JPH02125480A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To prevent a noise when a piezoelectric actuator is operated and the slip of a plunger by providing current control means for converting a voltage controlled by a triangular wave generator into a current in a driving circuit, and driving a stroke piezoelectric element with a triangular driving current. CONSTITUTION:A constant-voltage power source Sa is connected to a piezoelectric element (g) through switching elements S1, S2 and current controllers K3, L3. A triangular current controlled by the elements K3, L3 is fed to the element (g), which is elongated or contracted at a smooth equal acceleration. Since the element (g) is elongated or contracted at the smooth equal acceleration, noise is sufficiently suppressed, a slip between the plunger and clamping members (k), (l) is prevented, the operation of a piezoelectric actuator A becomes effective and heat generation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a piezoelectric actuator used to operate various devices.

(B) Conventional technology Conventionally, as one form of piezoelectric actuator, a plunger that moves in the axial direction, a clamp member that grips the plunger, a piezoelectric element that operates the clamp member, and a stroke piezoelectric element that moves one plunger are used. The piezoelectric element is actuated by a pulsed driving voltage to move one lange, and the piezoelectric element is applied with a driving voltage from a constant voltage power source through a switching element. It is configured.

(c) Problems to be Solved by the Invention However, although the operating amount of a piezoelectric element is proportional to the amount of electricity charged in the same piezoelectric element, in the above configuration, the driving current for charging the piezoelectric element is As shown in the figure, the waveform of the drive current becomes spike-like, the rise of the drive current is steep, and as shown in the figure, the acceleration of the piezoelectric element becomes excessive, generating noise, and the plunger slips. It has the disadvantage of being easy to do.

In order to solve this drawback, one idea was to install a constant current circuit in the drive circuit to keep the drive current for charging the piezoelectric element constant as shown in Figure 11, thereby suppressing the noise generation. Although this also suppressed the excessive operating acceleration caused by the spike-like drive current, as shown in the figure, the operating acceleration when the switching element was turned on and off was large enough to cause noise generation. and plunger slippage.

(d) Means for Solving the Problems The present invention includes a langeer that can move forward and backward in the axial direction within the casing, a stroke piezoelectric element, and a clamp piezoelectric element that clamps the plunger via a clamp member. , a piezoelectric actuator in which one langeer is moved forward and backward by a pulsed drive voltage, the drive circuit is provided with a current control means for converting the voltage controlled by the triangular wave generation circuit into a current, and at least a stroke piezoelectric element is provided. It is an object of the present invention to provide a piezoelectric actuator characterized in that it is configured to be driven with a triangular wave-shaped drive current.

(e) Functions and Effects In the present invention, by providing a current control means in the drive circuit, the waveform of the drive current that charges the piezoelectric element is controlled into a triangular waveform, and the absolute value of the acceleration of the piezoelectric element operation is kept constant. This makes it possible to prevent noise generation and one-lunger slip when the piezoelectric actuator operates.

(F) Examples The present invention will now be described in detail based on examples shown in the accompanying drawings.

FIG. 1 shows the overall configuration of a piezoelectric actuator (A) according to this embodiment.

As shown in the figure, (A) is a cylindrical case (c) having front and rear walls (g) and (b), in which a langeer (P) is installed concentrically and movably back and forth along the axis. , furthermore, 1
A pair of clamping piezoelectric elements (e) and (f) each having a clamp member (k) (+) and a stroke piezoelectric element (Q) are arranged concentrically on the outer peripheral surface of the langeer (P). It is composed of:

That is, the piezoelectric element for clamping (e) is connected to the case (c).
It is installed and supported on the left side of the holder (H), which is attached with a bolt (h), and on the - side, a piezoelectric element for clamping (, f) and a piezoelectric element for stroke (0).
is arranged and supported on the right side of the holder (H).

Next, the structure and operation of each piezoelectric element (e), (f), and (g) will be explained.

When the piezoelectric elements (e) and (f) are not energized, the clamping members (k) (+) clamp the plunger (P) with a constant clamping force, and when a negative voltage is applied, the clamping force increases. However, when a positive voltage is applied, the clamp is released.

On the other hand, the piezoelectric element (g) shortens in the axial direction on the plunger (P) when a positive voltage is applied, and expands when a negative voltage is applied.

In addition, Fig. 2 shows a piezoelectric actuator (
The configuration of a control device (c) for controlling A) is shown.

The control device (c) includes a microprocessor (R) and an A/
D, consists of an input/output interface (1) (0) consisting of a D/A converter, etc., and a memory (U) that stores a drive order program for the piezoelectric elements (e), (f), and (g), and Based on the input signal from the sensor (S) or switch (st+) inputted through the interface (1), a control signal is outputted according to the drive program described above.Through the interface (0), the piezoelectric element (e) (f) It is configured to output to the drive circuit (D) connected to (g).

Next, the movement of the plunger (P) by the actuator (A) having such a configuration will be explained with reference to FIGS. 3 to 6.

When a drive signal is input to the control device (c) from the sensor (S) or switch (needle) shown in FIG.
), as shown in FIG. 3, a negative voltage is applied to the piezoelectric element (f) to clamp the plunger (P), and then the piezoelectric element Ce
) to release the clamp on the plunger (P).

Next, as shown in Figure 4, when a positive voltage is applied to the piezoelectric element (g) to cause it to contract, the piezoelectric element (g) moves in the direction of the arrow, and as a result, the piezoelectric element (f) The clamping plunger (P) also moves in the direction of the arrow.

Thereafter, as shown in FIG. 5, a negative voltage is applied to the piezoelectric element (e) to clamp the first runge (P), and then a voltage is applied to the piezoelectric element (f) to clamp the first runge (P). Release the clamp.

Then, as shown in FIG. 6, when a negative voltage is applied to the piezoelectric element (g) to cause it to expand, only the piezoelectric element (f) moves in the direction of the arrow, returning to the state shown in FIG. 3.

After that, by repeating the above operation, the plunger (
P) can be moved in a linear manner with a stroke on the μm order or sub-μm order, and various devices and machines can be operated precisely.

In the present invention, such a piezoelectric actuator (A)
The drive circuit (D) is provided with current control means.

FIG. 7 shows a drive circuit (D) for a piezoelectric element (g) as an example.
It shows.

(K3) (L) (1) in the figure is a current control means,
A triangular wave generating circuit (K3) (LIHLl) connected to the output interface (0) of the control device (c), and an operational amplifier (K3) having a non-inverting input terminal connected to the triangular wave generating circuit (K3) (L1) (Ll). (L2) (L2) To, Mo
Current control element (K3) (L3) ([3
). In addition, operational amplifier (K3) (L
2) The inverting input terminal of (L2) is the current control element (K3)
(L3) Resistor (R
) (R) is interposed between the resistor (R) (R) and the current control element (K3) (L3) (13).

In addition, (Sa) is a constant voltage power supply, (sl) (s2) is a switching element, and the switching element (Sl) and current control element (K3) (L3
) is 0N (OFF>, the switching element (S2)
The circuit is switched so that the current control element ([3)] is turned OFF (ON), and voltage is alternately applied to the piezoelectric element (Q) from the forward and reverse directions.

In this way, the piezoelectric element (g) has a switching element (s
l) (s2) and current control element (K3) (L3) (13)
The piezoelectric element (g) is connected to the constant voltage power supply (Sa) via the current control element (K3) (L3) (
A triangular wave-shaped current as shown in FIG. 8 controlled by step 13) flows into the piezoelectric element (g), causing the piezoelectric element (g) to expand and contract with a gentle uniform acceleration as shown in FIG.

As mentioned above, since the piezoelectric element (g") performs the expansion and contraction operation with a gentle constant acceleration, the generation of noise is sufficiently suppressed, and furthermore, the plunger (P) and the clamp member (kHl)
This prevents slippage between the piezoelectric actuators (A), ensures reliable operation of the piezoelectric actuator (A), and prevents heat generation.

Note that the above drive circuit (b) can also be used for the piezoelectric elements (e) and (f) for clamping.

Next, a hot water mixing device (B) incorporating the piezoelectric actuator of the present invention will be described.

Figure 9 shows a hot water mixing device CB), in which a hot water supply pipe and a water supply pipe are connected to the inlets of the hot water side and water side flow rate adjustment valves (yl) (V2), respectively, and the answer valves (Vl) (V2) The flow rate ratio and the sum of the flow rates of the hot water and water supplied from the hot water supply pipe and the water supply pipe are determined by arranging the outlet ports of the water supply pipes so as to face each other and communicating with each other.
Adjust with the hot water side and water side flow rate adjustment valves (Vl) (V2),
The set temperature and flow rate are maintained.

The hot water side and water side flow rate regulating valves m) (V2) are configured as follows, except that the fluids passing through them are different for hot water and hot water.

That is, an inflow pipe (2) (2) is formed on the negative side of the main body (1), an outflow pipe (3) is formed on the other side, and the outflow pipe (3) is formed at the intersection with the inflow pipe (2) (2). Extend into the inside of the tube (3
) are formed with main valve seats (4) (4) on the end faces of the same main valve seats (4).
) (4) A diaphragm (5) (5) is stretched over the upper end surface of the inflow pipe (2) (2), and a pilot valve seat (6) is installed in the center of the diaphragm (5) (5). ) (6), orifices (7) (7) are provided on the same peripheral edge to communicate with the outflow pipe (3) and inflow pipe (2) (2), respectively, and the upper part of the diaphragm (5) (5) is Actuator mounting base (
8) (8) to form pressure chambers (9) (9) between the base (8) (8) and the diaphragm (5H5).

The above-mentioned piezoelectric actuator (AI) (A2) is arranged on the top surface of the actuator mounting base (8) (8), and the plunger (
By operating the diaphragm (5) (5) by bringing the valve body (11) (11) extending from (P) into contact with and separating from the pilot valve M (6) (6), the main valve seat (4)
(4) and the lower surface of the diaphragm (5) (5) are brought into contact with and separated from each other to open and close the hot water side and water side flow rate regulating valves (Vl) (V2).

Then, each actuator (A1) (A2) is operated based on the detected value of the temperature sensor (12) provided in the outflow pipe (3) to adjust the temperature of the mixed hot water discharged from the outflow pipe (3).
It is configured to control to a preset target temperature.

As mentioned above, in the hot water mixing device (8), the plunger is operated at a uniform acceleration, so noise generation and slip of the plunger are suppressed, so the operation is quiet and accurate. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram of a piezoelectric actuator according to the present invention, FIG. 2 is a block diagram showing the configuration of a control device, and FIGS.
Fig. 6 is an explanatory diagram of the operation of the actuator, Fig. 7 is a drive circuit diagram, Fig. 8 is a graph of the waveform of the drive current and the actuation acceleration of the piezoelectric element, and Fig. 9 is a hot water mixture equipped with the piezoelectric actuator according to the present invention. Cross-sectional explanatory diagram of the device, Figures 10 to 1
FIG. 1 is a graph of the drive current waveform and the actuation acceleration of the piezoelectric element according to the prior art. (A): Piezoelectric actuator (c): Gate (K3) (L01): Current control means P Nib plunger D = Drive circuit e (f): Piezoelectric element for clamping g = Piezoelectric element for stroke k (1): Clamp member Kl)(11): 3)(+3) in the triangular wave generation path: Current control element

Claims (1)

[Claims] 1) A plunger (
P), a piezoelectric element for stroke (g), and piezoelectric clamping elements (e) and (f) for clamping the plunger (P) via clamp members (k) and (l), and has a pulse-like drive. In the piezoelectric actuator (A), which moves the plunger (P) forward and backward by electric current, the drive circuit (D) has a current control element (K3) (L3) controlled by a triangular wave generation circuit (K1) (L1). A piezoelectric actuator comprising current control means (K) and (L) configured to drive at least a stroke piezoelectric element (g) with a triangular drive current.