JPH0674279A - Passage area adjusting mechanism - Google Patents

Abstract

PURPOSE:To provide passage area adjusting mechanism allowing the variable width of passage area to be set large and the passage area to be changed into linear form in relation to the stroke of a piezoelectric body while being of simple constitution and enabling required space to be relatively small. CONSTITUTION:A flexible plate 45 is inserted between a second piston 40 and a collar part 44, provided at the lower part of a fixed base 43 in such a state that the center part is previously bent slightly inward and the initial flexure is mutually opposed. A valve inner cylinder 63 is energized by the reaction of a return spring 81, and its movement is regulated in the state of being pressed to the center part 45a of the flexible plate 45. The passage groove 77 of a valve outer cylinder 60 is formed in such a way that the passage area S is changed into linear form in relation to the stroke of a laminated type piezoelectric body 27. The displacement of the laminated type piezoelectric body 27 is enlarged to the extent of 10-25 times by the flexible plate 45, and the valve inner cylinder 63 is moved by that enlarged displacement part to change the passage area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow passage area variable mechanism for changing the flow passage area by expanding the displacement of a piezoelectric body using a displacement expanding mechanism and moving the valve by the expanded displacement.

[0002]

2. Description of the Related Art Recently, in many fields such as automobiles, industrial machines and plants, there is a demand for controlling the flow rate of fluids such as oil, air and cooling water with high precision and high speed (real time). The conventional solenoid valve has a problem in response and accuracy in changing the flow passage area. In order to satisfy both of the above, a piezoelectric actuator such as a piezoelectric element is known.

A piezoelectric body is suitable as a driving source because it expands and contracts with extremely high responsiveness to an applied voltage, but its displacement is extremely small. For example, even a laminated piezoelectric body formed by laminating about 100 disc-shaped piezoelectric bodies has a displacement of about several tens of microns, so the displacement is expanded and used in a practical stage.

An enlargement mechanism using the so-called Pascal's principle has been conventionally used as a mechanism for magnifying a minute displacement of the laminated piezoelectric material. This is to transfer the displacement of a piston with a large cross-sectional area driven by the expansion and contraction of a laminated piezoelectric material to a piston with a small cross-sectional area via hydraulic oil, and expand it to a displacement corresponding to the cross-sectional area ratio. (For example, refer to “Hydraulic switching valve equipped with piezoelectric actuator” in Japanese Patent Laid-Open No. 1-312283). This allows
A displacement of the laminated piezoelectric substance of several tens of microns can be obtained from a piston having a small sectional area as a displacement of about 1 mm. A valve or the like was moved by this small cross-sectional area piston to change the flow passage area.

[0005]

However, in the conventional example in which the above-mentioned laminated piezoelectric body and the displacement magnifying mechanism are combined, a displacement magnifying mechanism using the principle of Pascal is provided in addition to the flow channel area varying mechanism. And they both have a fine structure. In the conventional displacement magnifying mechanism, a cylinder and piston that minimize oil leakage are used.
Even if the hydraulic oil in the cylinder leaks out, the stroke of the small cross-sectional area piston, which originally has a displacement of about 1 mm, is reduced, and normal switching operation cannot be performed.

Therefore, it is necessary to provide a check valve mechanism for compensating the outflow of hydraulic oil from the inside of the cylinder, and to supply oil into the cylinder through the check valve when the hydraulic oil in the cylinder is insufficient. The structure became complicated, leading to higher costs. Further, even if the displacement of the laminated piezoelectric body is controlled by the applied voltage or the like, the valve position cannot be fixed because of the leakage of the hydraulic oil, so that the flow passage area cannot be continuously switched to the optimum state. ,
The controllability was poor.

Further, since the magnification of displacement is determined by the cross-sectional area ratio between the piston having a large cross-sectional area and the piston having a small cross-sectional area, the cross-sectional area ratio also needs to be 30 times in order to obtain a magnification of 30 times, for example. There is. Therefore, a small cross-sectional area piston and a large cross-sectional area piston having a cross-sectional area 30 times larger than that are required, and the size of the piston with a small cross-sectional area cannot be extremely reduced. Will also grow.

In view of the above, the present invention has a simple structure, and the required space can be made relatively small, while the variable width of the flow passage area can be set large, and the flow passage area can be set with respect to the stroke of the piezoelectric body. An object of the present invention is to provide a flow path area variable mechanism that can change linearly.

[0009]

In order to solve the above-mentioned problems, the flow path area varying mechanism of the present invention is characterized in that a flow path groove forming a part of a fluid passage is formed in an outer cylinder of a valve. A flow passage area variable mechanism that can change the opening state of the flow passage groove by sliding the valve inner cylinder that is inscribed in the valve outer cylinder in the axial direction to change the flow passage area according to the applied voltage. It is driven by a piezoelectric body that expands and contracts in response to the sliding member and is slidable in the expansion and contraction direction of the piezoelectric body, and is formed in a flat plate shape and is substantially parallel to the sliding direction of the sliding member. The valve inner cylinder is provided with a flexible plate having a fixed position and the other end abutting on the sliding member, and having an elastic deflection plate arranged so as to cause an initial deflection when the piezoelectric body is not applied. Can be moved in the bending direction by contacting the bending center of the bending plate. With placing, the shape of the flow path grooves, the flow passage area relative to the stroke of the piezoelectric body is characterized by being configured to vary linearly.

[0010]

According to the flow path area varying mechanism of the shock absorber of the present invention, when the piezoelectric body is expanded by applying a voltage, the sliding member slides in the sliding direction of the piezoelectric body, and the sliding member moves. The end of the pressed flexible plate that is in contact with the sliding member approaches the other end. By shortening the distance between the both ends in this way, the flexible plate further flexes toward the side where the initial flexure has occurred, and moves the valve inner cylinder in the axial direction. When the valve inner cylinder moves in the valve outer cylinder, the opening state of the flow path groove changes and the flow path area changes, but the flow path area changes linearly with the stroke of the piezoelectric body. Therefore, the flow path area can be continuously switched to the optimum state by controlling the applied voltage, and the controllability is improved.

On the other hand, when the voltage application is stopped, the piezoelectric body returns to its original state, and the flexible plate returns to its original initial flexible state due to its elastic restoring force. Along with this, the valve inner cylinder also returns to its original position, and the flow path area also returns to its original state. Here, the relationship between the displacement at which the distance between both ends of the flexible plate is shortened and the amount of flexure of the flexible plate, that is, the displacement magnification rate will be described. First, the deflection plate is assumed to be a part of a circular arc, and the displacement magnifying power k1 will be described with reference to FIG. The radius of curvature in the initial flexure state (indicated by the symbol a in the figure) is R,
Assuming that the radius of curvature after the linear distance between both ends of the arc is shortened by the displacement Δx (indicated by the symbol b in the figure) is r and the displacement of the center of the arc is k1Δx, From the geometrical relationship shown in A), the displacement magnifying power k1 is expressed by the following equation.

[0012]

[Equation 1]

FIG. 6B is a graph showing the relationship between the radius of curvature R and the angle θ in FIG. 6A and the displacement enlargement factor k1 when the displacement Δx = 0.025 mm. As you can see from this graph, when it is regarded as an arc,
A magnification of up to about 20 times can be obtained.

Next, the displacement magnifying power k2 in the case where the degree of deflection near the center of the flexible plate can be approximated by a triangle, as in the case where the degree of deflection is larger than other portions, will be described with reference to FIG. 7 (A). After the initial deflection state (indicated by the symbol c in the figure), the linear distance between both ends is shortened by the displacement Δx (the symbol d in the figure).
Indicate. ), Where k2 · Δx is the displacement of the central portion, the displacement enlargement factor k2 is calculated from the geometrical relationship shown in FIG.
It is expressed as the following equation.

[0015]

[Equation 2]

[Delta] x = 0.025 mm, L = 20
FIG. 7B is a graph showing the relationship between the angle θ and the displacement magnifying power k2 in FIG. 7A when mm is set. As can be seen from this graph, when it is regarded as a triangle, 2
A magnification of up to 5 times can be obtained.

As described above, since the minute displacement of the piezoelectric body is magnified by the flexure plate and the flexure of the flexure plate moves the valve inner cylinder to change the flow passage area, the required space is relatively small with a simple structure. Although it can be made extremely small, a sufficient displacement expansion rate can be obtained, the variable width of the flow passage area can be set large, and the flow passage area can be changed linearly with respect to the stroke of the piezoelectric body, improving controllability. It is possible.

[0018]

EXAMPLES Examples of the present invention will be described below. Figure 1
2 is a sectional view of the flow path area varying mechanism of the present embodiment, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a sectional view taken along the line BB of FIG.

As shown in FIG. 1, a substantially cylindrical first housing 17 is screwed into the lower end of the hollow cylinder 15,
A substantially cylindrical second housing 18 is screwed onto the lower end of the first housing 17. In the cylinder 15, a multi-layer piezoelectric body 27 and a first piston 30 that contacts the lower end of the multi-layer piezoelectric body 27 are sequentially installed.

Further, in the central portion of the first housing 17,
A partition portion 26 having a slide hole 24 through which the slide protrusion 30a of the first piston 30 can slide is provided. The first piston 30 is arranged such that the preset spring 35 is sandwiched between the first piston 30 and the partition portion 26, and the sliding protrusion 30 a is inserted into the sliding hole 24. Preset spring 35
Is installed in a pressurized state, and the first piston 30
It is a disk-shaped spring that applies a pressing force to the laminated piezoelectric body 27 via the.

A second piston 40 as a sliding member in the present invention, a variable valve portion 70, a fixed base 43, and a flexible plate 4 are provided on the opposite side of the laminated piezoelectric body 27 with the partition portion 26 interposed therebetween.
5, the end rod 48 and the like are stored. The second piston 40 has a substantially disk shape, and the first housing 1
It is slidable in the axial direction along the inner circumference of 7.

The flexible plate 45 is made of a spring steel plate or the like and has a rectangular plate shape. The flexible plate 45 has a central portion between the second piston 40 and the collar portion 44 provided at the lower portion of the fixed base 43 in advance. It is sandwiched in a slightly bent state. The flange portion 44 is provided with an engagement groove 44a for positioning the end portion of the flexible plate 45. In this embodiment, as shown in FIG. 4 (A), the end surface of the flexible plate 45 and the bottom of the engagement groove 44a are formed in a curved shape, and the flexible plate 45 itself swings with the end surface of the flexible plate 45 as a fulcrum. It is easy to move. On the other hand, as shown in FIG. 4 (B), the second piston 40 is also provided with a similar engaging groove 40a, and the engaging groove 40a and the end surface of the flexible plate 45 to be engaged are also curved. There is.

Here, a method of giving an initial deflection to the deflection plate 45 will be described. In this embodiment, a screw is formed on the outer circumference of the end rod 48, and the end rod 48 can be screwed in from the lower end of the first housing 17. Since the fixed base 43 is only placed on the end rod 48, when the end rod 48 is screwed in, the distance between the second piston 40 and the flange portion 44 of the fixed base 43 becomes shorter, so The plate 45 can be bent.

Next, the structure of the variable valve section 70 and its surroundings will be described. A valve holder 71 having a semi-cylindrical groove is fixed on the fixed base 43. The valve holder 71 has spacers 72 on both sides as shown in FIG.
It is sandwiched between. A cylindrical valve outer cylinder 60 is fixed so as to fit in the groove of the valve holder. A flow passage groove 77 is formed in the inner periphery of the valve outer cylinder 60 near the center thereof. The shape of the flow channel 77 will be described later in detail.

A through hole 73 through which hydraulic oil passes is provided at the bottom of the groove of the valve holder 71 described above, and communicates with a vertical hole 53 provided along the axial direction of the fixed base 43. A communication hole 79 that communicates with the through hole 73 is provided in the flow path groove 77 of the valve outer cylinder 60.

On the other hand, the valve outer cylinder 60 has an outer diameter slightly smaller than the inner diameter of the valve outer cylinder 60 (clearance is about 1 to 6 μm), and the inner circumference of the valve outer cylinder 60 is along the axis. A valve inner cylinder 63 that is freely slidable is arranged. The tip of the shaft portion 65 of the valve inner cylinder 63 is brought into contact with the central portion 45 a of the flexible plate 45.

The valve outer cylinder 60 has a shaft portion 65.
A flange portion 67 for receiving a return spring 81, which will be described later, is provided on the opposite side of the. And the valve outer cylinder 6
Of the two openings 0, the opening on the side opposite to the side on which the flexible plate 45 is arranged is closed by a substantially U-shaped fixing plate 83, and both ends of the fixing plate are in the second housing. It is in contact with the inner circumference of 18.

Therefore, the valve inner cylinder 63 is biased toward the flexible plate 45 side by the reaction force of the return spring 81, and its movement is restricted while being pressed near the apex of the flexible plate 45. It should be noted that when no voltage is applied to the laminated piezoelectric body 27, the flow passage groove 77 is formed by the valve inner cylinder 63.
Is in a fully closed state where all are closed.

The basic operation of the flow path area varying mechanism will be described. When a voltage is applied to the laminated piezoelectric body 27, the laminated piezoelectric body 27 generates a displacement proportional to the stored charge amount. When the laminated piezoelectric body 27 expands, it depresses the first piston 30 against the preset spring 35. Normally, the second piston 40 is pressed against the first piston 30 by the bending force of the flexure plate 45, so that the second piston 40 is pushed down in the axial direction by the displacement of the laminated piezoelectric body 27 in synchronization with the movement of the first piston 30. To be

Therefore, the second piston 40 and the fixed base 4
The distance between the rib portion 3 and the collar portion 44 becomes shorter, and the flexible plate 45
Bends further inward than the initial flexed state. In this case, the bending amount of the central portion 45a of the bending plate is equal to that of the laminated piezoelectric body 2
The displacement is enlarged 10 to 25 times with respect to the displacement of 7. The principle of this displacement enlargement has already been described in the above-mentioned “Operation” section, and thus detailed description thereof will be omitted.

When the central portion 45a of the flexible plate 45 moves inward, the valve inner cylinder 63 also moves to the fixed plate 83 side, and the flow path groove 77 opens. Then, for example, a fluid such as hydraulic oil that has flowed into the valve inner cylinder 63 from the upper chamber side through the opening portion 18a of the second housing 18 passes through the flow passage groove 77 through the communication hole 79, the through hole 73, and the vertical hole 53 in order. , And flow out to the lower chamber side.

Here, the shape of the flow channel 77 will be described in detail. First, the stroke of the laminated piezoelectric body 27 is X,
If the amount of deflection of the central portion 45a of the flexible plate 45 is L,
The relationship between X and L can be approximated as L = α · ln (x + 1) (1). However, α is a stroke range of the laminated piezoelectric body 27, and is a constant determined by the length of the flexible plate 45, the radius of curvature of the initial deflection, and the like. In the above formula (1), since L and X do not have a linear relationship, the flow passage area S due to the flow passage groove 77 cancels the non-linearity between them and the stroke X and the flow passage area S of the laminated piezoelectric body 27. It is an object of the present invention to make the and have a linear relationship.

The conditions satisfied by the flow path groove 77 will be described below. First, the flow path area S is a shaded portion in FIG. 5A is a vertical cross-sectional view of the valve outer cylinder 60, and FIG. 5B is an explanatory view schematically showing a horizontal cross-section of the portion where the flow path groove 77 is formed. However, in both cases, in order to facilitate understanding of the shape of the flow channel 77, the dimensions and the like are different from those shown in FIG.

Here, consider a cylindrical coordinate system in which the Z axis is the center line of the valve outer cylinder 60. In FIG. 5A, it is assumed that the flow path is fully closed when Z = Z0 and fully opened when Z = Z1. For simplification of the equation, Z0 = 0 and Z1 = L. In FIG. 5B, assuming that the inner diameter of the valve outer cylinder 60 is r, the depth of the flow channel groove 77 is h, and the central angle of the sector formed by the apex ABCD that is half the flow channel area S is θ, The central angle θ is the vertex A
Considering the BCD trajectory, it is obtained as a function of Z as follows.

A: r = r + h, θ = π (e ^Z −1) / (e ^L −1), Z = Z (2) B: r = r + h, θ = 0, Z = Z (3) C: r = r, θ = 0, Z = Z (4) D: r = r, θ = π (e ^Z −1) / (e ^L −1), Z = Z (5) Further, FIG. 5 (B), the vertex A with respect to the line segment BC,
B and symmetrical vertices a, Given b, a: r = r + h, θ = -π (e Z -1) / (e L -1), Z = Z ... (6) d: r = r, θ ^{= -π (e Z -1) /} (e L -1), the Z = Z ... (7). Therefore, the above (2), (5), (6), (7)
By forming the flow passage groove 77 in a fan shape having the vertices A, a, d, and D that satisfy the condition of the expression, the linear relationship between the stroke X of the laminated piezoelectric body 27 and the flow passage area S is satisfied. .

In this way, the minute displacement of the laminated piezoelectric element 27 is enlarged by the bending plate 45, and the valve inner cylinder 63 is moved by the bending of the bending plate 45 to change the flow passage area S. Although the required space can be relatively reduced by the configuration, a sufficient displacement expansion rate can be obtained and the flow rate control width can be increased. Furthermore, the channel groove 7
In No. 7, since the flow passage area S changes linearly with respect to the stroke of the laminated piezoelectric body 27, flow rate control can be easily realized.

The present invention is not limited to the embodiments described above, and can be carried out in various modes without departing from the scope of the present invention. For example, if the thickness of the central portion of the flexible plate 45 is reduced, the degree of bending of the central portion 45a of the flexible plate 45 is further increased, and it becomes closer to the triangular approximation, and a larger displacement enlargement ratio can be obtained. In addition, the flexible plate 4 is not made thin.
Even if the width of 5 is reduced, the same effect can be obtained.

[0038]

As described above, according to the flow path area varying mechanism of the present invention, the minute displacement of the piezoelectric body is enlarged by the flexure plate, and the valve inner cylinder is moved by the flexure of the switching flexure plate. Since the flow passage area is changed, the required space can be made relatively small with a simple structure, but a sufficient displacement expansion rate can be obtained, the flow control width can be made large, and the stroke of the piezoelectric body can be increased. On the other hand, since the flow path area is configured to change linearly, the flow rate can be easily controlled.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a channel area variable mechanism according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

3 is a sectional view taken along line BB of FIG.

FIG. 4A is a cross-sectional view showing an engagement state between a fixing stand collar portion and a flexible plate, and FIG. 4B is a cross-sectional view showing an engagement state between a second piston and the flexible plate.

FIG. 5A is a vertical cross-sectional view of a valve outer cylinder, and FIG.
It is explanatory drawing which showed typically the cross section of the part in which the flow path groove is formed.

FIG. 6A is an explanatory diagram showing a geometrical relationship when a flexible plate is approximated by a circular arc, and FIG. 6B is a graph showing a relationship between a radius of curvature R and an angle θ, and a displacement magnifying power k1.

7A is an explanatory diagram showing a geometrical relationship when a flexible plate is approximated by a triangle, and FIG. 7B is a graph showing a relationship between an angle θ and a displacement magnifying power k2.

[Explanation of symbols]

17 ... 1st housing, 18 ... 2nd housing, 2
Reference numeral 7 ... Multilayer piezoelectric body, 30 ... First piston, 30a ... Sliding protrusion, 35 ... Preset spring, 40 ... Second piston, 40a ... Engaging groove, 43 ... Fixing base,
45 ... Deflection plate, 45a ... Central part, 6
0 ... Valve outer cylinder, 63 ... Valve inner cylinder, 70 ... Variable valve part, 71 ... Valve holder, 73 ... Through hole,
77 ... Flow path groove, 79 ... Communication hole, 81
… Return spring, 83… Fixed plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junji Moriwaki 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. A flow path groove formed in an inner periphery of a flow path groove forming a part of a fluid passage, wherein a flow path is formed by axially sliding a valve inner cylinder inscribed in the valve outer cylinder. A flow path area variable mechanism capable of changing the flow path area by changing the opening state of the groove, which is driven by a piezoelectric body that expands and contracts according to an applied voltage, and is slidable in the expansion and contraction direction of the piezoelectric body. The sliding member is formed in a flat plate shape and is substantially parallel to the sliding direction of the sliding member. One end of the sliding member is fixed in position and the other end is brought into contact with the sliding member. And an elastic flexible plate arranged so as to generate an initial flexure in the non-applied state, the valve inner cylinder is brought into contact with the flexible center of the flexible plate to be movable in the flexible direction. , The shape of the flow path groove to the stroke of the piezoelectric body Flow area varying mechanism, characterized by being configured such that the flow area varies linearly Te.