JPH0717898Y2 - Proportional solenoid pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a proportional electromagnetic pressure control valve, and in particular, eliminates the need for air venting work to obtain a damper effect on the solenoid side, The present invention relates to a pressure control valve that can reduce

(Prior Art) A conventional example will be described with reference to FIGS.

FIG. 3 is a side view showing the proportional electromagnetic pressure control valve with a part thereof cut away, and FIG. 4 is a view taken along the line IV-IV in FIG.

An end plug 103 is attached to one end of the body 101, and a solenoid 105 is attached to the other end. The solenoid 105 is composed of a coil and a plunger slidably arranged inside the coil.

A spool 107 is slidably accommodated in the body 101, and a spring 108 is stretched between one end of the spool 107 and the end plug 103. Also, spool 107
The other end of is contacted with the plunger of the solenoid 105.

As shown in FIG. 4, the body 101 has a P port 109 connected to the hydraulic pump and a T port 1 connected to the tank.
11, C port 113 connected to the load is formed.
By sliding the spool 107 in an appropriate direction by the solenoid 105, the P port 109 and the C port 113 are connected to supply pressure oil to the load side, or the C port 11
3 and T port 111 are connected to return pressure oil to the tank.

The C port 113 communicates with an actuator (not shown) and the pilot chamber 1 formed in the end plug 103.
I am communicating with 14. The pilot chamber 114 is on the opposite side of the solenoid 105 and faces one end of the spool 107.

Now, when the solenoid 105 is excited, the spool 107 moves against the spring 108 and the P port 109 and C
Connect with port 113. At this time, a secondary pressure is generated on the C port 113 side, but this secondary pressure is also introduced to the pilot chamber 114.

Therefore, the thrust of the solenoid 105 and the acting force of the pilot chamber 114 oppose each other on the spool 107, and the spool 107 stops at a position where the forces of these two are balanced to maintain the secondary pressure at that position. Become.

By the way, in such a proportional electromagnetic pressure control valve, a so-called "hysteresis phenomenon" occurs. FIG. 5 is a diagram showing the change over time in the C port pressure, with the horizontal axis representing the current value and the vertical axis representing the pressure at the C port 113.

As shown in FIG. 5, the time change of the C port pressure is
This phenomenon is called hysteresis because it does not reciprocate on the same curve. When such a hysteresis phenomenon occurs, energy loss occurs.

Therefore, in order to reduce such a hysteresis phenomenon, so-called “dither” is added to the spool 107. This is an operation of vibrating the spool 107 with a minute amplitude.

However, when such dither is added,
On the other hand, it is possible to reduce the hysteresis, but it is more likely to vibrate than a normal pressure control valve.

Therefore, in the conventional proportional electromagnetic pressure control valve, a damper mechanism is provided to suppress the vibration of the spool 107.
That is, as shown in FIG. 3, a damper orifice 115 is installed in the body 101 to control the movement of the spool 107 to the left in the figure, and another damper orifice 117 is installed in the body 101 to set the spool in the spool. The movement of 107 to the right in the figure is suppressed.

(Problems to be Solved by the Invention) According to the above conventional configuration, there are the following problems.

In order for the damper function of the damper orifice 117 to be effective, oil and air need to be smoothly exchanged. However, the damper orifice 117
Since it is formed on the body 101, a relatively large amount of air in the solenoid 105 becomes a major obstacle.

Therefore, in order to enhance the damper effect, the solenoid 105
There is a problem that it is necessary to perform air bleeding on the side, which complicates the work and also requires the air bleeding plug 119 and the like, which complicates the configuration of the solenoid 105.

Further, in the above-mentioned conventional device, since the end of the spool 107 is directly exposed to the pilot chamber 114, the pressure receiving area is inevitably increased. The larger the pressure receiving area is, the more the thrust of the solenoid is not increased. Therefore, in this conventional pressure control valve, there is a problem that the solenoid becomes large and the power consumption increases.

The purpose of this invention is to eliminate the need for air venting,
An object of the present invention is to provide a proportional electromagnetic pressure control valve in which power consumption of a solenoid is reduced.

(Means for Solving the Problems) The present invention is directed to a body having a P port, a T port and a C port, a spool slidably accommodated in the body, and mounted adjacent to the body. A solenoid comprising a coil and a plunger slidably arranged inside the coil, the thrust of the plunger is applied to one end of the spool, and the pressure on the C port side is applied to the other end of the spool. It is premised on a proportional electromagnetic pressure control valve configured to keep the spool at a position where the acting forces on both ends of the spool are balanced.

Based on the above control valve, the present invention is directed to a first damper orifice formed in the body for restraining movement of the spool in one direction and a plunger of the solenoid for moving in the other direction of the spool. And a second damper orifice for suppressing the movement of the pilot chamber, which is slidably provided in the spool, has its outer end in contact with the body side, and has the inner end formed in the spool and communicating with the C port. It is characterized in that the spool is held at a position where the thrust of the solenoid and the acting force on the piston due to the pressure in the pilot chamber are balanced.

(Function) A second damper orifice is formed by forming a damper orifice, which is conventionally installed on the body side and which restrains the spool from moving in the other direction, in a plunger of a solenoid.

When it is formed on the body side, it is necessary to bleed the air inside the solenoid, but when it is formed on the plunger, the space volume that is the target of air bleeding is small, so such air bleeding is not possible. It is unnecessary, and the configuration of a plug or the like accompanying it is not required, and the configuration can be simplified.

When the spool moves and the P port and the C port communicate with each other, a secondary pressure is generated at the C port. This secondary pressure is
It is guided to the pilot chamber and acts on the piston. Therefore, the spool is kept at a position where the thrust of the solenoid and the acting force on the piston due to the pressure in the pilot chamber are balanced.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a side view showing a proportional electromagnetic pressure control valve with a part thereof cut away, and FIG. 2 is a view taken along the line II-II in FIG.

An end plug 3 is attached to one end of the body, and a solenoid 5 is attached to the other end. The solenoid 5 is composed of a coil 7 and a plunger 9 slidably arranged inside the coil 7.

A spool 11 is slidably accommodated in the body 1. A spring 13 is arranged on the left side of the spool 11 in the figure, and the right end of the spool 11 in the figure is the plunger 9 described above.
Is in contact with. As shown in FIG. 2, the body 1 has a P port 15 connected to the hydraulic pump, a T port 17 connected to the tank, and a C port 19 connected to the load. By sliding the spool 11 in the appropriate direction with the solenoid 5, the P port 15 and the C port
19 is connected to supply pressure oil to the load side, or
Connect C port 19 and T port 17 to return the pressure oil to the tank.

A first damper orifice 21 is formed on the body 1, and the spool 11 is formed by the first damper orifice 21.
The movement to the left in the figure is suppressed. Meanwhile, the plunger 9
A second damper orifice 23 is formed at the right end in the drawing of FIG.
The movement of 11 to the right in the figure is suppressed.

A piston 25 is slidably provided on the axis of the spool 11 as described above. The outer end of the piston 25 is brought into contact with the end plug 3 side, and the other end is in the spool 11. It faces the formed pilot room 27. This pilot room
27 is always in communication with the C port 19 through a through hole 29 and an annular groove 31 formed in the spool 11. Therefore, the secondary pressure on the C port 19 side is introduced into the pilot chamber 27.

When the pressure is introduced into the pilot chamber 27, the acting force obtained by multiplying the pressure receiving area of the piston 25 by the pressure of the pilot chamber 27 acts as a force against the thrust of the solenoid 5. Therefore, the spool 11 stops at a position where the thrust of the solenoid 5 and the acting force of the piston 25 are balanced.

Further, according to the above configuration, the first damper orifice 21
And the second damper orifice 23 exerts a damper function and suppresses the spool 11 from moving in the left-right direction.

At that time, since the second damper orifice 23 is formed at the right end of the plunger 9 and the space volume to be the target of air bleeding is small, oil and air can be smoothly exchanged, Therefore, it is not necessary to remove the air, which was required in the past, and the plug or the like required for removing the air is not needed at all.

As described above, according to this embodiment, the following effects can be obtained.

First, since the second damper orifice 23 is provided in the plunger 9 and especially at the end thereof, the oil and the air can be smoothly replaced without performing the air bleeding work.

Therefore, it is possible to eliminate the need for air bleeding, which is a complicated work.

Since the air bleeding work is no longer necessary, the air bleeding plug or the like is not needed, and the configuration of the solenoid 5 and the valve itself can be simplified.

The first damper orifice 21 and the second damper orifice
By 23, the damper function as usual is exerted.

Further, since the force against the thrust of the solenoid 5 is obtained as the acting force on the piston 25, the diameter of the piston can be freely adjusted in relation to the thrust of the solenoid. For example,
If the solenoid is downsized, the diameter of the piston 25 is reduced accordingly.

(Effect of the Invention) As described in detail above, according to the proportional electromagnetic pressure control valve of the present invention, the second damper orifice for suppressing the movement of the spool to the other side is formed in the plunger of the solenoid. The fluid can be exchanged for air without performing air removal work.

Therefore, it is possible to eliminate the need for complicated air bleeding work, and to eliminate the plugs and the like required for air bleeding work, thus simplifying the configuration.

Moreover, since the diameter of the piston can be freely adjusted in relation to the solenoid, the solenoid can be consciously downsized or its power consumption can be reduced.

[Brief description of drawings]

1 and 2 are views showing an embodiment of the present invention. FIG. 1 is a side view showing a proportional electromagnetic pressure control valve partially cut away, and FIG. 2 is II-II of FIG. Arrow view, FIGS. 3 to 5
FIG. 3 is a view showing a conventional example, FIG. 3 is a side view showing a partial cutaway of a proportional electromagnetic pressure control valve, and FIG. 4 is IV-IV of FIG.
FIG. 5 and FIG. 5 are characteristic diagrams for explaining the hysteresis phenomenon. 1 ... Body, 5 ... Solenoid, 7 ... Coil, 9 ...
… Plunger, 11 …… Spool, 21 …… First damper orifice, 23 …… Second damper orifice, 25 …… Piston, 27 …… Pilot chamber.

Claims (1)

[Scope of utility model registration request] 1. A body having a P port, a T port and a C port formed therein, a spool slidably accommodated in the body, a coil mounted inside the coil, the spool being mounted adjacent to the body. A solenoid composed of a slidably arranged plunger is provided, and the thrust of the plunger acts on one end of the spool, and the pressure on the C port side acts on the other end of the spool. In a proportional electromagnetic pressure control valve configured to keep a spool in a balanced position, a first damper orifice formed in the body for suppressing movement of the spool in one direction and a plunger for the solenoid are formed. A second damper orifice that restrains the spool from moving in the other direction, and a slidable mount provided in the spool,
A piston having an outer end in contact with the body side and an inner end facing a pilot chamber formed in the spool and communicating with the C port, and acting on the piston by thrust of the solenoid and pressure in the pilot chamber A proportional electromagnetic pressure control valve having a structure in which a spool is maintained at a position balanced with force.