JPH05122948A - Electrostatic motor - Google Patents

Abstract

PURPOSE:To select appropriate electrode pitch, electrode width and gap between stator and movable element to obtain a thrust near to the maximum thrust by setting the ratio of the electrode width to electrode pitch to 0.05-0.5 and that of the gap between stator and movable element to electrode pitch to 0.01-0.4 in an electrostatic motor of multipolar structure. CONSTITUTION:In the drive of an electrostatic motor of multipolar three-phase structure, when voltage is first applied to e.g. S-phase, a force acts on the electrodes M5-M7 of a movable element facing S-phase electrodes S1-S3 and on other electrodes M1-M4 and M8-M11 and the movable element moves until the S-phase electrodes and the electrodes of the movable element are arranged almost completely. Then, when voltage is applied successively to T-phase and R-phase, the movable element moves consecutively. In this case, when the ratio of an electrode width to electrode pitch is set between 0.05-0.5 and a gap between stator and movable element to electrode pitch, between 0.01-0.4; a large thrust can be obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrostatic motor applied to a fine actuator.

[0002]

2. Description of the Related Art The principle of an electrostatic motor is that when a stator and a mover have a pair of electrodes, when an applied voltage V is applied between the two electrodes, a horizontal thrust F ₀ is generated in the mover to drive the mover. To do. This thrust F ₀ is given by, for example, the mathematical expression (1) (WSNTrimmer, KJGabriel; "DESIGN CONSID
ERATION FOR A PRACTICAL ELECTRO STATIC MICRO MOTO
R ", Sensors and Actuators, 11 (1987) 189-206). F ₀ = εLV ² / 2G (1) where ε is the dielectric constant, L is the electrode length, and G is the gap between the stator and the mover. Since the thrust F due to the electric field is small, in order to obtain a large thrust, the electrode has a structure in which the electrodes have a width W and a pitch P as shown in FIG. 2 is a mover, 31, 32, ..., 41
42 indicates an electrode, and 5 indicates an insulating portion. G is the gap between the stator and the mover, P is the electrode pitch, and W is the electrode width. As shown in FIG. 2, the drive as the electrostatic motor is as shown in FIG.
Such a multi-pole structure has a three-phase structure in which the electrical angle is shifted by 120 ° (Japanese Patent Laid-Open No. 3-27783). The driving of this multi-pole three-phase structure is as follows. When a voltage is applied to the S phase, the S phase electrode S1
The force also acts on the electrodes M5 to M7 of the mover facing to S3 to S3, and the electrodes M1 to M4 and M8 to M11 other than the mover, so that the force of moving the mover to the left acts comprehensively. This force causes the mover to move to the left until the S-phase electrode and the mover electrode are substantially aligned. Next, by switching the applied voltage from the T phase to the R phase, the mover can be moved to the left one after another.

[0003]

However, in such a multi-pole structure, not only the facing electrodes but also a large number of electrodes on both sides influence the thrust, and the thrust cannot be simply calculated by the mathematical formula 1. For example, paying attention to the mover electrode 43, the thrust acting on this electrode portion is not limited to the facing stator electrode 33, but the left electrode 31, 32 right electrode 34,
Affected by 35. In addition, the degree of influence also depends on the electrode width W.
It is predicted that the gap G will change subtly. Therefore, an object of the present invention is to provide an electrostatic motor having a multi-pole structure in which the thrust is maximized by obtaining optimum conditions such as an electrode pitch, an electrode width, and a gap between a stator and a mover.

[0004]

Therefore, in an electrostatic motor having a multi-pole structure, therefore, the ratio of the electrode width W and the electrode pitch P (W
/ P) to be 0.05 to 0.5, and
The ratio (G / P) of the gap G between the stator and the mover and the electrode pitch P is set to 0.01 to 0.4.

[0005]

By selecting an appropriate electrode width and gap for the pitch, the influence of the electrodes on both sides of the stator or the electrodes on the facing surface is minimized, and a thrust close to the maximum thrust can be obtained.

[0006]

The present invention will be described in detail with reference to the drawings. FIG. 2 is a configuration diagram of an electrostatic motor used in the present invention, and shows a part of a structure having multipole electrodes on a stator and a mover. The conditions under which high thrust was obtained were calculated by numerical analysis simulation, and the actual thrust was confirmed based on this numerical value. The thrust F is represented by R ₁ in the mathematical expression (2) as a ratio with the thrust F _{0 in} the case of a pair of electrodes. R ₁ = F / F ₀ = F / (εLV ² / 2G) (2) The thrust ratio R ₁ is calculated by the electrode width W and the gap G by the interelectrode pitch P, as shown in equations (3) and (4). The relationship was investigated using the dimensionless values R ₂ and R ₃ . R ₂ = W / P (3) R ₃ = G / P (4) FIG. 3 shows R ₂ (W / P) when the pitch P is 20 μm.
It is the result of examining the relationship of R ₁ with respect to. As described above, R ₁ is the maximum value F of the thrust, and the thrust F ₀ when the pair of electrodes is F _0.
It is a value divided by, and takes R ₃ (G / P) as a parameter. The maximum thrust value is the maximum value when the mover moves by one pitch and the thrust changes as shown in FIG. 4 depending on the amount of movement. From Fig. 3, thrust ratio R ₁
Shows the largest value when R ₂ (W / P) is 0.2 to 0.3. Therefore, in designing, if R ₂ (W / P) is set between 0.05 and 0.5, I know it's good. Further, in FIG. 5, R ₂ (W / P) is 0.1, 0.3, 0.5.
In Fig. 5, the effect of R ₃ (G / P) was investigated.
It can be seen that the thrust ratio R ₁ increases as R ₃ decreases. Comparing thrust within a given dimension depends on how many electrodes are provided within that dimension. This is thrust F
Is divided by the pitch P, which can be evaluated by the mathematical expression (5). R ₄ = F / P (5) R ₁ of the formula (2) and R ₃ of the formula (4) are replaced with R of the formula (5).
Substituting into _4, R ₄ is the formula (6). R ₄ = εLV ² / 2G ² · (R ₁ R ₃ ) (6) From FIG. 5, the thrust ratio R ₁ can be expressed by the following equation (7): R ₁ = a ₀ · R ₃ ^a + b (7) become that way. Here, a ₀ , a, and b are constants. Substituting this into equation (6), R ₄ is given by equation (8). ^{_{R 4 = εLV 2 / 2G 2}} · {a 0 · R 3 (a + 1) + b · R 3} (8) where the values of R ₄ when used as a constant gap G, R ₄
Can be evaluated by the value R ₅ obtained by dividing by εLV ² / 2G ² . _{R 5 = R 4 / (εLV} 2 / 2G 2) (9) This R ₅ is the value of R ₃ (G / P) indicated by Equation (10), takes a maximum value with a curve convex upward. R ₃ = [− b / a ₀ · (a + 1)] ^{1 / a} (10) The results are shown in FIG. 6. Here, the values shown in Table 1 obtained from FIG. 5 were used for a ₀ , a, and b.

[0007]

[Table 1]

From this figure, R ₃ (G / P) has a maximum value near 0.1, and as a design guideline, R ₃ (G / P)
It can be seen that a relatively large thrust can be obtained by setting the value of between 0.01 and 0.4. Also, the designed stator,
There is also an effect of checking whether the specifications around the electrodes of the mover are close to optimal values.

[0009]

As described above, according to the present invention, an appropriate pitch, electrode width, and gap can be freely selected, so that an actuator with maximum thrust can be easily manufactured.

[Brief description of drawings]

1 is a model diagram of an electrostatic motor having multi-pole electrodes.

FIG. 2 is a model diagram of a three-phase drive electrostatic motor having multi-pole electrodes.

FIG. 3 is a relationship diagram of a thrust ratio R ₁ with respect to R ₂ (W / P) of the present invention.

FIG. 4 is a diagram showing changes in thrust ratio R ₁ with respect to the moving amount of a mover of the present invention.

FIG. 5 is a relational diagram of thrust ratio R ₁ with respect to R ₃ (G / P) of the present invention.

FIG. 6 is a relationship diagram of R ₅ with respect to R ₃ (G / P) of the present invention.

[Explanation of symbols]

1 Stator 5 Insulator 2 Mover G Gap between stator and mover 3 Stator electrode P Pitch between electrodes 4 Mover electrode W Electrode width

Claims (2)

[Claims] 1. A stator and a mover, each of which is provided with a plurality of electrodes each having an electrode width W and an electrode pitch P, are held at a constant gap G, and between the stator and the mover. ,
In an electrostatic motor driven by applying a voltage V, the ratio (W / P) of the electrode width W and the electrode pitch P is set to 0.05.
An electrostatic motor characterized in that the electrostatic motor is composed of 0.5 to 0.5. 2. A gap G between the stator and the mover,
The ratio (G / P) to the electrode pitch P is 0.01 to 0.4.
The electrostatic motor according to claim 1, wherein