JPH04102733A - Dashpot - Google Patents

Abstract

PURPOSE:To obtain a dashpot which has a small diameter and the stable operation characteristic and for which restriction for installation place is little, by forming a communication passage for the communication between the first chamber and a valve chamber, throttle passage, and installing a valve body for closing the communication passage when a piston shifts toward the second chamber, in the valve chamber. CONSTITUTION:When the controlled equipment contacts a cap 11, and retreats a piston rod 14, the first chamber 21 is expanded, and the second chamber 22 is contracted, and the internal pressure is increased, and a valve body 35 closes a communication passage 32, and the fluid in the second chamber 22 is introduced little by little into the first chamber 21 from a valve chamber 34 through a throttle passage 33 and the communication passage 32, and the operation speed of the controlled equipment is reduced. When the controlled equipment is separated, a piston 23 and a piston rod 4 are advanced by the spring load of a return spring 38, and the first chamber 21 is contracted, and the internal pressure is increased, and a valve body 35 opens the communication passage 32, and the fluid in the first chamber 21 is transferred free from resistance into the second chamber 22 from the valve chamber 34, and the piston rod 4 is returned to an inoperative position.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dashpot used to reduce the operating speed of controlled equipment and prevent sudden changes in force or position.

(Prior art) There are two types of dashpots: pneumatic and liquid type. It is well known that a diaphragm is generally used as a shock absorbing member for a controlled device, and a diaphragm or a piston is used for a liquid type.

Among these, the pneumatic type is, for example,
As disclosed in Publication No. 9 and Japanese Patent Publication No. 59-30898, it is widely used for stabilizing the closing speed of intake throttle valves in automobile engines because it uses atmospheric air and can be easily installed. It is unavoidable that the diameter is large, and if the stroke is increased, the diameter becomes even larger, which not only limits the installation location, but also has the disadvantage that the initial distortion of the diaphragm causes large variations in the starting point of operation. be.

On the other hand, pneumatic and liquid type piston-type valves have a smaller diameter than a diaphragm, but because the check valve is provided on the piston or outside the cylinder, the overall size cannot be made sufficiently small.

(Problems to be Solved by the Invention) The problems to be solved by the present invention are that conventional dashpots are quite large, have restrictions on installation locations, have unstable operating characteristics, and tend to lack reliability. be.

That is, the present invention is a dashpot with a compact configuration that is small in diameter, is less subject to restrictions in installation location, and has stable operating characteristics. It was designed to be more compact.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a cylinder tube having a partition wall that divides the interior into two spaces, front and rear, and a cylinder tube that extends vertically through the front space and penetrates the partition wall. A piston rod inserted into the space, a piston attached to the piston rod and dividing the rear space into a first chamber on the partition wall side and a second chamber on the opposite side, and pushing the piston toward the partition wall. a return spring; a piston retainer fitted to the piston rod so as to overlap with the second chamber side of the piston; a valve chamber surrounded by the piston rod and the piston retainer and communicating with the second chamber through a fluid inlet/outlet; The piston is provided with a communication passage and a throttle passage that communicate the first chamber and the valve chamber, and a valve body that is inserted into the valve chamber and closes the communication passage when the piston moves toward the second chamber. .

In addition, the piston retainer is made of synthetic resin, a metal sleeve is fixed to the inner circumferential surface of the tip, and this sleeve is press-fitted into the piston rod.The throttle passage is branched from the communication path and extends to the outer circumferential surface of the piston rod. It is preferable to have a configuration in which the valve chamber is communicated with the valve chamber by opening.

(Operation) In the non-operating state, the piston is pushed back by the spring to a position where movement is prevented by the partition wall, and the starting point of operation is kept constant. When the controlled device pushes the piston rod, the valve body closes the communication passage and opens the second chamber.

The operating speed is reduced by restricting the movement of fluid from the valve chamber to the first chamber.

(Example) The present invention will be described in detail with reference to the drawings.

The cylinder has a central partition wall 2, which divides the interior into two front and rear spaces, and a cylinder tube 1 with both ends open. A piston rod 4 is inserted through the through hole 3, and this piston rod 4 is fitted into a guide hole 6 of a guide member 5 fixed to the open end, and is reciprocated in a straight line by the through hole 3 and the guide hole 6. supported to move.

The guide member 5 is made of hard synthetic resin, and includes a flange portion 7 that is fitted into the stepped portion 1m at the end of the cylinder tube 1 and fixed by an outer caulking portion 1b, and a collar portion 8 that extends outward. It has

Further, a small diameter portion 9 having an annular groove 10 is formed at the tip of the piston rod 4 protruding from the cylinder tube 1, and a hard synthetic resin cap 1 having a larger diameter than the piston rod 4 is formed.
1 is engaged with the annular groove 10 and attached to the small diameter portion 9, and the protruding portion of the piston rod 4 is a bellows whose both ends are fitted and fixed to the tip of the piston rod 4 and the small diameter portion 8a of the collar portion 8. It is covered by a dust cover 12 of the shape.

In the space in front of the cylinder tube 1, that is, the inside between the partition wall 2 and the guide member 5, a backing chamber 13 with a small diameter on the partition wall 2 side is formed by a stepped portion 1c. The collar portion 16 of the spring receiver 16, which is loosely fitted to the piston rod 4, is inserted and is slightly separated from the end surface of the backing 14. The flange portion 17 of the spring receiver 15 is located at the large diameter portion on the guide member δ side, and is moved in the direction of contact with the step portion 1c by a compression spring 18 made of a compression coil spring inserted between the flange portion 7 of the guide member 5 and the flange portion 17 of the spring receiver 15. receives the power of

The rear open end of the cylinder tube 1 is hermetically sealed by a plug 20 having an O-ring 19 that engages with the stepped portion 1d and is pressed and fixed by the outer caulking portion 1e. The space behind the cylinder tube 1, that is, the partition wall 2 and the plug 20
The inside between the two has a uniform diameter, and is partitioned into a first chamber 21 on the partition wall 2 side and a second chamber 22 on the plug 20 side by a piston 23 attached to a piston rod 4 protruding from this part.

That is, a retaining ring 24 is attached and fixed to a portion of the piston rod 4 that protrudes from the partition wall 2 to the rear space, and a bowl-shaped piston stopper 26, a piston 23, and a piston retainer 26 are sequentially attached to the piston rod 4 on the tip side thereof. It is fitted. The piston 23 is made of synthetic rubber, synthetic resin, or leather;
A disc-shaped main body 23m sandwiched between the piston stopper 26 and the piston retainer 26 and the second chamber 2 from its outer periphery
The cylindrical peripheral part 23b has an elastic cylindrical peripheral part 23b which becomes larger in diameter toward the cylinder part 2 and is inscribed in the cylinder part 11, and the cylindrical peripheral part 23b is inscribed in the cylinder part 1 to such an extent that it can be rotated by hand. The piston retainer 26 is made of hard synthetic resin, and a metal sleeve 27 is embedded and fixed by insert molding on the inner peripheral surface of the tip portion that is fitted into the piston rod 4, and this sleeve 27 is press-fitted into the piston rod 4. The piston stopper 25 and the piston 23 are
is pressed and fixed to the retaining ring 24.

The piston retainer 26 consists of a flange portion 28 overlaid on the main body portion 23a of the piston 23, a cylindrical portion 29 extending rearward of the piston rod 4, and a bottom portion 30 at the rear end, and has a fluid inlet/outlet 31 in the bottom portion 30. The piston rod 4 has a communication passage 32 that is open to the rear end surface and the outer circumferential surface facing the first chamber 21, and the communication passage 32 branches into a small diameter portion 4a rearward of the press-fitting point of the sleeve 27. It has a throttle passage 33 consisting of an orifice that opens to the outer peripheral surface and communicates with a valve chamber 34 surrounded by the piston rod 4 and the piston retainer 26. Further, the valve chamber 34 has a communication passage 32.
A valve body 35 consisting of a ball that opens and closes is inserted,
Fluid inlet/outlet 31, valve seat 36 at the end of communication path 32, valve chamber 3
4. The valve body 35 constitutes the check valve 3F. It is clear from the drawings that the reverse valve 37 is provided on the same axis at the rear end of the piston rod 4. Furthermore, the flange portion 2
A return spring 38 made of a compression coil spring is press-fitted between 8 and the plug 20.

Incidentally, a screw 39 for attachment is provided on the outer peripheral surface of the cylinder tube 1.

In this embodiment configured in this manner, the piston stopper 25 hits the partition wall 2 due to the spring load of the return spring 38 in the non-operating state as shown in FIG. 1, thereby minimizing the volume of the first chamber 21. The piston 23 moves to the position, and the piston rod 4
The tip of the cylinder protrudes the most from the cylinder tube 1.

When the controlled device comes into contact with the cap 11 and moves the piston rod 4 backward, the first chamber 21 expands and the second chamber 22 contracts, increasing its internal pressure, so the valve body 35 closes the communication path 32. The fluid in the second chamber 22 flows from the valve chamber 34 to the throttle passage 33.
is introduced little by little into the first chamber 21 via the communication path 32,
゛Reduce the operating speed of the controlled equipment. When the controlled device leaves, the piston 23 and piston rod 4 move forward due to the spring load of the return spring 3B, and the valve body 35 opens the communication passage 32 to reduce the first chamber 21 and increase its internal pressure. The fluid is moved from the valve chamber 34 to the second chamber 22 without resistance, and the piston rod 4 is returned to the inoperative position.

The present invention is characterized in that a check valve 37 is installed concentrically with the piston rod 4 on the second chamber 22 side of the piston 23.

The piston retainer 26 is made as a separate part from the piston rod 4 and the piston 23, and is fitted onto the piston rod 4 to form the valve chamber 34 that is constantly in communication with the second chamber 22. This simplifies the cutting process etc. of the piston rod 4. It is possible to reduce the size of the device and the overall size. In this case, the piston retainer 26 may be made of metal, but the present embodiment, in which the part made of synthetic resin and press-fitted into the piston rod 4 is made of metal sleeve 27, has the advantage of being lightweight and being able to be provided at low cost. , and the sleeve 27 is firmly and stably fixed to the piston rod 4 in the correct size.

Further, the throttle passage 33 can be formed very easily by providing it in the small diameter part 4a perpendicular to the axis of the piston rod 4, and communicates with the valve chamber 34 through the gap 39 between the small diameter part 4a and the piston retainer 26. However, as shown in FIG. 3, the entire circumference of the rear end of the piston rod 4 is brought into close contact with the inner circumferential surface of the piston retainer 26 without forming a small diameter portion, and the outer circumferential surface of the piston rod 4 is attached in the axial direction. The groove passage 40 may be formed by hand, and the throttle passage 33 may be communicated with the valve chamber 34 by opening into the groove passage 40.

According to the configuration of this embodiment, firstly, the tip of the piston rod 4 is made into a small diameter part and the cap 11 made of synthetic resin is attached, so for example, the cap 11 can be attached after inserting the backing 14 and other items into the front space. By inserting the unattached piston rod 4 from the rear space, assembly is facilitated, and there is no inconvenience such as the backing 14 being hooked on the piston rod 4 and being damaged, and the cap 11 is in contact with the controlled equipment. This has the advantage of reducing wear.

Second, when the fluid sealed in the first chamber 21 and the second chamber 22 expands due to a rise in temperature and the overall pressure increases, or the pressure in the first chamber 21 increases due to the spring load of the return spring 38. When raised, the backing 14 moves until it comes into contact with the spring receiver 15, and further compresses the push spring 18 and moves to absorb the pressure increase, without impairing the pressure resistance and airtightness of the backing 14.

Thirdly, by fitting the piston stopper 25, piston 23, and piston retainer 26 to the piston rod 4 as separate parts, the diameter and weight of the piston rod 4 can be reduced, and since the piston stopper 25 is in contact with the partition wall 2, the piston The actuation starting point of the rod 4 can be kept constant, and since the piston 23 is inscribed in the cylinder tube 1 so that it can be rotated by hand, it is necessary to assemble the piston after it is assembled. It has the advantage that it can be confirmed by turning the rod 4.

(Effects of the Invention) Since the dashpot of the present invention has a cylinder-piston type, it has a small diameter and is less subject to restrictions on installation location. Further, since the movement of the piston, which is a buffer member, is prevented by the partition wall, it is kept at a constant position when not in operation, and the start point of operation does not change.

Furthermore, even if the fluid is liquid, the amount of sealed liquid is small, so there is almost no bubble generation at high temperatures, and there is little concern that the characteristics will fluctuate.Furthermore, the piston rod is supported by a partition wall and operates stably. As a result, the stability of the operating characteristics is improved, and the controlled device can be properly controlled.

In particular, according to the present invention, the check valve for controlling the movement of fluid between the first chamber and the second chamber is formed concentrically with the piston rod by a piston retainer fitted to the rear end of the piston rod. This further enhances the feature that it can be sufficiently miniaturized and there are few restrictions on the installation location.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention, and FIG.
FIG. 3 is an enlarged partial view of the figure, and FIG. 3 is a vertical cross-sectional partial view showing a different embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Cylinder tube, 2... Partition wall, 4... Piston rod, 21... First chamber, 22... Second chamber, 23...
・Piston, 26...Piston retainer, 27...
Sleeve, 31...Fluid inlet/outlet, 32...Communication path,
33... Throttle passage, 34... Valve chamber, 35... Valve body,
37... Check valve, 38... Return spring,

Claims (1)

[Scope of Claims] 1. A cylinder tube having a partition wall that divides the interior into two front and rear spaces, and a piston rod that traverses the front space, penetrates the partition wall, and is inserted into the rear space. a piston attached to the piston rod and dividing the rear space into a first chamber on the partition wall side and a second chamber on the opposite side; a return spring that pushes the piston toward the partition wall; a piston retainer fitted to the piston rod so as to overlap the second chamber side of the piston; a valve chamber surrounded by the piston rod and the piston retainer and communicating with the second chamber through a fluid inlet/outlet; a communication passage and a throttle passage provided in the valve chamber and communicating the first chamber and the valve chamber; and a valve body inserted into the valve chamber and closing the communication passage when the piston moves toward the second chamber. A dashpot characterized by the following. 2. The dashpot according to claim 1, wherein the piston retainer is made of synthetic resin, and a metal sleeve is fixed to the inner peripheral surface of the tip portion, and this sleeve is press-fitted into the piston rod. 3. The dashpot according to claim 1, wherein the throttle passage branches from the communication passage and opens to the outer circumferential surface of the piston rod, thereby communicating with the valve chamber.