JPS626321Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a direction/flow control valve, and more specifically, it controls the operation of a driving cylinder of a heavy object transport vehicle to smoothly move a heavy object as a load. This invention relates to a direction/flow rate control valve used for acceleration/deceleration control of a cylinder, such as when moving the cylinder to a position and stopping it at an accurate position.

[Prior art] In general, cylinder speed control for moving heavy loads uses a direction/flow control valve with a meter-out connection to prevent the cylinder from moving by itself due to the inertial force of the load, especially during deceleration control. This method ensures that the load deceleration always accurately follows the electrical input to the proportional solenoid directional/flow control valve.

By the way, even in meter-out control, direction and
It is known that when the flow rate control valve is in its neutral state, if there is a leak inside the valve from the pressure port P to the cylinders A and B ports, the one-rod cylinder will gradually move, causing a so-called neutral micro-movement phenomenon.
To prevent this neutral movement, the valve configuration should be so-called open center, where the A and B ports are connected to the R port returning to the tank when in neutral.
An ABR connection may be used, and in this way, leakage from the P port to the A and B ports will flow to the R port in the neutral state, so that slight movement of the cylinder in the neutral state will not occur.

Conventionally used proportional electromagnetic directional/flow control valves have inching on their spools to achieve a so-called ABR connection by creating an underlapping state when in neutral. However, with this method, the spool does not move from the neutral position during meter-out control. As the actuator slides into the control position, the opening area of the actual variable diaphragm that controls the exhaust flow from the actuator increases. In other words, when another throttle located at a position that controls the inflow flow from the P port to the actuator attempts to open in the forward direction, the original discharge throttle already maintains a certain opening area, so the spool When the sliding movement is small, meter-in control is used to control the inflow flow to the actuator by the other throttle, and the spool slides further and the opening area of the original discharge throttle becomes smaller than the opening of the other throttle on the inflow side. When it becomes smaller than the area, meter-out control is performed for the first time. Therefore, there is a drawback that meter-out control cannot be performed at minute flow rates, making it difficult to accurately control the speed of the actuator.

In addition, even if a pressure compensation valve is attached to the conventional direction/flow control valve that connects to ABR when in neutral mode as described above, and the pressure difference before and after the discharge restriction is to be controlled at a constant level regardless of the load pressure, the spool During minute flow rate control with small sliding movement, as mentioned above, the opening area of the discharge throttle is larger than that of the inflow throttle, so there is almost no pressure difference before and after the discharge throttle, and the pressure compensation valve presses the pressure compensation valve spool with a spring. However, the pressure compensation function does not work. Therefore, in such a case, in order to obtain a pressure compensation effect even at a minute flow rate, it is necessary to configure the valve so that it is closed center when in neutral, and the reality is that the request for ABR connection could not be met. It is.

[Problems that the idea should solve]

The present invention was made to eliminate these drawbacks of the conventional technology, and it makes the direction/flow control valve for meter-out control connect to ABR when it is in neutral, and also enables accurate meter-out control even at minute flow rates. The purpose of this invention is to make it possible to realize this, and to also enable the pressure compensation function to work effectively even at minute flow rates even when pressure compensation is provided.

[Means for solving problems]

That is, in order to achieve the above-mentioned purpose, the direction/flow control valve of the present invention has a P port connected to the pressure supply flow path, an A port and a B port connected to the actuator, and a return flow path. the R port, a closed center type meter-out control direction/flow rate control valve element a main valve spool that moves in response to pilot pressure, and a main valve spring that maintains the main valve spool in a neutral state when there is no pilot pressure and generates a counterbalancing spring force when pilot pressure is applied; The main valve spool also has ports A and B connected to ports P and R in the neutral state.
When the main valve spool is displaced to one side against the main valve spring due to the action of pilot pressure on one end, the throttle control opening is adjusted according to the position of the valve spring. The B port and R port are communicated, and the A port and P port are communicated with each other at a larger opening degree, and the main valve spool resists the main valve spring by the action of pilot pressure on the other end. a plurality of opening/closing and throttle control units that communicate the A port and the R port with a throttle control opening degree corresponding to the amount of displacement when the valve is displaced in the other direction, and communicate the B port and the P port with a larger opening degree; The switching valve element Y further includes a switching valve spool that selectively moves at both ends in response to pilot pressure at the same time as the main valve spool, and a switching valve spool that maintains the switching valve spool in a neutral state when there is no pilot pressure. and another spring having a spring constant selected to move the switching valve spool to the switching position while the main valve spool moves through the overlap portion when pilot pressure is applied;
Furthermore, the switching valve spool is configured such that both the A and B ports communicate with the R port outside the control valve element X in the neutral state, and the switching valve spool receives the pilot pressure acting on the main valve spool. When moved to the switching position against the another spring, the communication between the A port, the B port, and the R port is cut off from the outside, and an independent valve chamber is formed, and the switching valve spool is moved in a direction corresponding to the moving direction of the switching valve spool. When pilot pressure acts on one end of the main valve spool, the B port is communicated with the valve chamber, and when pilot pressure acts on the other end of the main valve spool, the A port is communicated with the valve chamber. It is formed by forming a plurality of switching control sections.

[Effect]

In the present invention, the direction/flow rate control valve element that exclusively performs meter-out flow control is responsible for blocking the P port in neutral, and the ABR connection in neutral is carried out by the separately combined 3-position switching valve element. This 3-position switching valve element ensures the independence of the A, B, and R ports in the flow control state, so the P port and A, B ports of the direction/flow control valve element are Although it has a structure that blocks the P port in neutral by forming an overlap between the spool and the valve body, it is possible to achieve ABR connection in neutral, and when the flow rate control state is entered, this external ABR connection is established. is disconnected, and the direction/flow control valve element becomes similar to a closed center spool, thus enabling accurate meter-out control at minute flow rates by controlling the meter-out control opening from zero. .

In the present invention, an independent valve chamber is also formed which communicates with the A port or the B port which receives pressure oil discharge from the actuator when the direction/flow control valve element enters the flow control state. Therefore, the pressure in the valve chamber and the pressure in the R port can be applied to the pressure compensating valve as the pressure before and after throttling, so that the oil flow in the R port can be compensated and controlled.

〔Example〕

Next, an embodiment of this invention will be described with reference to the drawings. Fig. 1 shows an example of a proportional electromagnetic type direction/flow rate control valve without a pressure compensation function, and shows a direction/flow rate control valve incorporated in the valve body 1. The control valve element X and the small valve element Y of the spring center 3-position switching valve incorporated in the small valve body 5 are integrally connected. First, regarding the control valve element The oil return passage 17 is connected to the return passage to the tank 22. A main valve spool 2 is slidably built into the valve body 1, and both end surfaces 1 of the main valve spool 2 are slidably movable.
8 and 18' are biased by the force of main valve springs 3 and 3' disposed in main valve spring chambers 19 and 19', respectively, thereby providing a spring center system. The pilot pressure of proportional electromagnetic pilot relief valves 8, 8' controlled by solenoids 4, 4' is applied to both end faces of the main valve spool, and the main valve spool and the valve body on which it slides are applied. A first variable throttle 14, 14' connected to the P port and a second variable throttle 15, 15' connected to the R port are formed between the openings of the valve hole to the A and B ports. It is set as. The main valve spool is a closed center when in neutral, and the first variable throttle 14, 14' directs the inflow flow to the actuator 16 through the second variable throttle 1.
5 and 15' are for controlling the discharge flow, respectively.
When they are in neutral, they are in an overlapping state and the opening area is zero, and when the main valve spool 2 slides until it is in equilibrium with the spring force of the main valve spring due to the increase in pilot pressure and becomes oriented, the first variable throttle 14 ，
The opening area of 14' is larger than the opening area of second variable throttle 15, 15', and the direction and flow rate of the pressure oil flow are controlled by meter-out control. Next, the small valve element Y is a spring center type 3 valve that connects the A and B ports of the control valve element The position switching valve is equipped with a small valve spool 6 that is slidably disposed within the small valve main body, and both end surfaces 9 and 9' of the small valve spool 6 are connected to small valve spring chambers 10 and 1.
A spring center system is employed in which small valve springs 7 and 7' having a relatively weak spring force are respectively biased within the center of the valve.

The small valve spring chambers 10, 10' are the main valve spring chambers 19, 1 at both ends of the main valve spool 2 of the control valve element.
9', so that the pilot pressure of the pilot relief valves 8, 8' acts also on both end surfaces of the small valve spool. Reference numeral 23 denotes a valve chamber formed by the central small diameter portion of the small valve spool 6, which receives pressure oil discharge from the actuator 16 when the main valve spool 2 slides and enters the flow rate control state. It is an independent chamber that communicates with actuator port A or B and into which the pressure before the meter-out throttle control section is introduced.

In the direction/flow rate control valve of the embodiment shown in FIG. 1 described above, when the pilot pressure in the proportional electromagnetic pilot relief valve 8 is first increased by an external electric signal, the pilot pressure is also applied to the small valve spool end face 9. Since the small valve spool end face 9'
The small valve spool moves to the left in FIG. 1 against the weak spring force of the small valve spring 7', cutting off the communication between the A, B and R ports of the small valve element Y, and the pilot pressure further increases. Then, the main valve spool 2 of the control valve As the flow passes through, the first variable throttle 14' opens further and the opening area of the second variable throttle 15 gradually begins to open from zero, so that meter-out control can be performed from an extremely small flow rate. At this time, since the switching of the small valve spool 6 is performed in the overlapping portion of the main valve spool 2, that is, in the dead zone, the controllability of the main valve is not impaired. Also,
Even when the main valve spool 2 returns to the neutral position, the main valve spool 2 returns to the neutral position and the pilot pressure in the small valve spring chamber 10 is sufficiently reduced before the small valve spool 6 moves to release the weak small valve spring. A spring force of 7' causes the control valve element X to return to its neutral position.
after the small valve element Y closes each of its ports.
Achieve ABR connectivity.

Next, another embodiment of this invention will be described. The one shown in FIGS. 2 and 3 is the integrally coupled direction/flow rate control valve element X and spring center 3 position small according to the embodiment shown in FIG. A pressure compensating valve element Z is attached to the valve element Y, and regardless of fluctuations in the load pressure at the R port of the control valve element The control flow rate is compensated by maintaining the flow rate at a constant value. Needless to say, in this case as well, the ABR connection is achieved by the small valve element Y when the main valve spool 2 is in the neutral state. The pressure compensating valve element Z has a compensating valve spool 11 slidably built into its compensating valve body 21, and the spool 11
One end face is elastically biased by a compensation valve spring 12 disposed in a compensation valve spring chamber 13, and a compensation valve pressure chamber 20 is formed between the other end face and the main body 21. This pressure chamber 20 is connected to the valve chamber 23 of the small valve element Y, so that the pressure before the meter-out throttle control section of the control valve element X is introduced into the pressure chamber 20. Oil return path 17 of control valve element X
The R port of the small valve element Y communicates with the compensation valve spring chamber 13, and is also connected to the tank 22 from the R' port via a pressure compensation control section 24 by the compensation valve spool 11.

In such a configuration, when the main valve spool 2 is in neutral, the pressure chamber 20 is communicated with the R port via the small valve element Y, and in this case, the compensation valve spool 11 is opened by the force of the compensation valve spring 12. Located in
Therefore, the oil return path 17 of the control valve element
is open to the public. The pilot pressure rises and the small valve spool 6 operates in the dead zone of the control valve element X, as in the previous embodiment, but when the first and second variable throttles begin to open, the control valve spool 6 operates in the dead zone of the control valve element X. The small valve element Y now has the function of selectively guiding the pressure of the A port or B port to the compensation valve pressure chamber 20 of the compensation valve element Z, and this selection energizes the solenoid 4 of the proportional pilot relief valve 8. At this time, the pilot pressure acts on the small valve spool end face 9 to guide the pressure at the B port to the compensation valve spring chamber 20, and the compensation valve spool 11 of the compensation valve element Z connects the oil path to the R port of the control valve element It is displaced until it is balanced by the pressure in the compensation valve spring chamber 13 into which the pressure of the oil passage is introduced, and the spring force of the compensation valve spring 12, and the valve is displaced before and after the second variable throttle 15 formed adjacent to the B port. The pressure difference will be kept constant. Furthermore, when the solenoid 4' of the proportional pilot relief valve 8' is energized, the small valve element Y introduces the pressure of the A port into the compensation valve pressure chamber 20 of the compensation valve element Z, and its operation is in accordance with the above explanation. Therefore, I will not elaborate further.

[Effect of idea]

As described above, according to the present invention, by simply combining the small valve elements of a spring center type three-position switching valve, the direction and direction for meter-out control can be adjusted.
The flow control valve can be connected to ABR when in neutral, and the discharge restrictor can be controlled accurately from zero opening, and accurate meter-out control can be performed even at minute flow rates. The present invention provides a direction/flow rate control valve that can prevent slight neutral movement of an actuator such as a single-rod cylinder due to leakage.

In addition, in the above two embodiments, the pilot pressure was controlled using a proportional electromagnetic pilot relief valve driven by an electric signal, and each spool was slid. Needless to say, similar effects can be obtained by controlling the pilot pressure using an electromagnetic pressure reducing valve or a nozzle flapper.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view showing an embodiment of this invention, Fig. 2 is a longitudinal side view showing another embodiment, and Fig. 3 is an explanation of the small valve elements in the previous figure expressed with hydraulic symbols. It is a diagram. X...Direction/flow rate control valve element, Y...Spring center 3 position small valve element, Z...Pressure compensation valve element, 2...Main valve spool, 3, 3'...Main valve spring, 4, 4' ...Solenoid, 6...Small valve spool, 7,7'...Small valve spring, 8,8'...Proportional electromagnetic pilot relief valve, 9,9'...Small valve spool end face, 10,10'... ...Small valve spring chamber, 11...
...Compensation valve spool, 12...Compensation valve spring, 13...
... Compensation valve spring chamber, 14, 14'... First variable throttle, 15, 15'... Second variable throttle, 16... Actuator, 17... Oil return path, 18, 18'...
...Valve spool end face, 19, 19'...Control valve spring chamber, 20...Compensation valve pressure chamber.

Claims (1)

[Claims for Utility Model Registration] P port connected to the pressure supply flow path, A port and B port connected to the actuator, R port connected to the return flow path, and a closed center meter-out The control valve element X includes a control direction/flow rate control valve element X and a spring center type three-position switching valve element Y, and the control valve element X has a main valve spool at both ends that moves selectively under pilot pressure; A main valve spring is provided that maintains the main valve spool in a neutral state when there is no pilot pressure and generates a counterbalancing spring force when pilot pressure is applied, and the main valve spool has the above-mentioned A and A in the neutral state. The B port is blocked with respect to the P and R ports through overlapped portions, and when the main valve spool is displaced to one side against the main valve spring due to the action of pilot pressure on one end, the amount of displacement is communicating the B port and R port with a corresponding throttle control opening degree, and communicating the A port and P port with a larger opening degree;
When the main valve spool is displaced to the other side against the main valve spring due to the action of pilot pressure on the other end, the A port and R
A plurality of opening/closing and throttling control parts are formed to communicate with the port and to communicate the B port and the P port with a larger opening degree, and the switching valve element Y has both ends at the same time as the main valve spool. a switching valve spool that selectively moves in response to pilot pressure; and a switching valve spool that maintains the switching valve spool in a neutral state when there is no pilot pressure and while the main valve spool moves through the overlap portion when pilot pressure is applied. another spring is provided with a spring constant selected to move the switching valve spool to the switching position, the switching valve spool being provided with a spring which, in a neutral state, connects the A and B ports together outside of the control valve element X; When the switching valve spool receives the pilot pressure acting on the main valve spool and moves to the switching position against the another spring, the external connection between the A port, the B port, and the R port is communicated with the R port. cutting off communication at the valve chamber and forming an independent valve chamber, and communicating the B port with the valve chamber when pilot pressure acts on one end of the main valve spool depending on the direction of movement of the switching valve spool;
A direction/flow rate control valve characterized in that a plurality of switching control parts are formed to communicate the A port with the valve chamber when pilot pressure acts on the other end of the main valve spool.