JP2000214932A - Pressure control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure durability by protruding a protrusion which extends the bottom part sheet surface of a piston to a high-pressure side in the piston slide direction and forming a fine-sectional-area passage between the external surface of the protrusion and the internal surface of a case which extends in the piston slide direction. SOLUTION: The protrusion 21 which extends from the inner peripheral edge of the bottom part sheet surface 6 to the high-pressure side (lower) in the piston slide direction (along the center line 20 of the piston 5) is provided integrally with the piston bottom part 22. The fine-sectional-area passage 25 which is annularly sectioned is formed between the external surface 23 of the protrusion 21 and the cylindrical internal surface 24 of the case 1 which faces it and extends in the piston slide direction. Thus, the fine-sectional-area passage 25 having nearly specific length L is provided and its sectional area is small, so even when the piston 5 begins to be listed, the piston 5 serves for resistance and the hydraulic pressure in a high-pressure side oil passage 2 does not drop abruptly. Consequently, a pulsation rate is held at a low value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control valve disposed in a hydraulic system such as a hydraulic device or a prime mover.

[0002]

2. Description of the Related Art As shown in FIG. 6, a bottom seat surface 6 of a bottomed piston 5 urged toward a high pressure side on a valve seat surface 4 between a high pressure side oil passage 2 and a low pressure side oil passage 3 in a case 1. Is configured to be seated. 7 is a compression spring for urging, 8 is a hole for release, and 9 is a pressure regulating valve. The high-pressure side oil passage 2 will be described with reference to FIG. 1 showing an embodiment of the present invention. The high-pressure side oil passage 2 is connected to a discharge port of a lubricating oil pump 13 via an oil passage 12 and to each lubricating point via a hole 14. are doing. The low-pressure side oil passage 3 is connected to a tank 16 via an oil passage 15.

When the pressure in the high-pressure side oil passage 2 becomes equal to or higher than a set pressure determined by the spring 7, the piston 5 lifts in the direction of arrow A and starts valve opening, so that the pressure in the high-pressure side oil passage 2 immediately decreases. And low pressure repeatedly. That is, the sheet surfaces 4 and 6 are repeatedly opened and closed, and are hit. The broken lines in FIGS. 4 and 5 show the characteristics of the conventional structure shown in FIG. 6. In particular, FIG. 5 shows that the conventional structure has a rotation speed region where the pulsation rate is extremely high, and the pulsation rate is high over a wide rotation speed range. Is shown. As described above, in the conventional structure, the abnormal noise when opening and closing the seat surface (jiggling sound due to the slamming phenomenon of the seat surface caused by the pulsation of the hydraulic pressure in the minute lift region (in a state where the pressure is adjusted). It is very uncomfortable and causes complaints). The prior art is disclosed in Japanese Patent Application Laid-Open No. 07-310672.
There is a number.

[0004]

The object of the present invention is to prevent the occurrence of abnormal noise due to the phenomenon of hitting the sheet surface during pressure adjustment.

[0005]

According to a first aspect of the present invention, a bottom seat surface of a bottomed piston urged toward a high pressure side is provided on a valve seat surface between a high pressure side oil passage and a low pressure side oil passage in a case. In the pressure regulating valve to be seated, a protruding portion extending in the piston sliding direction from the bottom seat surface of the piston toward the high pressure side protrudes, and an outer surface of the protruding portion and an inner surface of the case extending in the piston sliding direction are formed. A pressure regulating valve, characterized in that a minute cross-sectional area passage having a predetermined length is formed therebetween.

According to a second aspect of the present invention, there is provided the pressure regulating valve according to the first aspect, wherein a concave portion for reducing the weight is formed inside the distal end surface on the high pressure side of the projecting portion.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 showing one embodiment of the present invention, the same reference numerals as those in FIG. 6 denote the same or corresponding parts. High pressure side (downward) from the inner peripheral edge of the bottom seat surface 6 in FIG.
Toward the piston (the center line 20 of the piston 5)
The protrusion 21 extends in a direction along the piston bottom 22 and is integrally formed with the piston bottom 22. The outer surface 23 of the protrusion 21 shown in the drawing has a cylindrical shape, and the protrusion length L varies depending on the application, but is, for example, 1 to 10 mm. , Preferably 2-7 mm, the function of which will be described later in connection with FIGS. Between the outer surface 23 of the protruding portion 21 and the cylindrical inner surface 24 extending in the direction of sliding of the piston of the case 1 opposed thereto, there is formed a small cross-sectional area passage 25 having an annular cross section (a throttle portion..., See FIG. 2). I have. The width of the passage 25 in the radial direction varies depending on the application.
5 to 5 mm, preferably 1 to 2 mm, the function of which will be described later with reference to FIGS. A concave portion 27 for weight reduction (for mass removal) is provided inside the high-pressure end surface 26 of the protruding portion 21. In FIG. 1, reference numeral 10 denotes an escape hole, and reference numeral 11 denotes a cap.

When the hydraulic pressure in the high-pressure side oil passage 2 in FIG. 1 rises above a set value and the piston 5 rises in the direction of arrow A, the bottom seat surface 6 separates upward from the valve seat surface 4,
With the lift amount L3 in FIG. 4, the cross-sectional area between the two seat surfaces 6, 4 becomes equal to the cross-sectional area of the minute cross-sectional area passage 25, and from there, L4
Up to this point, the passage area does not change due to the length L of the protruding portion 21 (pre-lift portion = 1), and as the lower edge of the outer surface 23 further rises, the passage area increases substantially in parallel with the conventional broken line. That is, when the point P in FIG. 4 is set to the valve opening position, the valve is opened with the lift amount L4 in the conventional structure, but is opened with the lift amount L4 + 1 (that is, the lift amount L1) in the pressure regulating valve 9a of the present invention. .

As described above, according to the present invention, since the passage 25 having a small sectional area having a substantially predetermined length L is provided and the sectional area thereof is small, the passage 25 becomes a resistance even when the piston 5 starts lifting, and the high pressure The oil pressure in the side oil passage 2 does not drop suddenly. The pulsation rate is maintained at a low value as shown by the solid line in FIG.

[0010]

According to the first aspect of the present invention, even if the supply oil pressure fluctuates, the seat surfaces 4, 6 are not damaged by the vibration of the piston 5, and the durability can be ensured. In addition, it is possible to prevent the tapping sound (jizzy sound) of the seat without impairing the reliability and the hydraulic characteristics of the pressure adjusting valve 9a. Further, the fluctuation of the circuit oil pressure is reduced. Further, the conventional problems can be solved only by changing the shape of the piston 5 without changing the parts on the case 1 side in which the piston 5 is accommodated. Claim 2
According to the invention, the weight (mass) of the piston 5 is reduced by the concave portion 27, so that not only the weight of the pressure regulating valve 9a is reduced, but also the pressure regulating function becomes sharp.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional front view of a pressure regulating valve according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a side view of the piston of FIG. 2;

FIG. 4 is a graph showing a relationship between a minimum passage area and a lift amount.

FIG. 5 is a graph showing a relationship between a pulsation rate and an engine speed.

FIG. 6 is a drawing corresponding to FIG. 2 showing a conventional structure.

FIG. 7 is a side view of the piston of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 High-pressure side oil passage 3 Low-pressure side oil passage 4 Valve seat surface 5 Bottomed piston 6 Bottom seat surface 7 Spring 9a Pressure regulating valve 20 Center line (piston sliding direction) 21 Projection 23 Outer surface 24 Inner surface 25 Area passage 27 recess

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Eikichi Saito 1-32 Chaya-cho, Kita-ku, Osaka-shi, Osaka F-term in Yanmar Diesel Co., Ltd. 3H059 AA04 BB03 BB22 BB37 BB38 CA04 CA05 CC02 CD05 CF14 EE01 FF03 FF13 3H066 AA01 BA17 BA32 BA34 BA38 5H316 AA18 BB09 DD11 DD20 EE04 EE10 EE12 EE30 GG01 JJ01 JJ13 KK01

Claims (2)

[Claims] 1. A pressure regulating valve in which a bottom seat surface of a bottomed piston urged toward a high pressure side is seated on a valve seat surface between a high pressure side oil passage and a low pressure side oil passage in a case,
A protruding portion extending in the piston sliding direction from the bottom seat surface of the piston toward the high pressure side is protruded, and a small cross-sectional area passage having a predetermined length is provided between an outer surface of the protruding portion and an inner surface of the case extending in the piston sliding direction. A pressure regulating valve characterized by forming: 2. The pressure regulating valve according to claim 1, wherein a concave portion for reducing the weight is formed inside the front end surface on the high pressure side of the projecting portion.