JPH0520937Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a relief valve used for pressure regulation in a hydraulic circuit or the like.

[Conventional technology]

An example of a relief valve in which the circuit hydraulic pressure at the time of starting the relief valve is gradually increased over time is shown in the 10th example.
The diagram will be explained. In the figure, a poppet 52 and a spring seat 53 are fitted into a valve body 51 so as to be movable back and forth, and a spring 54 interposed therebetween allows the poppet 5 to be moved back and forth.
2 to the seat 55, the spring seat 53 to the plug 57 forming the rear wall of the liquid chamber 56, and one end inserted into the poppet 52 and the other end inserted through the spring seat 53 to open the supply passage 58. The rod 59 that contacts the plug 57 with pressure oil has a long hole 60 that is blind on the plug 57 side and a horizontal hole 61 that communicates with the deep part of the hole 60, and the spring seat 53 has an annular groove that communicates with the horizontal hole 61. 63 and a passage 64 that communicates between the annular groove 63 and the liquid chamber 56 is formed. (For example, see Utility Model Publication No. 57-100675.) In such a relief valve, when the hydraulic pressure of the supply passage 58 overcomes the elastic force of the spring 54 of the relief valve, the poppet 52 resists the spring 54 and the seat 55
The body moves away from the body and begins to act as a relief. Also, on the one hand, the eccentric hole 65 of the poppet 52, the axially elongated hole 60 of the rod 59, the horizontal hole 61, the annular groove 63, and the passage 64.
Pressure oil in the supply passage 58 introduced into the liquid chamber 56 through the spring seat 53 responds to the pressure increase in the supply passage 58.
is moved against the spring 54. As a result, the spring 54 is gradually compressed and the relief pressure increases, but at this time, the horizontal hole 61 of the rod 59 is narrowed by the annular groove 63 due to the movement of the spring seat 53, so the amount of pressure oil flowing into the liquid chamber 56 gradually decreases. The relief pressure increases relatively slowly.

[Problem that the invention attempts to solve]

By the way, this relief valve has an annular groove 6 in the spring seat 53 in order to gradually reduce the amount of pressure oil flowing into the liquid chamber 56.
3 to narrow the horizontal hole 61 of the rod 59, the elongated hole 60 of the rod 59 is a small hole with no end, and the horizontal hole 61 is required on the circumference, making hole machining troublesome. In addition, in order to obtain a predetermined pressure increase characteristic, the valve body 51, plug 57, annular groove 63, and through hole 64 are designed so that the opening area that regulates the amount of pressure oil flowing into the liquid chamber 56 changes accordingly. Dimensional accuracy in the axial direction must be achieved for four parts: the spring seat 53, and the rod 59, which has the horizontal hole 61 and the elongated hole 60. For this reason, processing is difficult.

The present invention has been made in view of the above points, and aims to provide a relief valve which is easy to process rods, etc. and form a throttle passage, etc., and in which the pressure rise is approximately linear and gradual when the relief valve is operated. .

[Means for solving problems]

The first configuration of the present invention to achieve this purpose is
This will be explained using figures.

A means for guiding pressure fluid on the supply side from the throttle hole of the plunger to a liquid chamber behind the spring receiver, a spring receiver that compresses the spring by supplying this pressure fluid and adjusts the set pressure, and a spring receiver for adjusting the set pressure. In the relief valve, the relief valve is equipped with a means for slowing down the movement speed in the spring compression direction,
The spring receiving portion is formed into a stepped spring receiving piston portion 7 that is fitted into the stepped cylinder portion 6 of the valve body 5, and the stepped spring receiving piston portion 7 and the stepped cylinder portion 6 form a damping chamber at the stepped portion. 8, the damping chamber 8 is communicated with the liquid chamber 2 or the spring chamber 9 via a throttle passage 10 or 10' formed by a stepped cylinder section 6 and a stepped spring receiving piston section 7, and a plunger The throttle hole 19 of No. 3 and the liquid chamber 2 are communicated through a through hole 20 of a rod 11 whose one end is fitted into the plunger 3 and the other end is inserted through the stepped spring receiving piston portion 7. It is something.

[Effect]

When the hydraulic pressure in the supply passage 1 overcomes the elastic force of the spring 4, the plunger 3 lifts and the relief valve starts its relief action. On the other hand, the pressure fluid in the supply passage 1 flows into the fluid chamber 2, and this pressure fluid moves the stepped spring receiver piston part 7 against the spring 4 in response to the rise in supply side fluid pressure.
move against. As a result, the spring 4 is compressed and the relief pressure increases, but as will be explained later in the operating principle of the relief valve of the present invention, the relief pressure increases approximately linearly and gradually until it reaches the final set pressure.

By the way, in the present invention, the rod 11 that guides the supply side pressure liquid to the liquid chamber 2 only needs to have a through hole, so a pipe can be used. The throttle passages 10 and 10' connected to the damping chamber 8 are connected to the sliding surfaces 21, 22, 27 of the stepped cylinder section 6 and the stepped spring receiving piston section 7, respectively.
28, the dimensional accuracy of the position of the throttle passages 10, 10' can be achieved by three parts: the valve body 5, the stepped spring receiving piston part 7, and the plug 12 that locks the rod 11.

Next, the operating principle of the relief valve of the present invention will be explained.

The seat area of plunger 3 and seat 17 is
S ₁ is the cross-sectional area of the rod 11, S ₂ is the cross-sectional area of the large diameter portion of the stepped _{spring bearing piston portion 7, and S 4 is} the cross-sectional area of the small diameter portion.
shall be.

Further, the upstream pressure of the plunger 3 (i.e. relief pressure) is P _A , the pressure in the through hole 20 and the liquid chamber 2 (differential chamber pressure) is P _B , the initial load of the spring 4 is F ₁ ,
Let F ₂ be the load when the stepped spring bearing piston part 7 reaches the stroke end.

First, consider the case where the supply passage 1 is pressurized from tank pressure. Supply passage 1 is initially at tank pressure;
Since the through hole 20 and the liquid chamber 2 are also at tank pressure, the stepped spring receiving piston part 7 is pressed against the plug 1 by the spring 4.
It is in a state where it is pressed against 2.

If no damping force is currently acting on the stepped spring receiver piston portion 7, the through hole 20 and the liquid chamber 2
_Due to the mechanical balance of the stepped spring bearing piston part 7 with respect to the initial load F ₁ of the spring 4, _the pressure P _{B of is} calculated as follows: P _B1 (S ₄ − S ₂ )=F _{1 2} ) The relief pressure P _A1 at this time is P _A1 S ₁ = F ₁ + P _B1 S ₂ P _A1 = (F ₁ + P _B1 S ₂ )/S ₁ This P _A1 is the pressure increase start pressure. If no damping force is acting on the stepped spring receiver piston part 7, pressure oil will flow into the through hole 20 and the liquid chamber 2 through the throttle 19 with a pressure difference of ΔP = P _A - P _B , thereby causing The stepped spring receiver piston portion 7 is moved downward. If the pressure P _B in the liquid chamber 2 just before the stepped spring bearing piston part 7 reaches the stroke end is P _B2 , then P _B2 (S ₄ - S ₂ ) = F ₂ P _B2 = F ₂ / (S ₄ - S ₂ ) The relief pressure at this time is P _A2 = (F ₂ + P _B2 S ₂ )/S ₁ However, at the moment when the stepped spring receiver piston part 7 reaches the stroke end, the through hole 20 and the liquid chamber 2
Since the pressure P _B and the relief pressure P _A are the same,
Relief pressure P _A increases rapidly.

That is, the pressure increases as shown in FIGS. 6 and 7.

In such a state, it cannot be said that the pressure rise is gradual. Therefore, in the present invention, by providing the damping chamber 8 at the stepped portion of the stepped spring receiving piston section 7 and the stepped cylinder section 6, the back pressure of the damping chamber 8 is applied to the stepped spring receiving piston section 7. to act.

That is, the damping chamber 8 is arranged such that as the stepped spring receiving piston section 7 strokes, a large damping force acts on the stepped spring receiving piston section 7.
A throttle passage 10 is formed between the damping chamber 8 and the spring chamber 9, or a throttle passage 10' is formed between the damping chamber 8 and the liquid chamber 2. The back pressure in the damping chamber 8 at this time is defined as P _C.

The equations expressing the time changes in each pressure of P _A , P _B , and P _C are as follows: P _A (t)...Time function of relief pressure P _B (t)...Time function of differential chamber pressure P _C (t )... Time function of the pressure in the damping chamber 8 F (t)... Time function of the _elastic force of the spring ₄ )=S ₂ P _B (t) + F(t) ……(1) Dynamic equilibrium equation acting on the stepped spring receiver piston part 7 (S ₃ −S ₂ )P _B (t)=(S ₃ −S ₄ ) P _C (t) + F(t) ...(2) If the time function of the flow rate flowing from the throttle 19 to the liquid chamber 2 is Q(t), then the damping throttle is In the case Q(t)=(S ₃ −S ₂ )dx/dt...(3) When the damping orifice is of the throttle passage 10′ (Fig. 5) Q(t)=(S ₄ −S ₂ )dx /dt...(3) If the diaphragm 19 is an orifice, then from Bernoulli's equation, P _A (t)−P _B (t)=ρ{Q(t)} ² /2C ² F ² ...(4) However, C is the flow coefficient, and ρ is the hydraulic oil density.Also, the time function F(t) of the elastic force of the spring 4 is, if the spring constant is k, F(t)=F ₁ +kdx...(5) Above ~ Equation From, P _A (t), P _B (t), P _C (t), F(t),
Five variables of Q(t) are found. The following conclusions can be drawn from the obtained results.

The time required for P _A (t) and P _B (t) to rise to the final set pressure is the time from when the stepped spring receiver piston section 7 starts its stroke until it reaches the stroke end. is controlled by the flow rate Q(t) of pressure oil flowing into the liquid chamber 2 through the throttle 19 (
formula).

On the other hand, the flow rate Q(t) is governed by the differential pressure between P _A (t) and P _B (t) (formula).

From the formula, P _A (t)−P _B (t)=(S ₂ P _B (t)+F(t))/S ₁ −P _B (t)=
F(t)/S ₁ −(1−S ₂ /S ₁ )P _B (t) On the other hand, as is clear from the equation, P _B (t) is when damping is acting, that is, P _C ( t) is acting, the required P _B (t) becomes larger than when there is no damping. Also, in the previous equation, 1-S ₂ /S ₁ >
Since it is 0, when damping is acting, that is, when P _C (t) is acting, P _A (t) - P _B (t) becomes small.

Therefore, when damping is acting on the stepped spring receiver piston portion 7, the time function Q(t) of the flow rate flowing into the liquid chamber 2 becomes small.

That is, the time required for the stepped spring receiver piston portion 7 to reach the stroke end after starting the stroke is longer when damping is acting. In addition, by appropriately selecting the throttle passage 10 or 10', P _B (t) and
P _A (t) can be made to continue smoothly until reaching the final set pressure Pset as shown in FIGS. 8 and 9.

In this way, the pressure increase time td until reaching the final set pressure is compared to the pressure increase time t ₀ when there is no damping.
It is possible to satisfy td>t ₀ and to increase the pressure substantially linearly and gradually until the final set pressure is reached.

〔Example〕

Embodiments of the present invention will be described based on the drawings. In FIG. 1, the valve body 5 is composed of a bubble casing 13 and a sleeve 14 attached to the bubble casing 13. The sleeve 14 has a supply passage 1 and a return passage 16, and a seat 1 is formed on the supply passage 1 side.
7 and a plug 12 is fixed to the other end. Inside the sleeve 14 between the seat 17 and the plug 12 is a plunger 3 which is slidably inserted into the sleeve 14.
Spring 4, a stepped spring receiving piston part 7 tightly fitted into the stepped cylinder part 6 of the sleeve 14 so as to be freely movable and retractable, and a rod having one end fitted into the plunger 3 and the other end inserted through the stepped spring receiving piston part 7. 11, the plunger 3 is brought into contact with the seat 17 by the spring 4, and the stepped spring receiving piston part 7 is brought into contact with the plug 12. The plug 12 forms a liquid chamber 2 with the stepped spring receiving piston portion 7, the sleeve 14, and the rod 11.
The plunger 3 has a hole 18 into which the rod 11 is inserted.
and a throttle hole 19 communicating this hole with the supply passage 1, and the rod 11 is provided with a hole 18 of the plunger 3.
A through hole 20 is provided that communicates the liquid chamber 2 with the liquid chamber 2 .

The stepped spring bearing piston portion 7 is the stepped cylinder portion 6
A damping chamber 8 is formed at the stepped portion.
In this damping chamber 8, as shown in FIG. By connecting the annular groove 24 and the spring chamber 9 through the small radial holes 25 formed in the stepped spring bearing piston part 7 and the axial hole 26, the stepped spring bearing piston part 7 moves in the direction of compressing the spring 4, the damping chamber 8 moves between the annular groove 24 and the sliding surface 2, as shown in FIG.
The spring chamber 4 is connected to the spring chamber 4 through the throttle passage 10 formed by the
communicate with. Alternatively, the damping chamber 8 may be connected to the liquid chamber 2 as shown by imaginary lines in FIG. In this case, as shown in FIG.
Annular grooves 29 and 30 with a very shallow depth are formed at the location where the damping chamber 8 connects with the liquid chamber 2, and the annular groove 30 and the damping chamber 8 are connected by a through hole 31 formed in the stepped spring receiving piston part 7. As a result, when the stepped spring receiving piston portion 7 moves in the direction of compressing the spring 4, the damping chamber 8 is formed in the throttle passage 1 formed by the annular groove 30 and the sliding surface 27, as shown in FIG.
It communicates with the liquid chamber 2 via 0'.

In the damping mechanism shown in FIGS. 2 and 4, when the stepped spring receiver piston 7 starts moving against the spring 4 due to the pressure fluid in the liquid chamber 2, the damping mechanism shown in FIGS. Then, the pressure fluid in the damping chamber 8 flows in the direction of the arrow with relatively little resistance, resulting in a slight pressure increase, and then, as shown in FIGS. 3 and 5, the pressure fluid passes through the throttle passages 10 and 10', as described above As described above, the pressure rises approximately linearly and gradually until the final set pressure is reached.

Therefore, for example, if the relief valve of this invention is used in the rotating body brake circuit, the shock at the time of stopping can be alleviated.

[Effect of idea]

As is clear from the above explanation, according to the present invention, when the relief valve starts to start, the pressure fluid in the damping chamber is discharged through the throttle passage into the fluid chamber or spring chamber behind the stepped spring receiver piston section. Therefore, the circuit pressure when the relief valve is started increases approximately linearly and gradually. In addition, as a means for slowing down the moving speed of the stepped spring receiver piston in the spring compression direction, a damping chamber is formed at the stepped portion by the stepped cylinder of the valve body and the stepped spring receiver piston that fits into the stepped cylinder. Since the throttle passage communicates with the liquid chamber or the spring chamber, the dimensional accuracy of the means in the axial direction defines the retraction limit of the stepped cylinder part, the stepped spring bearing piston part, and the stepped spring bearing piston part. It is easier to manufacture than the conventional product (Fig. 10), which has four points: the valve body, the spring seat, the rod, and the stopper that defines the retraction limit of the spring seat. can.
Furthermore, since a pipe can be used as a means for guiding the supply-side pressurized liquid from the plunger to the liquid chamber behind the stepped spring receiver piston portion, no hole drilling or plugging is required, and costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway vertical sectional view of an embodiment of the present invention, Fig. 2 is a partially cutaway sectional view of the damping mechanism of the same embodiment, Fig. 3 is an explanatory diagram of the damping action of the damping mechanism, Fig. 4 is a partially cutaway sectional view of a damping mechanism according to another embodiment of the present invention, Fig. 5 is an explanatory view of the damping action of the same damping mechanism, and Fig. 6 is a stepped spring receiver piston section when there is no damping chamber. A chart showing the fluctuation state of the hydraulic pressure P _B acting on the stepped spring receiver piston at the moment when the piston reaches the stroke end, Figure 7 is a chart showing the fluctuation state of the relief pressure P _A , and Figure 8 is a diagram showing the fluctuation state of the relief pressure P A. 9 is a chart showing the relationship between the hydraulic pressure acting on the stepped spring receiver piston section and time when the relief valve is started, FIG. 9 is a chart showing the relationship between the relief pressure and time, and FIG. It is a partially cutaway longitudinal sectional view of a conventional product. DESCRIPTION OF SYMBOLS 1... Supply passage, 2... Liquid chamber, 3... Plunger, 4... Spring, 5... Valve body, 6... Stepped cylinder part, 7... Stepped spring receiving piston part, 8...
Damping chamber, 9... Spring chamber, 10, 10'...
Aperture passage.

Claims (1)

[Scope of utility model registration request] A means for guiding pressure fluid on the supply side from the throttle hole of the plunger to a liquid chamber behind the spring receiver, a spring receiver that compresses the spring by supplying this pressure fluid and adjusts the set pressure, and a spring receiver for adjusting the set pressure. In the relief valve, the relief valve is equipped with a means for slowing down the movement speed in the spring compression direction,
The spring receiving portion is a stepped spring receiving piston portion that is inserted into the stepped cylinder portion of the valve body, and the stepped spring receiving piston portion and the stepped cylinder portion form a damping chamber at the stepped portion. The damping chamber is communicated with the liquid chamber or the spring chamber through a throttle passage formed by a stepped spring receiving piston section and a stepped cylinder section, and the throttle hole of the plunger and the liquid chamber are connected to each other by connecting one end of the damping chamber to the liquid chamber or the spring chamber. A relief valve characterized in that the other end of the rod is inserted into the stepped spring receiving piston and communicates with the through hole of the rod.