JPH0542297Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a proportional electromagnetic relief valve that drives a spool valve using electromagnetic force generated by a proportional solenoid to maintain a constant circuit pressure.

[Conventional technology]

Conventionally, relief valves have mounts defined by international standards, and therefore, their bodies are also manufactured specifically for relief valves.

In addition, in the case of a proportional electromagnetic relief valve, the stability of the spool is maintained by inserting a throttle into the oil passage that communicates between the oil chambers on both sides of the spool and the groove leading to the outside.

[The problem that the idea aims to solve]

Conventional proportional electromagnetic relief valves use dedicated bodies for relief valves, but the production quantity of relief valves for hydraulic equipment is
For example, compared to a solenoid valve, there is a difference of more than 1/100, so the production method is also completely different, and there is a large difference between the unit price of a relief valve body and the unit price of a solenoid valve body, which is the biggest reason for the increase in the cost of relief valves. It was a contributing factor.

Also, the oil chamber on the proportional solenoid side of the spool is
A push rod integrated with the movable iron core of the proportional solenoid communicates with the oil chamber in the core tube on the proportional solenoid side through a loosely fitted through hole, increasing the volume of the oil chamber at the spool end.

As a result, if air remains in the core tube of a proportional solenoid that is not provided with an air vent to reduce costs, there is a risk that the stability of the spool may be impaired and vibration may occur.

Furthermore, in general, a proportional solenoid is given a dither current that produces vibrations at a relatively high frequency in order to improve its characteristics by reducing the effects of friction and sticking phenomena, so the dither vibrations act on the spool. There was also a risk that vibration would occur.

The purpose of this invention is to solve these conventional problems and provide a proportional electromagnetic relief that can prevent spool vibration at a low cost.

[Means to solve the problem]

In order to achieve the above object, the proportional electromagnetic relief valve according to this invention has a first and a second valve having a maximum diameter.
A stepped spool having a diameter of
Two grooves are provided on both sides of the spool, and two grooves that communicate with each other and lead to the tank are provided on both sides, and the spool is biased in the opening direction and slidably housed to form an oil chamber on each side of the spool. , a bush is provided between the proportional solenoid that presses the spool in the closing direction, through which the bush rod of the proportional solenoid is tightly inserted, to isolate the bush side oil chamber from the proportional solenoid oil chamber, and the oil chamber provided on both sides of the spool is The chambers are connected to the two grooves leading to the tank through oil passages, a throttle is inserted in at least the oil passage on the bush side, and of the three grooves, the first groove has the largest diameter; Pressure oil is supplied to the groove in which the stepped portion of the second diameter is formed.

In the proportional electromagnetic relief valve having the above configuration, the sliding hole and the spool are provided with a third diameter, the third diameter and the first diameter form a step part, and the valve has the step part. It is also possible to connect the groove to a tank or to external pressure via an external oil line.

The third diameter may be equal to or smaller than the second diameter.

[Function] With the above configuration, the oil chamber provided on the bush side of the spool is isolated from the oil chamber of the proportional solenoid to reduce its effective volume, and the oil chamber is connected to the tank side through the throttle. Since the spool is in communication with the spool, there is no risk that the stability of the spool will be affected by the air in the proportional solenoid.

Therefore, it becomes possible to use an inexpensive proportional solenoid that does not have an air bleed mechanism.

In addition, the grooves provided on the outer periphery of the sliding hole of the body have the same shape and arrangement as the grooves provided on the outer periphery of the sliding hole of the solenoid valve body, so it can be used in large quantities instead of an expensive body dedicated to relief valves. It is possible to repurpose an inexpensive solenoid valve body that is already produced, and only need to perform some additional machining on the sliding hole, which can significantly reduce production costs.

In addition to the above configuration, if the sliding hole and the spool are provided with a third diameter, the external oil passage communicating with the groove having a step with the first diameter will also become a parameter of the control pressure. It becomes possible to perform complex pressure control.

Note that if the third diameter is made equal to the second diameter, the pressure can be controlled by the proportional solenoid so that the pressure value is the sum of the pressure of the external oil passage.

〔Example〕

Embodiments of this invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing a first embodiment of this invention, and FIG. 5 is a longitudinal sectional view showing an example of a solenoid valve body adapted to this invention.

The bodies used in the following embodiments are all obtained by additional processing of the electromagnetic valve body shown in FIG. 5, so first, the structure of the electromagnetic valve body 1' will be briefly described with reference to FIG.

The solenoid valve body 1' has a sliding hole 3' with a diameter D ₀ that slidably accommodates a spool valve (not shown).
Three grooves 10, 11, 12 are formed in the center of the outer periphery of this sliding hole 3' in the sliding direction, and two grooves 13a, 13b are formed on both sides thereof. ，
11, 12 communicate with external oil passages 14, 15, 16, 17 directly or via an oil passage (not shown), and the two grooves 13a, 13b communicate with each other via an oil passage 13c to the outside. .

And each groove 10, 11, 12, 13
a, 13b have their widths, for example, the surfaces 10a, 13b in FIG.
It is machined as shown by 10b, and threaded portions 1a and 1b for screwing two solenoids are formed at both ends of the sliding hole 3'.

Lands 53a, 53b, 51c having a first diameter D1 are formed by machining the diameter _D0 of the sliding hole 3' of the electromagnetic valve body 1 _' having such a configuration;
Lands 53d, 53e, 5 having a second diameter _D2
A sliding hole 53 having a diameter of 3f is formed to form the body 1 shown in FIG.

Therefore, the grooves 10,1 in this body 1
1, 12, 13a, 13b and oil passages 14, 15,
16 and 17 are formed on the electromagnetic valve body 1'.

Of the grooves 10, 11, 12, 13a, 13b, the grooves 10 and 11 are connected to a hydraulic pump 40 equipped with a pressure gauge 41 via oil passages 14 and 15, and the groove 12
and 13a, 13b to oil passages 16 and 13c, 13
d, connected to the tank 42 via the oil line 17;

The spool 2 having a first diameter _D1 and a second diameter _D2 is slidably housed in the sliding hole 53, and the stepped portion 2d is housed in the groove 10. The plug 20 screwed into the threaded portion 1a on the left end side of the body 1 in the figure is inserted into the spool 2.
A spring 21 is engaged between the left end of the spool 2 and the left end of the spool 2 to bias the spool 2 to the right, i.e., in the direction of increasing the opening degree, and an oil chamber 22, which is a spring chamber, is formed on the left side of the spool 2.

On the other hand, one end of the core tube 24 of the proportional solenoid 23 including the bushing 26 is screwed onto the threaded portion 1b on the right end side of the body 1, and the bushing rod 25a integrated with the movable core 25 is tightly inserted into the bushing 26. Touch the right end and pull the spool 2
can be driven to the left against the spring 21, that is, in the direction of closing the opening.

An oil chamber 27 with a small volume is formed between the spool 2 and the bush 26, and the oil chamber 27 is isolated from the oil chamber 24a in the core tube 24 on the solenoid 23 side by the bush 26. 27 and the oil passage 13c are formed, an oil passage 2b is formed that communicates the oil chamber 22 and the oil chamber 13c, and a throttle 2c is formed in the oil passage 2a.

With the above configuration, if the input pressure acting on the groove 10 from the hydraulic pump 40 via the oil path 14 is P, the reaction force of the spring 21 is S, and the output of the proportional solenoid 23 is F, then F = π/4 (D ₁ ² −D ₂ ² )P+S, so the relationship P=F−S/π/4(D ₁ ² −D ₂ ² ) is obtained, and when the input pressure P increases and pushes the spool 2 to the right, , spool 2 and groove 13a,
10 becomes larger, the input pressure P decreases, and the spool 2 is pushed back to the left. In this way, the input pressure P is prevented from increasing beyond the set value.

In this embodiment, the oil chamber 27 provided on the proportional solenoid side of the spool 2 and the oil chamber 24a of the proportional solenoid 23 are shut off, so the effective volume of the oil chamber 27 is reduced and air remains in the core tube. Even if an inexpensive proportional solenoid is used, there is no possibility that the spool 2 will vibrate.

In addition, by reducing the effective volume of the oil chamber 27, the effect of the throttle 2c is fully exhibited, so even if a large dither current is supplied to the proportional solenoid 23, the stability of the spool is ensured, and the No vibration occurs.

Next, FIG. 2 shows a second embodiment of this invention, which is a partial modification of the first embodiment, in which land portions 63a, 63b with a diameter of D ₁ and land portions 63a, 63b with a diameter of
D ₂ land portions 63c, 63d, 63e, 63f
A throttle 61a that communicates the oil chamber 22 and the oil passage 13c is provided on the body 61 side, and the other configurations are the same as those of the first embodiment described above.

Therefore, the stepped portion 62c of the spool 62 is located within the groove 11, and the input pressure P of the hydraulic pump 40 acts within the groove 11 through the oil passage 15.

Further, FIG. 3 shows a third embodiment of this invention.

In this embodiment, the spool 72 has first and second diameters D ₁ and D ₂ , but the sliding hole 73 of the body 71
The inner diameter part 76a provided in the bush 76 and the sliding hole 7
3 lands 73c, 73d, 73e, and 73f, and the biasing force of a spring 78 that biases the spool 72 in the opening direction can be adjusted by an adjustment screw 79.

Therefore, the sliding hole 7 in which the spool 72 slides
3 lands are only lands 73c and 73d,
Since the lands 73e and 73f do not function as sliding holes, when processing the body 71, the lands 73e and 73f are used as sliding holes 3' with a diameter D ₀ of the solenoid valve 1'.
You can leave it as is. Note that in this embodiment, the oil passage 15 is not involved in any function.

Furthermore, FIG. 4 shows a fourth embodiment of this invention, which is a partial modification of the third embodiment described above.
Sliding portion 86 having a third diameter D ₃ on the bush 86
a, and correspondingly, the spool 82 has a first,
Second and third diameters D ₁ , D ₂ , and D ₃ are provided.

In this embodiment, when the third diameter D ₃ is made equal to the second diameter D ₂ , pressure control is performed by the proportional solenoid 23 so that the pressure value is the sum of the pressure in the oil passage 15 .

Furthermore, if the third diameter D ₃ is made smaller than the second diameter D ₂ , the pressure of the oil passage 15 is Pc, π/4(D ₁ ² −D ₂ ² )P+S=π/4(D ₁ ² − D ₃ ² ) Pc+F P=F+π/4(D ₁ ² −D ₃ ² )Pc−S/π/4(D ₁ ²
−D ₂ ² ).

[Effect of idea]

As mentioned above, according to this invention, the oil chamber provided on the proportional solenoid side of the spool and the oil chamber of the proportional solenoid are completely shut off, making it possible to reduce the effective volume of the oil chamber at the end of the spool. .

Since a throttle is inserted at least into the oil passage that connects the oil chamber at the end of the spool to the tank side, even if air remains in the core tube of the proportional solenoid, it will not be affected by it, and the air bleed mechanism will not be affected. It becomes possible to use inexpensive proportional solenoids that do not have

In addition, the groove provided on the outer periphery of the sliding hole of the body has the same shape and arrangement as the solenoid valve body, so instead of using an expensive body dedicated to relief valves, an inexpensive solenoid valve body can be used to Only additional processing is required, and the production cost of the proportional electromagnetic relief valve can be significantly reduced.

Furthermore, in addition to the above configuration, if the sliding hole and the spool are provided with a third diameter, the external oil passage communicating with the groove having a step with the first diameter also becomes a parameter of the control pressure. Therefore, it becomes possible to perform complex pressure control.

Note that if the third diameter is made equal to the second diameter, the pressure can be controlled by the proportional solenoid so that the pressure value is the sum of the pressure of the external oil passage.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view showing a first embodiment of this invention, Fig. 2 is a longitudinal sectional view showing a second embodiment of this invention, and Fig. 3 is a longitudinal sectional view showing a third embodiment of this invention. 4 is a longitudinal sectional view showing a fourth embodiment of this invention, and FIG. 5 is a longitudinal sectional view showing an example of a solenoid valve body adapted to this invention. 1,61,71...Body, 1'...Solenoid valve body, 2,62,72,82...Spool, 1
0, 11, 12, 13a, 13b...groove, 22...
...Oil chamber at the end of the spool, 23...Proportional solenoid,
24... Core tube, 25... Movable iron core, 25
a... Bush rod, 26, 76, 86... Bush, 27... Oil chamber at the end of the spool, 40... Hydraulic pump, 42... Tank, D ₁ ... First diameter,
D ₂ ... second diameter, D ₃ ... third diameter.

Claims (1)

[Claims for Utility Model Registration] 1. A step spool having a first diameter and a second diameter having a maximum diameter, and a sliding hole formed in the corresponding body at the center in the sliding direction, respectively Three grooves communicating with the oil passage leading to the tank are provided, and two grooves are provided on both sides of the grooves that communicate with each other internally and communicate with the tank, and the spool is biased in the opening direction and slidably housed. an oil chamber is formed on each side of the spool, and a push is provided between the proportional solenoid that presses the spool in the closing direction, through which the push rod of the proportional solenoid is tightly inserted, so that the push side oil chamber and the proportional solenoid are The oil chambers provided on both sides of the spool are communicated with the two grooves leading to the tank via oil passages, and a throttle is inserted into at least the oil passage on the pusher side. The first groove with the largest diameter
A proportional electromagnetic relief valve characterized in that pressure oil is supplied to a groove in which a step portion having a second diameter is formed. 2 A third diameter is provided in the spool, a step is formed between the third diameter and the first diameter, and the groove having the step is connected to a tank or external pressure via an external oil path. The proportional electromagnetic relief valve according to claim 1. 3. The proportional electromagnetic relief valve according to claim 2, wherein the third diameter is equal to the second diameter. 4 Claim 2 in which the third diameter is smaller than the second diameter
Proportional solenoid relief valve as described.