of FIG. 1 according to the embodiment of the present invention operate as follows.
[0029]
The holding valves 1a and 1b according to the present invention configured as described above restore the return spring 17 at the tip of the valve poppet 6 through the push rod 20 when the iron core 19 receives a magnetic force by exciting the solenoid 11a or 11b. Push against the force.
[0030]
As a result, the valve seat 5 of the valve sleeve 4 that has been closed by the valve poppet 6 is opened, and from the cylinder port 8a of the port block 9 to the pump port 7a through the input / output ports 2 and 3 by the flow paths 14 and 15 of the valve sleeve 4. And the flow of pressure oil from the pump port 7b to the cylinder port 8b are allowed.
[0031]
From this, it is assumed that the solenoids 11a and 11b of the holding valves 1a and 1b, which are on the hydraulic oil suction side at that time, are selectively excited in accordance with the rotation direction of the fixed displacement pump 22 in the hydraulic drive device of FIG. .
[0032]
Then, the valve poppet 6 of the holding valve 1a or 1b on the suction side is opened by being pushed by the push rod 20 against the return spring 17, and in FIG. 2, the holding valve 1a or 1b is switched to the right position. Depending on the rotational direction of the fixed capacity pump 22 at that time, one of the hydraulic oils in the hydraulic oil chambers 25a, 25b of the hydraulic cylinder 25 is pumped up by the circuits 26a, 27a or 26b, 27b.
[0033]
Then, the pumped hydraulic oil is pumped to the circuits 26b, 27b or 26a, 27a, the valve poppet 6 of the holding valve 1b or 1a is pushed open against the return spring 17, and one hydraulic oil chamber of the hydraulic cylinder 25 is opened. Then, the hydraulic cylinder 25 is selectively operated in both forward and reverse directions.
[0034]
On the other hand, when the solenoid 11a or 11b is de-energized and switched to a non-excited state, the pressing force by the push rod 20 provided on the iron core 19 is released and the valve poppet 6 is pushed back by the restoring force of the return spring 17. .
[0035]
As a result, the valve poppet 6 is pressed against the valve seat 5 on the valve sleeve 4 side by the restoring force of the return spring 17 to close the valve seat 5 and from the cylinder ports 8a and 8b of the port block 9 to the pump ports 7a and 7b. Then, the flow of the pressure oil to be returned is cut off, and the hydraulic cylinder 25 as a load is held in the state at that time.
[0036]
In addition, in the above, the inside of the body portion 10 of the solenoids 11a and 11b in the holding valves 1a and 1b communicates with the drain chamber 16 on the opposite side through the through hole 18 that penetrates the valve poppet 6. The flow path connecting the input / output ports 2 and 3 with each other can receive pressure oil acting on both ends of the valve poppet 6 even if high pressure oil acts on one or both of them regardless of whether the valve seat 5 is opened or closed. The areas are kept equal to each other.
[0037]
Accordingly, since the oil pressure does not have any influence upon the switching operation of the valve poppet 6 by the on / off control of the solenoids 11a and 11b, the holding valves 1a and 1b are different from other types of holding valves. A large solenoid having a suction force that can overcome the hydraulic pressure acting on the valve poppet 6 of the holding valves 1a and 1b can be prevented as well as preventing hunting by itself and unnecessarily large passage pressure loss. It is possible to solve problems such as.
[0038]
In the embodiment of FIG. 1, in constructing the holding valves 1a and 1b, the valve sleeve 4 is divided into two members, that is, a proximal sleeve 4a and a distal sleeve 4a on which the valve seat 5 is formed. The base end side sleeve 4a and the front end side sleeve 4b are connected to each other by an inlay 30 while maintaining a concentric state.
[0039]
Thereby, not only can the integrity as the valve sleeve 4 be secured while maintaining the concentricity of the proximal end side and the distal end side sleeves 4a, 4b with a simple configuration, but also the valve poppet 6 is incorporated into the valve sleeve 4. Is also easier.
[0040]
Further, in this embodiment, the body portions 10 of the solenoids 11a and 11b are screwed into the inner surface of the valve sleeve 4 and are connected to the inside of these body portions 10 on the proximal end side of the valve poppet 6. Further, by directly inserting through the labyrinth groove 12, the direct switching type holding valves 1a and 1b by the solenoids 11a and 11b can be obtained with a simple configuration.
[0041]
As described above, according to the first aspect of the present invention, in the direct switching type holding valve by the solenoid , one end of the input / output port is formed by the both end portions of the valve poppet while keeping both end portions of the valve poppet oil-tight. The flow path leading from the valve seat to the other input / output port and the drain chamber located at the tip of the valve poppet and interposing the return spring , and the outer diameters at both ends of the valve seat and the valve poppet By connecting the solenoid body to the base end side of the valve sleeve and connecting the inside of the solenoid body to the drain chamber on the tip side through a hole drilled in the valve poppet, the solenoid is turned on and off. The oil pressure will no longer have any effect on the valve poppet switching operation. As a result, it is possible to eliminate the occurrence of hunting as in the case of the same type of holding valve using other types and to prevent the passage pressure loss from becoming unnecessarily large. This eliminates the need for a large solenoid with a suction force that overcomes the oil pressure acting on the poppet.
[0042]
According to the first aspect of the present invention, in constructing the holding valve, the valve sleeve is divided into two members, that is, a proximal end sleeve and a distal end sleeve in which a valve seat is formed at an end portion. By combining the tip sleeve with a concentric state with a spigot, not only can the integrity of the valve sleeve be secured while maintaining the concentricity of the proximal and distal sleeves with a simple configuration, but also manufacturing It is also easy to incorporate the valve poppet into the valve sleeve.
[0043]
Furthermore, according to the second aspect of the present invention, and fixed by inserting the solenoid on the inner surface of the valve sleeve, by inserting the proximal portion of the valve poppet into the interior of this solenoid slidably and the claims In addition to the effect of the invention of item 1, a direct switching type holding valve by a solenoid can be provided with a simple configuration.
[Brief description of the drawings]
FIG. 1 is a longitudinal front view showing an embodiment of a solenoid direct switching type holding valve according to the present invention.
FIG. 2 is a circuit diagram showing an example of use of the above holding valve.
[Explanation of symbols]
1a, 1b Holding valve 2, 3 I / O port 4 Valve sleeve 4a Base end sleeve 4b Front end sleeve 5 Valve seat 6 Valve poppet 10 Solenoid body part 11a, 11b Solenoid 12 Labyrinth groove 13 Seal 14, 15 Flow path 16 Drain Chamber 17 Return spring 18 Valve poppet hole 30 Inlay

Claims (2)

A valve poppet that slidably passes through a valve sleeve having a pair of input / output ports to contact / separate a valve seat provided on the inner surface of the valve sleeve to control the communication between the pair of input / output ports. in holding valve switchable direct you to open and close control the valve poppet by the restoring force and the driving force by the solenoid of the return spring, the two end portions of the valve poppet while maintaining the end portions of the valve poppet to oil-tight, in one The flow path leading from the input / output port through the valve seat to the other input / output port and the drain chamber located at the tip side of the valve poppet and interposing the return spring are partitioned, and both end portions of the valve seat and the valve poppet taken equal to the outer diameter of, Bode solenoid on the base end side of the valve sleeve Combine, communicates to the drain chamber of the distal end side of the body of the solenoid in through holes bored in the valve poppet, the proximal sleeve and distal side sleeve valve seat is formed at the end of the valve sleeve of two A holding valve characterized by being divided into members and configured as a single-piece valve sleeve by connecting the proximal sleeve and the distal sleeve in a concentric state with an inlay. The holding valve according to claim 1 or 2 , wherein a body portion of the solenoid is screwed and coupled to the inner surface of the valve sleeve, and a proximal end portion of the valve poppet is slidably inserted into the inside of the solenoid body portion .

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