JPS6383475A - Flow control valve - Google Patents

Abstract

PURPOSE:To obtain a low-cost flow control valve by using the proportional property of the quantity of flow passing an oil path formed on a valve element and the displacement of the valve element. CONSTITUTION:The second valve chest 16 and the third valve chest 17 are connected to each other by an oil path formed on the fifth stem portion 11, and the diameter of the fifth stem portion 11 is made larger than that of the forth stem portion 10. In this arrangement, if the operating pressure is not applied, the pressure given to the fifth stem portion 11 is made higher so that a valve element 1 is pressed to the sheet portion side. When the pressure in the third valve chest 17 becomes lower than the balancing pressure, the valve element is moved in the direction of separating from the sheet portion. Pressure oil from the third valve chest 17 is controlled by pressure oil lead-out means. The valve element 1 can be controlled by only one pressure oil lead-out means in such constitution, so that the cost can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flow control valve, and more specifically, to a low-cost flow control valve that can control the flow rate with a single pressure oil remembering means such as a solenoid valve. Regarding control valves.

[Conventional technology]

In contrast to the conventionally used flow rate control valve operated by a manual operation mechanism, a proportional solenoid valve is installed to operate the throttle part, and the valve can be remotely operated in response to an electric signal.
It has been proposed that the flow rate of the hydraulic system can be controlled in an analog manner using command signals from a computer, etc. However, since this conventional technology is equipped with a proportional solenoid valve as described above, the following points are required. There are defects to list.

■ Proportional solenoid valves sacrifice magnetic properties to obtain an attractive force that corresponds to the input current regardless of the position of the mover, so power consumption tends to be high.

■ Due to problems with the magnetic circuit, proportional solenoid valves have a large movable mass, making it impossible to improve frequency response characteristics and the responsiveness of the system as a whole.

■ The sliding resistance (frictional force) of the mover increases in proportion to the eccentricity of the mover in the direction perpendicular to the direction of movement, which causes hysteresis in the attractive force in the direction of movement of the mover, and in the end, the proportional solenoid valve alone is insufficient. Therefore, it is necessary to use a means to ensure control accuracy other than the proportional solenoid valve, such as applying a dither, which is a fine movement signal to cancel the frictional force, or installing a position feedback sensor. It's a hassle.

(2) Since the proportional solenoid valve is controlled in an analog manner, it requires a D/A converter when interfacing with a microcomputer, which is complicated.

(2) There is a risk that foreign matter may be mixed in from an actuator, etc. included in a hydraulic system equipped with the flow control valve, and it cannot be said that the reliability is sufficient.

In order to deal with these problems, the present applicant has developed a flow control valve that can control the flow rate by electric signals without providing a proportional solenoid valve, in Japanese Patent Application Nos. 60-219179 and 60-220367. proposed as.

FIG. 6 shows the configuration of a flow control valve according to the former conventional example, and its outline will be explained.

The flow control valve according to this conventional example has a stem portion of 40°41.
A valve body 51 in which 42, 43, 44 are formed in multiple stages, oil passages 52, 53, valve chambers 54, 55, 56 corresponding to each stem portion 41, 42, 43, 44, and these valve chambers 54, 55.
．． 56 is formed, and is mainly composed of first and second casings 57, 58 that house the valve body 51, and a differential transformer 59 that detects the position of the valve body 51. With two high-speed solenoid valves 60 and 61, the valve body 5
1 is moved to control the flow rate.

The position of the valve body 51, that is, the flow rate, is determined by comparing the input signal with the output signal from the differential transformer 59, and when a difference occurs between the input signal and the output signal, the high-speed solenoid valve 60 Alternatively, by operating 61 so as to eliminate the above-mentioned difference, the setting can be performed with high accuracy.

Further, in the flow control valve according to the latter invention, the differential transformer 59 for detecting the position of the valve body 51 is replaced with a position detection device using a permanent magnet and a magnetic resistance element attached to the valve body 51. In this case as well, two high-speed solenoid valves are required to operate the valve body.

[Problem that the invention seeks to solve]

That is, in the flow control valve proposed by the present applicant,
In order to control the flow rate, two high-speed electromagnetic valves and a valve body position detection device such as a differential transformer or a magnetic resistance element are required, so there is room for improvement in terms of cost.

This invention was made in view of the above technical background,
The purpose is to provide a flow control valve that is low in cost and has the same functions as the conventional example. in particular,
It is an object of the present invention to provide a flow rate control valve that does not require a valve body position detection device and can be controlled with a single electromagnetic valve.

[Means for solving problems]

In order to achieve the above object, the flow control valve of the present invention includes a first stem portion having a seat surface formed on the end surface side, and a first stem portion located at the opposite end of the first stem portion. a second stem portion having the same diameter as the first stem portion, a third stem portion located on the first stem portion side and having the same diameter as the first stem portion, and the second stem portion of the third stem portion. a fourth stem portion located between the fourth stem portion and the second stem portion and having a larger diameter than the third stem portion; The fifth stem part has an oil passage formed therein which leads oil from the fourth stem part side, and an oil passage which communicates the end face of the first stem part with the end face of the second stem part. a first valve that is formed by a third stem portion, a fourth stem portion, and an inner wall of the storage portion; a second chamber formed by a fourth stem portion, a fifth stem portion and the inner wall;
a third valve formed by a second valve chamber, a second stem section, a fifth stem section, and the inner wall, and communicated with the second valve chamber through an oil passage formed in the fifth stem section; a fourth valve chamber formed by the end face of the second stem portion and the inner wall; and first, second and third valve chambers communicating with the first, second and third valve chambers, respectively. A casing including a control oil passage, an oil passage through which pressure oil to be controlled passes and a seat portion that can be brought into contact with the seat surface of the valve body, and from the third control oil passage. and pressure oil deriving means for deriving pressure oil.

[Effect]

The effects of the above means are as follows.

That is, the first stem portion and the second stem portion have the same diameter, and the end surface of the first stem portion and the end surface of the second stem portion are in communication with each other through an oil passage penetrating the valve body. So,
The same pressure is applied to both end faces, and no thrust force is generated between both end faces. Further, if the oil passage leading to the seat portion and through which the pressure oil to be controlled passes is formed between the first stem portion and the third stem portion, the first stem portion and the third stem portion have the same diameter. Therefore, no thrust force is generated from the oil passage between both stem parts. Therefore, no matter how the oil pressure of the oil passage through which the pressure oil to be controlled passes changes, the equilibrium position of the valve body does not change.

On the other hand, the second valve chamber and the third valve chamber are communicated with each other by an oil passage formed in the fifth stem portion, and the fifth stem portion has a larger diameter than the fourth stem portion, so it is particularly difficult to operate the valve chamber. When no pressure is applied, the pressure applied to the fifth stem portion increases, and the valve body is pressed against the seat portion side.

In this state, when pressure oil flows from the third valve chamber to the tank side,
The pressure in the third valve chamber decreases. When the pressure becomes smaller than a predetermined equilibrium pressure, the total pressure applied to the pressure receiving area of the fifth stem part becomes smaller than the total pressure applied to the pressure receiving area of the third and fourth stem parts, and the valve body moves in the direction away from the seat part, that is, towards the valve opening side, and in the opposite case,
Move to the valve opening side. The pressure oil is controlled from this third valve chamber.
This is carried out by pressure oil deriving means such as a solenoid valve, for example, via the third control oil passage.

Therefore, the position of the valve body can be controlled by operating the pressure oil deriving means, and thereby the opening area between the seat surface of the first stem part and the seat part of the body can be adjusted, and the seat part is formed. The flow rate of the pressure oil passing through the oil passage can be controlled via only one pressure oil deriving means.

〔Example〕

Hereinafter, an example of implementation of the present invention will be described based on the drawings.

1 and 5 are for explaining the present invention in detail. FIG. 1 is a partial cross-sectional explanatory diagram of a flow control valve according to an embodiment, and FIG. FIG. 3 is a sectional view of FIG. 2, FIG. 4 is a sectional view of an example of a solenoid valve used to control the flow rate control valve, and FIG. FIG. 2 is an explanatory diagram showing a method of controlling a solenoid valve.

In FIG. 1, the flow control valve according to the embodiment consists of a valve body 1 and first and second casings 2 and 3 that accommodate the valve body 1 movably in the axial direction. is stored in the second casing 2 and connected to the second casing 3 via the O-ring 4.
After the first casing 2 is fitted into the first casing 2, both casings 2 and 3 are fixed by a port 5.

The valve body 1 includes a first stem portion 6 located at the lower end in the figure and further having a conical seat surface 6a formed on the lower surface thereof, a second stem portion 7 located at the upper end, and the above-mentioned first stem portion 6. a third stem part 9 located apart from the first stem part 6 and the small diameter stem part 8; and a fourth stem part 10 located adjacent to the third stem part 9 on the second stem part 7 side. and a fifth stem portion 11 located between the fourth stem portion 10 and the second stem portion 7.

Among these, the first, second and third stem portions 6.7.9
The diameters d, d, d:l are each formed to have the same diameter,
The diameter d4 of the fourth stem portion 10 is larger than the diameters of the first to third stem portions 6, 7.9, and the diameter d of the fifth stem portion 11.

is formed to have a larger diameter than the diameter d4 of the fourth stem portion 10. That is, the diameter of the stem portion is d, = dz
=d, <d4<d.

It is set so that The valve body 1 also has an end face 6 of the first stem portion 6 that passes through the valve body along the axis.
b and the end surface 7a of the second stem portion 7.
2 is formed.

On the other hand, the first casing 2 that houses the valve body 1 has a housing part 2a in a direction that coincides with the axis of the valve body 1, and an oil passage 13 on the lower side of the housing part 2a in the extending direction in the drawing. Oil passages 14 are provided in a direction perpendicular to the oil passage 13, and both oil passages 13 and 14 communicate with each other in an oil chamber 15. The conduits are connected. Further, in the oil chamber 15, a first stem portion 6 and a small-diameter stem portion 8 of the valve body 1 are located, and a valve seat portion facing the sealing surface 6a on the oil passage 13 side of the core oil chamber 15 is located. A seal portion 13a is formed with the same curvature as that of the seal surface 6a.

Further, a first valve chamber 15 is provided in an adjacent portion between the inner wall of the storage portion 2a and the third stem portion 9 and the fourth stem portion 10.
A second valve chamber 16 is located at a portion adjacent to the inner wall and the fourth stem portion 10 and the fifth stem portion 11, and a second valve chamber 16 is located at a portion adjacent to the inner wall and the fifth stem portion 11 and the second stem portion 7. A third valve chamber 17 is formed therein, and a fourth valve chamber 18 is formed between the end surface 7a of the second stem portion 7 and the storage portion 3a of the second casing 3. A control oil passage 19 connected to a hydraulic tank 22 communicates with the first valve chamber 15.
The second valve chamber 16 communicates with an oil passage 20 for control, which is also connected to a hydraulic power source 23 different from the hydraulic power source connected to the oil passages 13 and 14, and the third valve chamber 17 has two A control oil passage 21 connected to a bidirectional high-speed solenoid valve 24 is in communication.

Further, on the outer peripheral surface of the fifth stem portion 11 of the valve body 1,
An oil passage 25 having a substantially triangular planar shape as shown in FIGS. 2 and 3 is cut out. This oil passage 25 is
The apex side 25a of the triangle is connected to the third valve chamber 17, and the bottom side 25a is connected to the third valve chamber 17.
b respectively open into the second valve chamber 16, and even when the valve body 1 is seated, the opening area of the apex side 25a to the third valve chamber 17 can be ensured.

The high-speed solenoid valve 24 connected to the oil passage 21 is 0N=O
It is an FF type, for example, as shown in FIG.
6, a seat surface 30 is formed on this spool 29, and an oil passage 3 is formed.
1 can be opened and closed. One end of the kernel oil passage 31 is connected to the oil passage 2, as shown in FIG. 1, and the other end is connected to the hydraulic tank 22.

In addition, in this flow rate control valve, the oil passage 19 is connected to the pipe line 32 connected from the high-speed solenoid valve 24 to the hydraulic tank 22.
A sequence valve 34 is provided between the core pipe 32 and a pipe 33 connected from the hydraulic power source 23 to the oil passage 20.

Next, the operating principle of the flow control valve configured as described above will be explained.

First, the outer diameter d1 of the first stem portion 6 of the valve body 1 and the outer diameter d2 of the second stem portion 7 are the same diameter, and the oil passage 12
Since the end surfaces 6b and 7a are in communication with each other through the
No thrust force is generated between a. Furthermore, since the outer diameter d of the first stem portion 6 and the outer diameter d3 of the third stem portion 9 adjacent to each other across the small diameter stem portion 8 are the same diameter, the pressure inside the oil passage 13.14 is The pressure applied from the oil to both stem portions 8 and 9 is also equal, and no thrust force is applied to the valve body l from this pressure. Therefore, no external force is applied to the valve body 1 from the pressure oil to be controlled, and the oil passage 13.1
The equilibrium position of the valve body 1 does not change at all even with changes in the oil pressure.

Therefore, when an external force is applied to the valve body 1 from a source other than the pressure oil in the oil passage 13, 14, the valve body 1 can take a position corresponding to the external force.

Therefore, in the above flow control valve, the pressure in the first valve chamber 15 and the oil passage 19 communicating therewith is PT, the pressure in the second valve chamber 16 and the oil passage 20 communicating therein is Ps,
Let the pressure of the third valve chamber 17 and the oil passage 21 communicating with it be PC, and the pressure receiving areas of the valve body 1 in the first to third valve chambers 15, 16, and 17 be A, , A, , AC, respectively. shall be. Under this condition, these pressure receiving areas A, , A, , A
Between C, AC=A, +A, --------
There is the relationship (1).

On the other hand, when the high-speed solenoid valve 24 is blocked as shown in FIG. 1, the third valve chamber 17 communicates with the second valve chamber 16 via the oil passage 25, and the Since there is no flow, the pressure relationship is PC=P.

Therefore, in addition to the hydraulic pressure applied to the valve body 1, the force that presses the valve body 1 toward the seat portion 13a is f, the seat portion 13a
Letting f2 be the force acting in the direction of separating from the , then f, = Ac = PC = Ae - P.

= (A, +A, r) ps ・
... (2) rz = As ・Ps + Ar
・Pt”...Since the relationship is as shown in (3), the magnitude relationship between force f and f2 is f+ fz = (
A, -Ps +Ar -Ps)=(A,・ps
+Ar −PT )=A−(Ps Pt) ・
...(4). Here, between the pressures P and Pa, P is the pump inlet pressure and Pr is the tank pressure, so Ps > Pa, and the force relationship is r,>f from equation (4).

becomes. Therefore, when the high-speed solenoid valve 24 is in the blocking position, the valve body 1 is pressed against the seat portion 13a, and the oil passages 13, 14 are closed.

Next, when the high-speed solenoid valve 24 is energized and the oil passage 21 and the hydraulic tank 22 are connected, the pressure Pe in the third valve chamber 17 and the oil passage 21 is different from the pressure P8 in the second valve chamber 16. are no longer equal (Pcf-Ps).

Therefore, if the pressure in the third valve chamber 17 at this time is PC, then the relationship in equation (4) is f 1 fz=Ae
HPc (As ・Pg +Ar ・Pt)
Then, finding a PC that satisfies f,-1, we get ACA
It becomes C. Therefore, the pressure that satisfies this f, = f2 is PC
1, the pressure PC in the third valve chamber 17 is p c 〉
If p cr, the valve body l moves to the seat portion 13a side, that is, to the valve closing side, and if PC<Pcr, the valve body l moves to the seat portion 13a side, that is, the valve closing side.
It moves in the direction away from 3a, that is, toward the valve opening side. Therefore, by controlling the pressure in the third valve chamber 17, it becomes possible to control the opening degree of the valve body 1 and the flow rate of the pressure oil flowing through the oil passages 13 and 14. The pressure within the third valve chamber 17 is controlled from the second valve chamber 16 to the third valve chamber 1 via an oil passage 25 formed in the fifth stem portion 11.
7, and the flow rate Q0.M flowing into the third valve chamber 17 via the high-speed solenoid valve 25. ．． This is done by controlling the magnitude relationship between

This will be explained in more detail.

In Fig. 2, when the valve body 1 is displaced by X, the oil passage 2
The apex side 25a of the notch 5 opens into the third valve chamber 17 by a width 2 as shown. Here, if the groove depth of the core oil passage 25 is h as shown in FIG. 3, and if n such oil passages 25 are formed in the fifth stem portion 11, then The opening area of the oil passage 25 communicating with the third valve chamber 17 to the third valve chamber 17 is nzh.

At this time, since there is a proportional relationship between the valve displacement
becomes aX=nz h=nαxh = (6).

Also, when the high-speed solenoid valve 24 is ON, the displacement of the valve body 1 is
, if the pressure in the third valve chamber 17 is Pc, then the inflow flow rate Q in to the valve chamber 17 is XF.
...(7) becomes. Here, g is the acceleration of gravity, and γ is the specific gravity of the working fluid.

On the other hand, the opening area of the high-speed solenoid valve 24 when it is turned on is a. , if the flow coefficient is 08, then the flow -1iJQ flows out from the third valve chamber 17 via the high-speed solenoid valve 24. . ,teeth,····
...(8), and the pressure Pc of the third valve chamber 17 is the valve chamber volume.
If the bulk modulus of the working fluid is , then -dP to c/
It is determined from the relationship c/dt t. Then, when the valve body 1 is statically fixed, dPc/dt=0 and dx/dt=0, so
Assuming this state, Q i 1% = Q Ou
It is L. Using equations (7) and (8) to find the displacement , the pressure PC in equation (10) must be the pcr value described above. Using this relationship, we get . Furthermore, AC-A is obtained from equation (1).

Using the relationship =A, AC-A, =A, we can derive. This equation (11) shows that there is a proportional relationship between the displacement X of the valve body 1 and the opening area a of the high-speed solenoid valve 24.

By the way, the high-speed solenoid valve 24 uses a seat valve type ON-OFF valve as described above, and when the valve body 1 is seated, the third
This is intended to prevent malfunctions caused by leakage from the valve chamber 17, but if it is an 0N-OFF valve, the opening area a8 of the high-speed solenoid valve 24 in equation (11) will be either a8=0 or a
, =a, and therefore, when the high-speed solenoid valve 24 is operated in a normal manner, the valve body 1 cannot be controlled continuously. Therefore, the method of driving the high-speed solenoid valve 24 becomes a problem. In contrast, this embodiment employs a special driving method as described below.

That is, considering the energization time τ to the high-speed solenoid valve 24 within a certain period T, if the period T is set sufficiently short,
The opening area a of the high-speed solenoid valve 24 is, on average, τ/T-
Since the value of a is taken, equation (II) becomes: (12) where the energization time τ of the high-speed solenoid valve 24 and the displacement
It can be seen that they are proportional.

This example is specifically shown in FIGS. 5(a), (b), and (c). Figure 5 (a) shows that τ/T is 25% and Figure 5 (
b), τ/T is 50%, and Figure 5(C), τ/T is 7.
In the case of 5%, by controlling /T with this energization time ratio, it is possible to obtain the displacement X of the valve body 1 having a proportional relationship with τ/T.

In the above embodiment, the valve body 1 is driven by the oil passage 13.
．． The valve body 1 is not affected by pressure fluctuations in the main circuit, and is only operated by the pilot pressure supplied via the high-speed solenoid valve 24. Since the valve is driven, the valve opening is very large.

In addition, by forming the oil passage 25 as described above, utilizing the proportional relationship between the displacement of the valve body 1 and the opening area of the high-speed solenoid valve 24, and employing the above control method, the valve displacement can be controlled. The flow rate can be controlled without any detection means and with just one high-speed solenoid valve 24.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, which is configured to control the flow rate by utilizing the proportionality between the flow rate passing through the oil passage formed in the valve body and the displacement of the valve body, By correlating this with the displacement of the valve body, there is no need for a means for detecting the position of the valve body, and the flow rate can be controlled with just one pressure oil introduction means that creates a differential pressure in the flow path. For example, it is possible to provide an inexpensive flow control valve that can be controlled using only a single solenoid valve.

[Brief explanation of the drawing]

1 to 5 are for explaining the present invention in detail. FIG. 1 is a partial cross-sectional explanatory diagram of a flow control valve according to an embodiment, and FIG. 2 is an enlarged view of the main parts of the flow control valve. Figure 3 is a sectional view taken along line /l-A in Figure 2, Figure 4 is a sectional view showing an example of a solenoid valve used for control, Figure 5(a), (
b) and (c) are explanatory diagrams for explaining the control method, respectively, and FIG. 6 is an explanatory diagram of a flow control valve according to a conventional example. DESCRIPTION OF SYMBOLS 1... Valve body, 2... First casing, 3... Second casing, 6... First stem portion, 6a... ...Seat surface, 6b...
...End face, 7...Second stem portion, 7a...
...End face, 9...Third stem portion, 10.
...Fourth stem part, 11...Fifth stem part, 12.13.14...Oil passage, 15.
...First valve chamber, 16...Second valve chamber,
17...Third valve chamber, 18...Fourth valve chamber, 19.20.21...Oil passage, 24...
... Solenoid valve, 25 ... Oil line. 6σ erB12 Fig. 2 Fig. 3 Fig. 4 Fig. 5 (σ) Cb) (C) Fig. 6

Claims (2)

[Claims] (1) A first stem portion having a seat surface formed on the end surface side; a second stem portion located at the opposite end of the first stem portion and having the same diameter as the first stem portion; a third stem portion located on the first stem portion side and having the same diameter as the first stem portion; and a third stem portion located on the second stem portion side of the third stem portion. a fourth stem portion having a larger diameter;
a fifth stem part located between the stem part and the second stem part, which has a larger diameter than the fourth stem part and is formed with an oil passage for guiding oil from the fourth stem part side; , a valve body having an oil passage communicating the end face of the first stem part and the end face of the second stem part; and the valve body is stored in a storage part so as to be reciprocally movable; a first valve chamber formed by a third stem portion, a fourth stem portion, and an inner wall of the housing portion; a first valve chamber formed by a fourth stem portion, a fifth stem portion, and the inner wall; a second valve chamber formed by a second stem portion, a fifth stem portion, and the inner wall, and communicated with the second valve chamber by an oil passage formed in the fifth stem portion; a third valve chamber formed by the end surface of the second stem portion and the inner wall; a first control oil passage communicating with the first valve chamber;
The pressure oil to be controlled passes through a second control oil passage that connects the second valve chamber and the hydraulic pressure source, and a third control oil passage that communicates with the third valve chamber. It is characterized by comprising: a casing having an oil passage formed with a seat portion that can be brought into contact with the seat surface of the valve body; and pressure oil deriving means for deriving pressure oil from the third control oil passage. flow control valve. (2) Claim (1) is characterized in that the oil passage formed in the fifth stem portion is a cutout groove having a constant depth and having a substantially triangular shape in plan view. Flow control valve.