JP3010845B2 - Displacement detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A displacement detecting device according to the present invention detects a displacement of a moving body, such as a linear actuator, which moves along a moving path made of a magnetic body having fixed teeth formed at predetermined fixed pitches. This is for detecting and calculating the position and speed of the moving body from the displacement amount.

[0002]

2. Description of the Related Art For example, linear actuators and the like are mainly used in factories and the like related to semiconductors and biotechnology which dislike dust and the like. Therefore, in order to calculate the position and speed of the moving body of the linear actuator, the displacement detection device that detects the displacement of the moving body needs non-contact sensors as much as possible.

[0003] As such non-contact sensors, those applying light or magnetism are conceivable, but a structure is employed in which the fixed teeth or grooves between the fixed teeth are directly detected using the light or magnetism. In this case, it is difficult to detect the displacement of the moving body with an accuracy smaller than the fixed pitch of the fixed teeth. Therefore, some magnetic circuits are closed between the moving body and the fixed teeth, and displacement detection is performed using a resolver digital conversion circuit that calculates the relative displacement between the moving body and the fixed teeth from the phase difference between these magnetic circuits. The device is of interest. In order to obtain a magnetic circuit used in the resolver digital conversion circuit, for example, as shown in FIG. 15, each of a pair of magnetic pole teeth C and D excited to different polarities by exciting coils A and B is replaced with a different fixed tooth E. , That is, arranged in the direction perpendicular to the tooth traces of the fixed teeth E to form a magnetic pole pair F. Using two or more pairs of magnetic pole pairs F having the same characteristics, these are different from the fixed pitch P of the fixed teeth E. Arrange at the arrangement pitch. In the case of the figure, three pairs of magnetic poles F are arranged at an arrangement pitch 7/3 times the fixed pitch P. When, for example, a single-phase sine wave voltage is applied to these magnetic pole pairs F, each excitation coil A, B causes each magnetic pole pair F
Are excited in the magnetic pole teeth C and D of the N pole, and the lines of magnetic force generated from the magnetic pole teeth C of the N pole pass through the inside of the fixed tooth E and the magnetic pole teeth of the S pole
Return to At this time, since the arrangement pitch of the magnetic pole pairs F and the fixed pitch of the fixed teeth E are different, the areas of the fixed teeth E where the magnetic pole teeth C and D face each other and receive the magnetic field are different. Accordingly, the magnetic flux density passing through the fixed teeth E from the respective magnetic pole pairs F is different, and the inductances of the exciting coils A and B are different. Therefore, the current passing through the exciting coils A and B is not fixed. A phase difference occurs according to the magnetic field area of the tooth E.
The current including the phase difference is input to the resolver digital conversion circuit, a phase corresponding to the magnetic field area of the fixed tooth is obtained, and the displacement of each magnetic pole pair, that is, the relative displacement of the moving body with respect to the fixed tooth is detected from the phase. What you want to do.

As a displacement detecting device in which such a magnetic pole pair is arranged on a moving body, for example, Japanese Patent Application Laid-Open No.
Japanese Patent Application Publication No. -183961 or the one shown in FIG. Among them, FIG.
The displacement detection device shown in FIG. 1 has a resolver detection tooth G unique to the fixed tooth E separately arranged in parallel along the fixed tooth E, and is laterally moved from the moving body H so as to face the resolver detection tooth G. The magnetic pole pair F is disposed on the support portion J, and the resolver magnetic pole pair support portion J is projected. On the other hand, the displacement detection device shown in FIG. 14 projects a resolver magnetic pole pair support J in the direction of movement of the moving body H, that is, in a direction perpendicular to the tooth trace of the fixed tooth E. The magnetic pole pairs F are arranged side by side in the direction of movement of the moving body H.

[0005]

However, the conventional displacement detecting device has the following problems. 1. In the displacement detection device shown in FIG. 13, it is necessary to install the resolver detection teeth G in addition to the fixed teeth E, which not only increases the cost but also increases the supporter J and the magnetic pole pair on the resolver detection teeth G. Since F passes through, the space above the resolver detection teeth G becomes a so-called dead space, and the installation space of the entire linear actuator becomes large.

[0006] 2. In the displacement detection device shown in FIG. 14, a support J is protruded in the moving direction of the moving body H, and the magnetic pole pair F is arranged on the supporting part J in the moving direction of the moving body H. Therefore, the length of the entire moving body in the moving direction becomes longer. Further, when the magnetic pole pairs F are arranged side by side in the moving direction of the moving body H, there is a limit in shortening the arrangement pitch due to the size of the exciting coils C and D. The protruding length dimension becomes large. Therefore, when the installation space for the fixed teeth is limited, the actual moving distance of the moving body may be shortened.

[0007] 3. In any of the displacement detecting devices, the directions of the magnetic pole teeth C and D of the magnetic pole pair F are orthogonal to the tooth traces of the fixed teeth E, and the magnetic circuit is formed so as to straddle at least the adjacent fixed teeth E. However, when all the fixed teeth cannot be formed by one block of fixed teeth E due to a long installation length of the fixed teeth E, the fixed teeth E may be arranged side by side as shown in FIG.
Since a magnetic circuit is not formed at the joint between the fixed teeth E, it is difficult to detect the displacement.

The present invention has been developed in view of the above-mentioned problems, and has a small installation space for a linear actuator, does not impede the moving distance of a moving body, and has a small displacement even when fixed teeth are connected. It is an object of the present invention to provide a displacement detection device that enables continuous detection.

[0009]

The displacement detecting device according to the present invention is different from the displacement detecting device for a moving body which moves along a moving path made of a magnetic material having fixed teeth formed at predetermined fixed pitches. A pair of magnetic pole teeth excited in a polarity is arranged in the tooth trace direction of the fixed tooth to face the fixed tooth to form a magnetic pole pair, and two or more different magnetic pole pairs are arranged in the tooth trace direction of the fixed tooth. It is characterized by being arranged so as to be shifted in a direction perpendicular to the tooth trace. Further, the magnetic pole pair is
Magnetic pole pairs that are arranged side by side with the tooth traces of the fixed teeth in the orthogonal direction
Excitation of adjacent magnetic pole teeth to different polarities
The gap is characterized by being magnetically joined.
You.

[0010]

In the displacement detecting device according to the present invention, the pair of magnetic pole teeth excited in different polarities are arranged in the tooth trace direction of the fixed tooth so as to face the fixed tooth to form a magnetic pole pair. It is not necessary to separately install resolver detection teeth, and the magnetic circuit formed in the fixed teeth from the magnetic pole pair passes through only one fixed tooth without straddling at least the adjacent fixed teeth. Even when adjacent fixed teeth are separated like a seam of a tooth, displacement of the moving body can be continuously detected.

In addition, since two or more pairs of magnetic poles configured as described above are arranged in the direction perpendicular to the tooth trace of the fixed tooth while being arranged in the direction perpendicular to the tooth trace, for example, Also in the case where the support portion is protruded and the magnetic pole pair is disposed on the support portion, the size of protrusion of the support portion can be reduced.
For this reason, even when the installation space for the fixed teeth is limited, the moving distance of the moving body is not hindered. Also,
When the magnetic pole pairs are arranged in a direction orthogonal to the tooth traces of the fixed teeth,
Exciting adjacent magnetic pole teeth of a matching magnetic pole pair to different polarities,
Because the magnetic poles are magnetically joined between adjacent magnetic pole pairs,
Out of one pair of magnetic pole teeth excited to the N pole
Some of the magnetic field lines pass through the fixed teeth and
Return to the magnetic pole teeth excited to the S pole of the pole teeth,
The line of magnetic force deviated in the orthogonal direction from the tooth trace of the fixed tooth
Can be supplemented with magnetic pole teeth, preventing a decrease in overall magnetic flux density
When the moving body is moving at high speed,
The fluctuation of the magnetic circuit between the two can be compensated.

[0012]

FIG. 1 shows an embodiment of a displacement detecting apparatus according to the present invention, which is provided for detecting a displacement of a slider of a linear actuator moved by a linear motor. First, the structure of the linear actuator will be described for simplicity.

1 and 5, two guide rails 21 constituting a linear guide device are fixedly mounted on the upper surface of a rack rail 1 serving as a moving path, and a linear guide is attached to the guide rails 21. A slider body 22 of the apparatus is slidably mounted in the longitudinal direction. The slider body 22 of the linear guide device 20 is attached to the slider 2 of the linear actuator. Between the rack rail 1 and the slider 2, a three-phase variable reluctance type linear motor, which will be described later, and a linear resolver detection device that is a displacement detection unit that detects a relative displacement between the rack rail and the slider are provided. Is equipped.

Two linear guides 21 of the rack rail 1
A rack lamination section 3 formed by laminating electromagnetic steel sheets 25 is provided between them. As shown in FIG. 2A, the electromagnetic steel plate 25 of the rack lamination portion 3 is provided with a large number of teeth 4a and grooves 4b at a predetermined fixed pitch on one side in the longitudinal direction. The bolt insertion holes 26 are formed at predetermined intervals in the longitudinal direction. A large number of the electromagnetic steel sheets 25 are stacked and laminated, and by performing bonding to further improve the strength, the rack lamination part 3 of one block is formed. The rack teeth 4 are formed. As shown in FIG. 2, the rack lamination portion 3 is provided with a rack lamination pressing plate 2 from both sides in the width direction.
7a and 27b, fixing bolts 28 are fixedly penetrated from one rack lamination holding plate 27a to the other rack lamination holding plate 27b through the bolt insertion holes 26 and are integrally formed. The rack lamination portion configured in this manner penetrates a fixing bolt (not shown) penetrated by the both rack lamination holding plates, and is fixed by tightening the fixing bolt to a rack rail between the two guide rails. I have. Thus, on the upper surface of the rack lamination portion 3 of the rack rail, the rack teeth 4 in which the teeth of the respective electromagnetic steel plates are stacked are formed at a fixed pitch in the longitudinal direction of the rack rail 1. The rack rail 1 thus configured is provided with a resin mold 29 for protecting the tooth surfaces of the rack teeth 4.

The slider 2 of the linear actuator
Is a housing 30 having a substantially U-shaped cross section as shown in FIG.
It has. A linear motor magnetic pole portion 5 as a propulsion magnetic pole is provided in the concave portion, facing the rack lamination portion 3 of the rack rail 1. The linear motor magnetic pole part 5 is connected to the rack lamination part 3.
Similarly, as shown in FIG. 4, a large number of electromagnetic steel sheets 34 having four electromagnetic teeth 31 protruding at the same pitch as the fixed pitch of the rack teeth are laminated to form 12 laminated magnetic pole portions 32,
Adjacent laminated magnetic pole portions 32 are arranged opposite to the rack teeth 4 so that a phase difference of 120 ° is generated electrically with respect to the rack lamination portion 3. A thrust generating coil 33 is wound around each of the laminated magnetic pole portions 32, and adjacent laminated magnetic pole portions 32 are sequentially excited with different polarities. In this embodiment, each laminated magnetic pole portion 32
Are generated from one end in the longitudinal direction, A, A,
The three phases were set in the order of B, B, C, C, C, C, B, B, A, A. The illustration of the thrust generating coils of the two stacked magnetic pole portions on the near side in FIG. 4 is omitted.

Each of the laminated magnetic pole portions 32 has a base portion as shown in FIG.
As shown in FIG. 3A, the motor lamination holding plates 35a and 35b are sandwiched from both sides in the longitudinal direction, and each of the laminated portions 32 is inserted through one of the motor lamination holding plates 35a, and the fixing bolt 36 is attached to the other motor lamination holding plate 35b.
And tightening the fixing bolt 36 into the screw hole 37 of the other moor lamination holding plate 35b,
The whole is fixed as an integral magnetic pole block. This magnetic pole block is set in the recess of the housing 30, and the two motor lamination holding plates 35a, 35
b through the fixing bolt 38 and tightened and fixed in the recess,
Further, a resin mold 39 is applied to the outer surface of the magnetic pole block to protect the tooth surface of each magnetic pole.

At one end of the motor lamination section 5, a resolver magnetic pole section 6 of the displacement detecting device of the present invention is mounted. This displacement detection device is a high-resolution inductive displacement transducer for positioning a slider that moves on a rack rail with the thrust of a linear motor with high accuracy. Here, as shown in FIG. 7, two magnetic pole teeth 7a, 7b are respectively provided at the tips of the substantially U-shaped magnetic pole teeth 8a, 8b.
b are stacked, several magnetic pole pair forming steel sheets 40 are laminated, and each magnetic pole tooth 8a,
8b, the exciting coils 9a and 9b are wound in the same direction to form a magnetic pole pair forming piece 41, and a rectangular parallelepiped magnetic body 42 is interposed between the bases of the two magnetic pole pair forming pieces 41. Resolver pole pair 10a (10) having pole teeth 8a, 8b
b, 10c). In this embodiment, the two magnetic pole teeth 8a and 8b opposed to each other with the magnetic body 42 interposed therebetween are paired, so that two magnetic pole teeth 8a and 8b are juxtaposed by the two magnetic pole pair forming pieces 41. become. Since the pair of magnetic pole teeth 8a, 8b are excited to have different polarities by the exciting coils 9a, 9b, the magnetic pole teeth 8a, 8b of the respective magnetic pole pair constituting piece 41 are provided between the two pairs of magnetic pole teeth 8a, 8b. Excitation to different polarities is also performed between 8b.
The reason why the magnetic steel sheets are stacked to form the magnetic pole pair as described above is to prevent generation of eddy current in the magnetic pole pair due to the excited magnetic field.

The three pairs of resolver magnetic poles 10a, 10b, and 10c constructed as described above are used, and as shown in FIG. The three magnetic pole pairs 10a, 10b, and 10c are arranged at a uniform pitch in the tooth trace direction so as to be opposed to the rack teeth 4 in a line, and the respective magnetic pole pairs 10a, 10b, and
The resolver magnetic pole part 6 is formed by shifting the reference numeral 10c in a direction perpendicular to the tooth trace by a pitch of ３ of the fixed pitch P of the rack teeth 4. The exciting coils 9a,
Reference numerals 9, b, and 9c are connected to, for example, a resolver digital conversion circuit as shown in FIG.

In the resolver magnetic pole section 6, the exciting coils 9a, 9c of the respective resolver magnetic pole pairs 10a, 10b, 10c are provided.
When a single-phase sine wave voltage is applied to the b and 9c, as shown in FIG. 9, a pair of opposed magnetic pole teeth 8a and 8b are basically formed.
Of the magnetic pole teeth 8 excited to the N pole by the exciting coil 9a
The magnetic force lines coming out of the line a pass through the rack teeth 4 and return to the magnetic pole teeth 8b excited to the S pole by the exciting coil 9b, thereby closing the magnetic circuit. However, each magnetic pole pair 10
a, 10b, and 10c, the magnetic pole teeth 8a and 8b
As shown in FIG. 10, the magnetic pole teeth 7a and 7b of the magnetic pole teeth 8a and 8b are opposed to each other to form Is different for each magnetic pole pair 10a, 10b, 10c. Therefore, since the magnetic flux densities of the magnetic circuits closed to the respective magnetic pole pairs 10a, 10b, 10c are different, the excitation coils 9a,
The relative inductance of the excitation coils 9a and 9b is different, and the current flowing in the excitation coils 9a and 9b undergoes modulation corresponding to the magnetic field area of the rack teeth 4, and all the excitation coils 9a and 9b
Are respectively 120 ° with respect to this modulation signal current.
It becomes a three-phase current having a phase difference every time.

The three-phase current is amplified by the amplifier 50 in the resolver digital conversion circuit and further converted into two phases by the conversion transformer 51. The sine component and the cosine component are converted into the magnetic field of the rack teeth by the processor 52. The phase according to the area is calculated, and the displacement of each magnetic pole tooth and the slider is calculated from the phase,
The means for calculating the speed and position of the slider from this displacement is described in Japanese Patent Application Laid-Open Nos. Sho 64-43096 and 2-32775, which have been previously proposed by the present applicant, and will not be described in detail here. . In FIG. 3, reference numeral 53 denotes a lead wire of the coil 33 of the linear motor magnetic pole portion 5, and reference numeral 54 denotes a lead wire of the exciting coils 9a and 9b of the linear resolver magnetic pole portion 6.

In this embodiment, as described above, each magnetic pole pair 10a, 10b, 10c has two pairs of magnetic pole teeth 8a, 8a.
b are formed, and the magnetic pole teeth 8a, 8b of the pair of magnetic pole teeth 8a, 8b arranged in the direction orthogonal to the tooth traces of the rack teeth 4 are excited with different polarities. For this reason,
Some of the lines of magnetic force exiting from the magnetic pole tooth 8a excited to the N pole of one pair of magnetic pole teeth pass through the rack teeth 4 and are excited to the S pole of the other pair of magnetic pole teeth. Return to 8b. Therefore, the magnetic pole pairs 10a, 10b, 1
0c means that the entire magnetic field is constituted by the two pairs of magnetic pole teeth 8a and 8b. This is for compensating the fluctuation of the magnetic circuit between each pair of magnetic pole teeth, for example, when the slider is moving at a high speed. By complementing with the pair of magnetic pole teeth, a decrease in the overall magnetic flux density is prevented.

The slider 2 assembled on the upper surface of the rack rail 1 via the linear guide device 20 has the magnetic motor teeth 5 of the linear motor magnetic pole part 5 having the rack teeth 4 of the rack rail 1 as shown in FIG. And a group of magnetic pole teeth 8a and 8b of the linear resolver magnetic pole portion 6 also face the rack teeth 4 with a small gap.

In the linear guide device 20, a slider body 22 having a substantially U-shaped cross section is loosely fitted on a guide rail 21 so as to be relatively movable. As shown in FIG. 6, the guide rail 21 is provided with a single ball rolling groove 57 having a substantially semicircular cross section that is long in the axial direction on both side surfaces thereof. On the other hand, both sleeves 5 of the slider body 22
A ball rolling groove 58 facing the ball rolling groove 57 is formed on the inner surface side of the ball 6, and a load ball rolling path 59 is formed by these two facing grooves. Slider body 22
The ball return passage 6 having a circular cross section and having a circular cross section penetrated in the axial direction in parallel with the
0 is formed.

At the front and rear ends of the slider body 22, end caps 61 having a substantially U-shaped cross section, which are injection molded products of a synthetic resin material, are joined by screws 62, respectively. This end cap has a semi-doughnut-shaped curved path 6 formed by fitting a semi-cylindrical return guide 64 into a semi-circular recess.
The ball circulation path is formed by connecting the load ball rolling path 59 and the ball return path 60 to each other. A large number of steel balls 66 are rollably loaded in the ball circulation path. The inner end of the curved path 65 of the end cap 61 is formed with a ball-scooping protrusion 67 projecting inward in a semicircular shape, and the acute-angled tip is formed by a ball rolling groove of the guide rail 21. 57 is loosely fitted.

[0025]

As described above, according to the displacement detecting device of the present invention, a pair of magnetic pole teeth which are excited to have different polarities are arranged in the tooth trace direction of the fixed tooth and face the fixed tooth. Since the magnetic circuit formed in the fixed tooth from the magnetic pole pair passes through only one fixed tooth without straddling at least the adjacent fixed tooth, the magnetic circuit formed adjacent to the fixed tooth has a seam. Even if the interlocking teeth are split,
The displacement of the moving body can be detected continuously. Also,
The installation space can be reduced as much as there is no need to install the resolver detection teeth separately from the fixed teeth as in the related art. Further, since two or more pairs of magnetic poles are arranged in the direction perpendicular to the tooth trace of the fixed tooth while being arranged in the direction of the tooth trace of the fixed tooth, the degree of protrusion of the resolver magnetic pole body support from the moving body is reduced. The moving distance of the moving body is not hindered. Further, the magnetic pole pair is perpendicular to the tooth trace of the fixed tooth.
When side by side, adjacent magnetic pole teeth of adjacent magnetic pole pairs are different
Excitation to polarity, and magnetically joined between each magnetic pole,
The line of magnetic force deviated in the orthogonal direction from the tooth trace of the fixed tooth
Can be supplemented with magnetic pole teeth, preventing a decrease in overall magnetic flux density
When the moving body is moving at high speed,
The fluctuation of the magnetic circuit between the two can be compensated.

[Brief description of the drawings]

FIG. 1 is an overall top view of a linear actuator using a displacement detection device according to the present invention.

FIGS. 2A and 2B are explanatory views of a rack rail constituting a moving path of the linear actuator of FIG. 1, wherein FIG. 2A is a side view of an electromagnetic steel plate constituting a rack lamination portion of the rack rail, and FIG. It is the whole longitudinal section of a rack rail in an HH section.

3A and 3B are explanatory views of a slider constituting a moving body of the linear actuator of FIG. 1, wherein FIG. 3A is an overall bottom view of the slider, and FIG. 3B is an overall longitudinal sectional view of the slider.

FIG. 4 is a perspective view of a motor lamination unit mounted on the slider of FIG. 3;

FIG. 5 is a sectional view of the linear actuator of FIG. 1 taken along line GG.

FIG. 6 is a detailed explanatory view of a linear guide device used in the linear actuator of FIG. 1;

FIG. 7 is an assembly explanatory diagram of each resolver magnetic pole pair used in the linear resolver magnetic pole part of the linear actuator of FIG. 1;

FIG. 8 is an overall assembly explanatory view of a linear resolver magnetic pole part of the linear actuator of FIG. 1;

9A and 9B are explanatory diagrams of a magnetic circuit formed in the linear resolver magnetic pole part of FIG. 8; FIG.
(B) is a view on arrow Y in FIG. 8.

10A and 10B are explanatory diagrams of a magnetic circuit formed in the linear resolver magnetic pole part of FIG. 8; FIG. 10A is a cross-sectional view of FIG. 8B, FIG. 10B is a cross-sectional view of FIG. It is F sectional drawing of 8.

11A and 11B are explanatory diagrams of a magnetic circuit formed in the linear resolver magnetic pole part of FIG. 8; FIG. 11A is a cross-sectional view of FIG. 8A, FIG. 11B is a cross-sectional view of FIG. It is E sectional drawing of 8.

FIG. 12 is a block diagram of a linear resolver conversion circuit used in the displacement detection device of the linear actuator in FIG. 1;

FIG. 13 is a top view showing an example of a displacement detection device using a conventional linear resolver conversion circuit.

FIG. 14 is a top view showing another example of a displacement detection device using a conventional linear resolver conversion circuit.

FIG. 15 is a side view showing a conventional magnetic pole pair used in a linear resolver conversion circuit.

16 is an explanatory diagram of a case where a magnetic circuit is not formed in the magnetic pole pair of FIG.

[Explanation of symbols]

 1 is a rack rail 2 is a slider 3 is a rack lamination part 4 is a rack tooth 5 is a motor lamination part 6 is a resolver magnetic pole part 7a, 7b is a magnetic pole tooth 8a, 8b is a magnetic pole tooth 9a, 9b is an exciting coil 10a to 10c is a magnetic pole versus

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B ⁷ /00-7/34 G01D 5/245

Claims (2)

(57) [Claims] 1. A displacement detecting device for a moving body which moves along a moving path made of a magnetic material having fixed teeth formed at predetermined fixed pitches, wherein a pair of magnetic pole teeth excited to different polarities are fixed teeth. A magnetic pole pair is formed so as to face the fixed tooth side by side in the tooth trace direction, and two or more different pairs of magnetic poles are arranged in a direction perpendicular to the tooth trace while being arranged in the tooth trace direction of the fixed tooth. A displacement detection device characterized by the above-mentioned. 2. The method according to claim 1, wherein the magnetic pole pair is orthogonal to the tooth trace of the fixed tooth.
The magnetic pole teeth of adjacent magnetic pole pairs are
Excitation to different polarities, each magnetic pole is magnetically joined
The displacement detecting device according to claim 1, wherein
Place.