JPH0442624Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a spool stroke limiting mechanism, more specifically, a stroke limiting mechanism for controlling the flow rate at the end of the stroke by adjusting the stroke of the spool of a control valve from the outside. It is about the mechanism.

[Conventional technology and its technical issues]

Spool-type control valves are commonly used as means for controlling the operation of hydraulic actuators in construction machinery. This control valve generally has a bolt fixed to the spool end protruding from the valve body to maintain the neutral position, two spring seats are engaged with the bottle and the spool end, and a spring is interposed between them. There are 3 strokes: push and pull.
The "push" and "pull" strokes are equivalent.

By the way, depending on the use of the actuator,
You may want to limit the maximum movement speed. As a countermeasure against this problem, there is a throttle check system in which a throttle is interposed in the return path of the hydraulic circuit, but this method has problems in that the circuit configuration becomes complicated and expensive, and it cannot be freely adjusted from the outside.

Therefore, a stroke limiting mechanism as shown in FIG. 2 is conventionally known. In this mechanism, a spring seat 6 is locked to the inner end surface 30' of the head of a bolt 3' fixed to the spool 2, and an adjustment screw 12 is screwed into the end of a cap 4' that supports the spring seat 6. has been done. In this mechanism,
The distance between the outer end surface of the bolt 3' and the adjusting screw 12 changes depending on the screwing amount of the adjusting screw 12, and the stroke _s1 is more limited than the normal stroke S.

However, although this prior art allows stroke adjustment from the outside, it can only restrict the stroke on the push side, that is, the passage area that changes with the spool push stroke. Therefore, regardless of whether the actuator is a hydraulic cylinder or the like, when the actuator is a hydraulic motor, there is a problem in that the rotational speed can only be adjusted in either the clockwise or counterclockwise direction.

This invention was devised to solve the above-mentioned problems, and its purpose is to:
It is an object of the present invention to provide a spool stroke limiting mechanism of this type in which both the "push" and "pull" strokes can be adjusted independently and continuously from the outside.

[Means to solve the problem]

In order to achieve the above object, the present invention is such that the inner end surface (lower neck side) and outer end surface of the bolt head act as a stopper that limits the pulling and pushing strokes of the spool. It has a bolt fixed to the end, two spring seats locked to the bolt and the spool end, a spring interposed between the spring seats, and a cap having a supporting surface for one of the spring seats. In the mechanism for maintaining the neutral position of the spool and setting the normal stroke, the bottle has a head via a step for locking the spring seat and a shaft extending rearward from the step, and the cap has the head. A first stroke adjustment screw having a cylindrical shape and having an abutting portion for the inner end surface of the head is screwed into the first stroke adjustment screw, and a second stroke adjustment screw facing the outer end surface of the head is screwed into the first stroke adjustment screw. It has a structure that is

[Effect]

In order to regulate the pulling stroke, it is sufficient to rotate the first stroke adjusting screw, which changes the distance between the inner end surface of the bottle head and the abutting part of the first stroke adjusting screw, and the spool's normal The pull stroke is regulated to be shorter than the stroke. In addition, in order to regulate the pushing stroke, it is sufficient to rotate the second stroke adjusting screw that is screwed into the first stroke adjusting screw, and this allows the tip of the second stroke adjusting screw to The distance between the end faces changes and the pushing stroke is regulated to be shorter than the normal stroke of the spool. All of these can be freely operated from the outside.

〔Example〕

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

FIG. 1 shows a spool stroke limiting mechanism according to the present invention, in which 1 is a valve body, 2 is a spool slidably inserted into the valve body 1, and a seal ring 14 is held at the end of the valve body by an end plate 13. The valve body is sealed with oil, and the part beyond that protrudes outside the valve body.

3 is a bolt fixed coaxially to the end of the spool 2, and 4 is a cap that concentrically surrounds the bolt 3 and the spool 2. The cap 4 is fixed to the end plate 13 by screws or the like, and is provided with an inner flange 4a at an axially intermediate portion.

The bolt 3 is attached to the shaft portion 3a before the fixed end of the spool.
and the shaft portion 3a via the step portion 3b.
A shaft portion 3c having a larger diameter is formed, and this shaft portion 3c extends rearward through the inner flange 4a,
A head 3d is formed at the end branch.

Reference numerals 5 and 6 denote spring seats, and one spring seat 5 has an inner flange 5a and is locked to the spool end face 2a, so that they move together when the spool 2 is moved (pushed) to the right.
The other spring seat 6 has an inner flange 6a and is locked to the stepped portion 3b, and is adapted to move together with the spool 2 by moving (pulling) it to the left.
A normal stroke S is set by the distance between the inner flanges of the spring seats 5 and 6.

7 is a first stroke adjustment screw;
It has a cylindrical shape with an inner diameter larger than the head 3d of the bolt 3, and a ring-shaped abutment part 7a for the inner end surface 30 of the head of the bottle 3 is formed at the tip. 3c is allowed to freely slide on the contact portion 7a. Further, a male thread 7b is formed on the outer periphery of the first stroke adjustment screw 7 over a required length from the tip, and this male thread 7b is screwed into the cap through a screw hole 4b provided in the end wall of the cap 4. A fixing nut 9 is screwed into the external threaded portion of the cap. Furthermore, the first
There is a flange-like operating portion 7d for rotating the stroke adjustment screw.

8 is a second stroke adjustment screw;
It has a contact part 8b for the head outer end surface 31 of the bolt 3 at the tip, and a male thread 8a on the outer periphery.
It is screwed into a threaded portion 7c formed over a required length from the opening of the first stroke adjustment screw 7. A fixing nut 11 whose stopper is the collar-like operating portion 7d of the first stroke adjusting screw 7 is screwed onto the male thread 8a.

[Effect of the embodiment]

In FIG. 1, when the fixing nut 9 is loosened and the flange-like operating portion 7d is rotated using a tool such as a spanner, the first stroke adjustment screw 7 is moved in the axial direction of the cap 4 in relation to the female threaded hole 4b. As a result, the distance between the inner end surface 30 of the head of the bolt 3 and the contact portion 7a changes continuously. Therefore, if the spool 2 is pulled while rotating the flange-like operating portion 7d, the passage area changes with the stroke, and the flow rate is adjusted. When the desired flow rate is reached, the first stroke adjustment screw 7
If the rotation of the spool 2 is stopped and the fixing nut 9 is tightened until it touches the outer wall of the cap 4, the stroke of the spool 2 will be a pulling stroke shorter than the normal stroke S.
regulated by s ₁ .

Further, when the fixing nut 11 is loosened and the push adjustment screw 8 is rotated, the push adjustment screw 8 is moved in the axial direction with respect to the first stroke adjustment screw 7 in relation to the female thread 7c, and the head of the bolt 3 is moved. The distance between the outer end surface 31 and the contact portion 8b changes continuously. Therefore, by operating the spool 2 while rotating the second stroke adjustment screw 8 and tightening the fixing nut 11 at any point until it abuts against the flange-like operating portion 7d, a pushing stroke shorter than the normal stroke S can be achieved. regulated by s ₂ .

The above-mentioned pull and push stroke adjustments can be made externally and independently using each adjustment screw, so for example, the pull stroke can be adjusted to 6.5 mm,
The pushing stroke can be set to a different value such as 6.0 mm. Therefore, if the actuator is a hydraulic motor, the stroke can be freely regulated in any direction and appropriate rotational speed adjustment can be achieved. Further, the speed of the control valve is generally regulated by providing a notch in the spool, but the tolerance of this notch differs slightly for each valve, and this appears as variations in the speed of the actuator. In such a case, according to the present invention, matching can be easily performed from the outside by performing the above operations while the device is mounted on an actual machine.

[Effect of idea]

According to the present invention described above, a bolt fixed to the spool end, two spring seats locked to the bolt and the spool end, and a spring interposed between the spring seats,
The mechanism has a cap with a surface that supports one spring seat, and maintains the neutral position of the spool and sets the normal stroke. Either the "push" or "pull" stroke can be controlled independently from the outside. It can be adjusted continuously, which means that when a hydraulic motor is used as the actuator, the rotation speed can be adjusted in either the clockwise or counterclockwise direction, and the structure is simple. You can get the same effect.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a spool stroke limiting mechanism according to the present invention, and FIG. 2 is a sectional view showing a conventional stroke limiting mechanism. 2...Spool, 3...Bolt, 3b...Step, 3c...Shaft, 3d...Head, 4...Cap, 5, 6...Spring seat, 7...First stroke adjustment screw , 7a... contact portion, 7
b...Male thread, 7c...Female thread, 8...Second stroke adjustment screw, 30...Inner end surface of head,
31... Outer end surface of the head.

Claims (1)

[Scope of utility model registration request] A bolt fixed to the spool end, two spring seats locked to the bolt and the spool end, a spring interposed between the spring seats, and a cap with a surface supporting one of the spring seats. In the mechanism for maintaining the neutral position of the spool and setting the normal stroke, the bolt has a head via a stepped portion for locking the spring seat and a shaft portion extending rearward from the stepped portion, and the cap includes: A cylindrical first stroke adjustment screw having an abutting portion for the inner end surface of the head is screwed into the first stroke adjustment screw, and a second stroke adjustment screw facing the outer end surface of the head is screwed into the first stroke adjustment screw. A spool stroke limiting mechanism characterized by: