JP3123248B2 - Channel area variable mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention enlarges the displacement of a piezoelectric body using a displacement enlarging mechanism, and moves the valve by the enlarged displacement to thereby increase the opening area of the flow passage (hereinafter simply referred to as flow passage area). The present invention relates to a variable channel area mechanism for changing.

[0002]

2. Description of the Related Art In recent years, in many fields such as automobiles, industrial machines, and plants, there is a demand for controlling the flow rate of fluid such as oil, air, and cooling water with high accuracy and at high speed (real time). In order to change the flow path area, the conventional solenoid valve has a problem in response and accuracy. Therefore, a device using a piezoelectric body such as a piezo element as an actuator has been known as a device that achieves both of the above.

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

[0004] An enlargement mechanism using the so-called Pascal's principle has been used as a mechanism for enlarging the minute displacement of the laminated piezoelectric body. This means that the displacement of a large-area piston driven by the expansion and contraction of a laminated piezoelectric body is transmitted to a small-area piston through hydraulic oil and expanded to a displacement corresponding to the cross-sectional area ratio. (For example, see “Hydraulic switching valve with piezoelectric actuator” in JP-A-1-313283). This allows
A displacement of the laminated piezoelectric body of several tens of microns can be obtained from a piston having a small cross-sectional area as a displacement of about 1 mm. The valve or the like is moved by the small cross-sectional area piston to change the flow area.

[0005]

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

For this reason, it is necessary to provide a check valve mechanism for compensating the outflow of hydraulic oil from the cylinder, and to supply oil into the cylinder via the check valve when the hydraulic oil in the cylinder runs short. The structure became complicated, leading to an increase in cost. Further, even if the displacement of the laminated piezoelectric body is controlled by an applied voltage or the like, the position of the valve cannot be fixed at a constant value due to the leakage of the hydraulic oil, so that the flow path area cannot be continuously switched to an optimal state. ,
Controllability was poor.

Further, since the enlargement rate of the 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 must be increased to 30 times in order to obtain an enlargement rate of, for example, 30 times. There is. Therefore, a small cross-sectional area piston and a large cross-sectional area piston having a cross-sectional area 30 times as large as the piston are required, and the size of the small cross-sectional area piston cannot be extremely reduced. Will also be large.

Accordingly, the present invention has a simple structure, and it is possible to set the variable width of the flow path area to be large while reducing the required space relatively, and to increase the flow path area with respect to the stroke of the piezoelectric body. It is an object to provide a channel area variable mechanism that can be continuously changed.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a variable-flow-path area mechanism according to the present invention comprises a flow passage capable of changing the opening area of the flow passage by moving a valve interposed in a fluid passage. A road area variable mechanism, which is driven by a piezoelectric body that expands and contracts in accordance with an applied voltage, is disposed in parallel with a sliding member that can slide in the expansion and contraction direction of the piezoelectric body, Two rod-shaped members abutting on the pressing direction side, an elastic flat plate-shaped flexible plate sandwiched between the two rod-shaped members, and the rod-shaped member sandwiched between the rod-shaped members and opposite to the sliding member. A slope provided so as to correspond to each of the members and opposed to each other, and to allow the rod-shaped members to approach each other when the rod-shaped member moves in a direction perpendicular to the axis; To bend in the direction of deflection With movably disposed, said deflection plate, at the time of non-application state to said piezoelectric body, characterized in that arranged so that the initial deflection occurs in the valve side.

[0010]

According to the channel area variable mechanism of the present invention, when the voltage is applied to expand the piezoelectric body, the sliding member slides in the sliding direction of the piezoelectric body and is pressed by the sliding member. The two rod-shaped members descend on the slope in a direction perpendicular to the axis, and the distance between the rods approaches each other. Therefore, the distance between both ends of the flexure plate is shortened, and the flexure plate flexes further to the side where the initial flexure has occurred, and presses and moves the valve. The opening area of the flow path can be changed by moving the valve.

On the other hand, when the application of the voltage is stopped, the piezoelectric body returns to the original state, and the flexible plate returns to the original initial bending state by its own elastic restoring force. Accordingly, the valve returns to the original position, and the flow path area returns to the original state. Here, the relationship between the displacement in which the distance between both ends of the flexible plate is shortened and the amount of deflection of the flexible plate, that is, the displacement enlargement ratio will be described. First, the deflection plate is assumed to be a part of a circular arc, and the displacement enlargement ratio k1 will be described with reference to FIG. Let R be the radius of curvature in the initial deflection state (indicated by the symbol a in the figure), and r be the radius of curvature after the linear distance between both ends of the arc has been reduced by the displacement Δx (indicated by the symbol b in the figure). If the displacement at the center of the arc is k1 △ x, the displacement magnifying power k1 is given by the following equation from the geometrical relationship shown in FIG.

[0012]

(Equation 1)

FIG. 5B is a graph showing the relationship between the radius of curvature R, the angle θ in FIG. 5A, and the displacement magnifying power k1 when the displacement Δx is 0.025 mm. As can be seen from this graph, when considered as an arc,
An enlargement factor of up to about 20 times can be obtained.

Next, with reference to FIG. 6 (A), the displacement enlargement ratio k2 when the degree of deflection near the center of the bending plate is larger than that of the other portions and when it can be approximated by a triangle will be described. From the initial deflection state (indicated by the symbol c in the figure), the linear distance between both ends is reduced by the displacement Δx (the symbol d in the figure).
Indicated by ) Is k2 · △ x, the displacement magnification k2 is given by the geometric relationship shown in FIG.
It is shown as the following equation.

[0015]

(Equation 2)

Then, Δx = 0.025 mm, L = 20
FIG. 6B is a graph showing the relationship between the angle θ and the displacement magnification k2 in FIG. As can be seen from this graph, when considered as a triangle, 2
An enlargement factor of up to about 5 times can be obtained.

As described above, since 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 flexure plate to change the flow path area, the required space is relatively simple and the required space is relatively small. However, a sufficient displacement magnification can be obtained, and the flow path area can be continuously changed.

[0018]

Embodiments of the present invention will be described below. FIG.
FIG. 3 is a cross-sectional view of a channel area variable mechanism according to one embodiment. As shown in FIG. 1, a substantially cylindrical first housing 17 is screwed to a lower end of the hollow cylinder 15, and a substantially cylindrical second housing 18 is further screwed to the lower end of the first housing 17.
Is screwed. In the cylinder 15, a laminated piezoelectric body 2 is provided.
7. First piston 3 abutting on lower end of laminated piezoelectric body 27
0 are built in in order.

In the center of the first housing 17,
A partition 26 having a sliding hole 24 in which the sliding protrusion 30a of the first piston 30 can slide is provided. The first piston 30 is disposed with the preset spring 35 interposed between the first piston 30 and the partition 26 and with the sliding protrusion 30 a inserted through the sliding hole 24. Preset spring 35
Is installed in a pressed state, and the first piston 30
This is a ring-shaped spring that applies a pressing force to the laminated piezoelectric body 27 through the.

On the opposite side of the laminated piezoelectric body 27 across the partition 26, a second piston 40 as a sliding member in the present invention, a rod-shaped member 43, a flexible plate 45, a cap 4
7. The valve 50 and the like are stored. Second piston 40
Is substantially disk-shaped, and is slidable in the axial direction along the inner periphery of the second housing 18.

The rod-shaped member 43 has a cylindrical shape as shown in FIG.
Are formed. On the other hand, the flexure plate 45 is made of a steel plate for a spring or the like and has a rectangular flat plate shape. Then, by attaching both ends of the flexible plate 45 so as to be inserted into the slits 43a, the flexible plate 45 is sandwiched between two rod-shaped members 43 arranged in parallel.

The cap 47 has a second
It is arranged on the opposite side of the piston 40 and has a ring-like shape.
It is screwed and fixed by two screws 49a and 49b. The shape of the cap 47 will be described in more detail with reference to FIG. FIG. 3A is a top view of the cap 47,
(B) is a sectional view taken along the line A-A, and (C) is a sectional view (B) of (A).
It is -B sectional drawing. The cap 47 has a substantially cylindrical shape, and is provided with two mutually facing inclined surfaces 48 having a width equal to or longer than the length of the rod-shaped member 43. The slope 48 of this embodiment is the same as that shown in FIG.
As shown in (B), each has an angle θ with respect to the axial direction.

The rod 43 is pressed by the lower surface of the second piston 40 and is pressed against the slope 48 of the cap 47. A projection 40 a having a length approximately equal to the radius of the rod-shaped member 43 is provided at the center of the lower surface of the second piston 40.
Is provided, and in a state where the rod-shaped member 43 is in contact with the lower surface of the second piston 40, the flexible plate 45 is
It serves as a stopper for preventing deflection to the zero side.

Referring back to FIG. 1, a valve 55 is disposed below the screws 49a and 49b. The valve 55 includes a shaft portion 55a and a valve body portion 55b, and the shaft portion 55a is inserted through the screws 49a and 49b and the cap 47.

The valve body 55b is urged toward the flexible plate 45 by a return spring 60, and the tip of the shaft portion 55a is connected to the flexible central portion 45 of the flexible plate 45.
The movement is restricted in the state of contact with a. The valve body 55b is slidable in the second housing 18 along the inner peripheral surface thereof, and the outer periphery thereof is sealed by an O-ring 57.

The valve main body 55b is provided with a valve-side flow path R1 so as to communicate the side surface and the lower surface thereof, while the second housing 18 communicates the inside and the outside. A housing-side flow path R2 is provided. The outside of the second housing 18 is connected to the upper chamber side, and the inside is connected to the lower chamber side. Therefore, when the two flow paths R1 and R2 communicate with each other, for example, the operating oil can flow from the upper chamber to the lower chamber.

In this embodiment, when no voltage is applied to the laminated piezoelectric element 27, the two flow paths R1 and R2 are not communicated, and the flow path area is set to "0". I have. Next, the operation of the present channel area variable mechanism will be described. When a voltage is applied to the multilayer piezoelectric body 27, the multilayer piezoelectric body 27 generates a displacement proportional to the stored charge amount. When the multilayer piezoelectric body 27 expands, the first piston 30 is pushed down against the preset spring 35.

Normally, the second piston 40 is
, The cap 47 is merely pressed against the first piston 30 by the reaction force from the slope 48 of the cap 47, so that the displacement x of the laminated piezoelectric body 27 in the axial direction is synchronized with the movement of the first piston 30. Only depressed.

Therefore, the two rod-shaped members 43 are pressed by the second piston 40 and respectively descend along the slopes 48 of the cap 47. Due to this lowering, the rod-shaped member 43 moves by a displacement y in a direction orthogonal to the moving direction of the second piston 40. The displacement y can be expressed as y = xtan θ using the displacement x and the angle θ of the slope 48 shown in FIG.

That is, the distance between the two rod members 43 approaches each other by 2y = 2 × tan θ, and the distance between both ends of the flexible plate 45 becomes shorter by the displacement 2y. Therefore, as shown in FIG. 2B, the flexure plate 45 flexes further to the side where the initial flexure occurred (the valve 55 side).
In this case, the flexure amount z of the flexure plate central portion 45a is enlarged to about 10 to 25 times the displacement enlargement ratio k with respect to the displacement 2y. The principle of the displacement enlargement has also been described in the above-mentioned section of “action”, so that detailed description will be omitted.

Accordingly, the relationship between the deflection z and the displacement x is
z = x · 2ktan θ, and at an angle θ = 45 deg,
The deflection z is about 20 to 50 times the displacement x. As described above, when the central portion 45a of the flexible plate 45 moves toward the valve 55, the valve 55 is urged downward to move, and the valve-side flow path R1 is moved to the housing-side flow path R.
Communicates with 2. Then, for example, the operating oil flowing from the upper chamber through the housing-side flow path R2 is guided into the second housing 18 from the valve-side flow path R1.
It flows out to the lower chamber side.

Then, the valve 55 moves by the amount of deflection Z, and the communication area between the two flow paths R1 and R2 can be changed.
The flow area can be continuously varied, and thus the flow rate can also be continuously controlled. As described above, the multilayer piezoelectric body 2
7 is enlarged by a simple structure such as the rod-shaped member 43 moving on the slope 48 and the flexure plate 45 sandwiched therebetween, and the valve 55 is moved by the flexure of the flexure plate 45 to change the flow path area. Therefore, while a required space can be relatively reduced with a simple configuration, a sufficient displacement enlargement ratio can be obtained, and control can be performed by continuously changing the flow path area.

Next, another embodiment will be described. FIG.
(A) shows a rod-shaped member 43 and a second piston 40.
And rollers 60 are interposed therebetween. By doing so, the rod-shaped member 43 rotates in the opposite direction to the rod-shaped member 43 at the time of operation, so that the rod-shaped member 43 rolls on the slope 48, and the loss due to friction between the second piston 40 and the slope 48. Is reduced. The rollers 60 may be provided between the rod 43 and the slope 48.

FIG. 4B shows an example in which the rod-shaped member 43 and the flexible plate 45 are integrated. In this case, the end of the flexible plate 45 is bent to form a cylindrical portion 45b so that the rod-shaped member 43 can be played. As described above, the present invention is not limited to such embodiments at all, and can be implemented in various modes without departing from the gist of the present invention. For example, if the thickness of the central portion of the flexible plate 45 is reduced, the central portion 45 of the flexible plate 45 can be reduced.
The degree of bending of “a” is further increased, and closer to triangular approximation, so that a larger displacement magnification can be obtained.
The same effect can be obtained by reducing the width of the flexible plate 45 instead of reducing the thickness.

When it is difficult to form the inclined surface 48 into a flat inclined surface as shown in FIG. 3, for example, a conical shape can be used. Further, in the present embodiment, an example in which the laminated piezoelectric body 27 is used as an actuator has been described. However, the same displacement enlargement is performed by another type of actuator such as a solenoid. However, it is more effective to use it for an actuator whose displacement is extremely small as a basic property like the laminated piezoelectric body 27.

[0036]

As described above, according to the variable channel area 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 path area is changed, the required space can be relatively reduced with a simple configuration, a sufficient displacement enlargement ratio is obtained, and the variable width of the flow path area can be set large. Further, since the flow path area can be continuously changed with respect to the stroke of the piezoelectric body, flow rate control can be easily realized.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a rod-shaped member and a flexible plate.

FIG. 3A is a top view of the cap, and FIG.
(A) is a sectional view taken along the line AA, and (C) is a sectional view taken along the line BB of (A).

FIG. 4 is a sectional view showing another embodiment.

FIG. 5A is an explanatory diagram showing a geometric relationship when a flexible plate is approximated by an arc, and FIG. 5B is a graph showing a relationship between a curvature radius R and an angle θ and a displacement magnification k1.

FIG. 6A is an explanatory diagram showing a geometric relationship when a flexible plate is approximated by a triangle, and FIG. 6B is a graph showing a relationship between an angle θ and a displacement magnification k2.

[Explanation of symbols]

R1: valve side flow path, R2: housing side flow path, 15: cylinder, 17: first housing, 18: second housing, 27: laminated piezoelectric body,
30: first piston, 40: second piston, 4
3 ... Bar-shaped member, 45 ... Flexible plate, 45a ...
The center (of the flexure), 47 ... cap, 48 ...
Slope, 55 ... Valve

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takehiro 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (56) References JP-A 1-312283 (JP, A) JP-A 63 JP-A-2-258606 (JP, A) JP-A-2-236606 (JP, A) JP-A-2-138250 (JP, U) JP-A-61-147405 (JP, U) JP-A-62-130274 (JP, U) ) Actually open 61-50448 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16K 31/02 H02N 2/00 F16F 9/44-9/50

Claims (1)

(57) [Claims] 1. A passage area variable mechanism capable of changing an opening area of the passage by moving a valve interposed in a fluid passage, the mechanism being driven by a piezoelectric body that expands and contracts in accordance with an applied voltage. A sliding member slidable in the direction of expansion and contraction of the piezoelectric body; two rod members arranged in parallel and abutting on the pressing direction side of the sliding member; and sandwiched between the two rod members. And a flat flexible plate having elasticity, and provided on the opposite side of the sliding member with the rod-shaped member therebetween so as to correspond to each of the rod-shaped members and face each other, and the rod-shaped member is provided with a shaft. And a slope that allows the rod-shaped members to approach each other when moved in the orthogonal direction.The valve is disposed so as to be movable in the bending direction by contacting the valve with the center of the bending of the bending plate. , Non-application to the above piezoelectric body During state flow area varying mechanism, characterized in that it arranged so that the initial deflection occurs in the valve side.