JP2001174247A - Displacement detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a displacement detecting apparatus, capable of measuring at high accuracy by eliminating the influence of heat due to a heating body, even if the heating body forms either a fixed part to be mounted or a movable table. SOLUTION: A linear encoder 10 for detecting the displacement of the movable table 2 which is reciprocaltively movable relative to the fixed part 1 on a straight line, comprises a main body 11 mounted on the fixed part 1 and a detector 12 mounted on the movable table 2 and the body 11 comprises a heat-absorbing means 9 for forcibly absorbing heat transferred from the fixed part 1. Heat of the fixed part 1 is made to escape to the putside through the heat-absorbing means 9, if the fixed pat 1 is heated up, and hence the heat will not conduct to the interior of the body 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement detecting device which is attached to a driving device in which a movable table reciprocates with respect to a fixed portion, and detects a linear displacement of the movable table.

[0002]

2. Description of the Related Art Conventionally, a driving device for reciprocating a movable table with respect to a fixed portion is incorporated in a machine tool, a transfer device, or the like. In some of the driving devices, the movable table is controlled in positioning with high accuracy. In this case, a displacement detecting device is used to detect a linear displacement of the movable table with respect to a fixed portion of the driving device.

FIG. 7 is a schematic view of a conventional example showing a state in which a displacement detecting device is attached to a driving device. In FIG. 7, the movable table 100 has a basic structure in which a nut 102 is fixed to a lower surface of a machine table 101 on which articles and works are placed, and the nut 102 is screwed to a ball screw 103. The ball screw 103 has both ends rotatably attached to a fixed portion (not shown).
One end thereof is connected to a rotary motor 104 composed of a servomotor. As the rotary motor 104 rotates in the forward and reverse directions, the movable table 100 reciprocates along the axial direction of the ball screw 103.

Since the positioning of the movable table 100 needs to be controlled with high precision, the rotary motor 104 has a rotary encoder 105 for detecting the speed of the movable table 100.
The movable table 100 and the fixed portion are provided with a displacement detection device 106 that detects the amount of linear movement of the movable table 100. This displacement detection device 106
Is composed of a linear encoder having a main body 107 attached to the fixed part and a detector 108 attached to the movable table 100. The detection signal sent from the detector 108 is a position / speed control device (controller) 10
9, the control signal of the position command is sent to the servo amplifier 110
Through the rotary motor 104.

[0005]

Generally, since a motor such as the rotary motor 104 is a heat source, when this heat is transmitted to the displacement detecting device or the movable table 100, the accuracy of the positioning control of the movable table 100 is reduced. I do. In the above-described conventional example, the rotary motor 104 is fixed at one location, and the location thereof is
And the displacement detection device 106, it is easy to take measures to prevent heat generated by the rotary motor 104 from affecting the movable table 100 and the displacement detection device 106.

Recently, in order to move the movable table 100 at high speed or at high acceleration / deceleration, a linear motor is being used in a driving device instead of a rotary motor. To move the movable table 100 using this linear motor, an exciting coil is attached to one of the movable table and the fixed part, and a magnet is attached to the other of the movable table and the fixed part. These coils and magnets are attached to a movable table and a fixed portion in a relatively wide range.

Generally, a moving coil type linear motor in which an exciting coil is integrated with a movable table is often used. When this type of linear motor is incorporated in a driving device, the movable table has an exciting source serving as a heat source. Since the coils are arranged in a wide range, the movable table itself becomes a heating element. The heat generated by the motor rises to about 100 ° C., although it varies depending on the load. This heat is directly transmitted to the displacement detection device constituted by the linear encoder, which causes the accuracy of the displacement detection device, deterioration of electronic components, and failure.

[0008] An object of the present invention is to eliminate the influence of heat generated by this heating element even when one of the fixed portion and the movable table to be attached constitutes a heating element, to suppress deterioration of electronic components, and to achieve high precision. Another object of the present invention is to provide a displacement detection device capable of performing measurement at a time.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to achieve the above object by forcibly absorbing heat generated by a heating element. Specifically, in the displacement detection device of the present invention, one of the fixed portion and the movable table that reciprocates with respect to the fixed portion is attached to a driving device that forms a heating element, and the linear displacement of the movable table is A main body attached to one of the fixed part and the movable table, and a detector attached to the other of the fixed part and the movable table, and a main body attached to the heating element Alternatively, the detector is provided with heat absorbing means for forcibly absorbing heat transmitted from the heating element.

In the present invention having this structure, even if the fixed portion or the movable table constituting the heating element generates heat, the main body or the detector attached to the heating element has the heat absorbing means. Through the heat, the heat of the heating element is released to the outside. Therefore, since the main body or the detector is cooled and the heat is hardly transmitted to the inside, it is possible to perform high-precision measurement without adversely affecting the electronic components and the like provided inside the main body and the detector. it can.

Here, in the present invention, the heat absorbing means comprises:
A configuration may be provided that includes a flow path formed in the main body or the detector attached to the heating element, and a fluid supply unit that sends a cooled fluid into the flow path. In this configuration, by flowing a cooled fluid, for example, cooling water, cooling air, liquid nitrogen, or the like, in the flow path, the cooled fluid deprives the heat from the heating element, and is efficiently. Can be cooled.

Further, it is preferable that the flow path is formed inside the main body or the detector. In this configuration,
Not only can the size of the main body and the detector be the same as before, but also cooling of the vicinity of the part where the electronic components are arranged can reliably prevent the transfer of heat to the electronic components .

Further, in the present invention, the heat absorbing means may be a Peltier device. In this configuration, it is not necessary to adopt a structure for preventing the leakage of the cooling fluid into the main body or the inside of the detector, so that the structure can be simplified. In the above, in the present invention, the driving device is a linear motor, and the heating element is provided with an exciting coil.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a displacement detecting device according to the present invention will be described below in detail with reference to the accompanying drawings. In the following description, the same components will be denoted by the same reference numerals, and the description thereof will be omitted or simplified. [First Embodiment] A first embodiment is shown in FIGS. FIG. 1 is a schematic configuration diagram showing a state where the displacement detection device of the present embodiment is incorporated in a drive device.

In FIG. 1, a driving device is incorporated in a device such as a machine tool or a transport device, and includes a fixed portion 1 and a movable table 2 reciprocating with respect to the fixed portion 1. The movable table 2 is for placing articles and works (not shown). An excitation coil group 3 is provided on the fixed portion 1 along the reciprocating direction of the movable table 2, and a magnet 4 is provided on a portion of the movable table 2 facing the excitation coil group 3. A linear motor 5 is configured by the exciting coil group 3 and the magnet 4. When the exciting coil group 3 is energized, the movable table 2 provided with the magnet 4 reciprocates. In the first embodiment, since the excitation coil group 3 generates heat when energized, the fixing unit 1 forms a heating element.

A linear encoder main body 11 is mounted on the fixed portion 1, and a detector 12 is mounted on the movable table 2. A linear encoder 10 is configured as a displacement detection device that detects a linear displacement of the movable table 2 from the main body 11 and the detector 12. The detection signal sent from the detector 12 is sent to the position / speed control device 6, and the position / speed control device 6 converts the control signal generated based on the detection signal into the excitation coil group via the servo amplifier 7. 3 to control the position of the movable table 2.

FIGS. 2 and 3 show a detailed configuration of the linear encoder 10. FIG. FIG. 2 is a front view of the linear encoder 10, and FIG. 3 is a perspective view in which a part of the linear encoder 10 is cut away. Note that in FIG.
2 and FIG. 3, the detector 12 is disposed under the main body 11. In FIGS. 2 and 3, a main body 11 is formed of aluminum and has a substantially box-shaped casing 13 whose longitudinal direction coincides with the direction in which the exciting coil group 3 is arranged, and a main body provided inside the casing 13. It comprises a scale 14 and electronic components (not shown), and a plurality of mounting portions 11A fixed to the upper portion of the casing 13 for mounting the main body 11 on the front of the fixing portion 1.

The casing 13 has lids 11B attached to both open end surfaces thereof, and a flow passage 13A is formed in the interior close to the fixed portion 1 side so as to extend in the longitudinal direction of the main body 11. This flow path 13A is a single flow path having an L-shaped cross section with a wide upper part and a narrow lower part.

One end of the flow path 13A has a fluid supply pipe 1
5A, and the other end is connected to the fluid discharge pipe 15B. The fluid supply pipe 15A is provided with a pump 17 for supplying the cooling fluid stored in the tank 16A to the flow path 13A. The downstream end of the fluid discharge pipe 15B is open to the tank 16B. The fluid supply pipe 15A and the fluid discharge pipe 15B have their ends penetrating and attached to the lid 11B. These tanks 16A, 1
The cooling fluid may be circulated for use with one 6B. In this case, it is preferable that a cooling device is installed in the tank and the fluid supplied from the pump 17 is always cooled.

In the first embodiment, a fluid supply means 8 for sending a cooling fluid from the fluid supply pipe 15A, the pump 17 and the tank 16A to the inside of the flow path 13A is provided. further,
A heat absorbing means 9 forcibly absorbing heat transmitted from the heating element from the fluid supply means 8, the flow path 13A, the fluid discharge pipe 15B, and the tank 16B is configured. The cooling fluid used in the first embodiment is water, air, oil, liquid nitrogen, or the like, and the temperature may be lower than the heat generation temperature of the fixed unit 1.
For example, the temperature may be room temperature (about 20 ° C.), 0 ° C. or lower below room temperature, or 0 ° C. or lower. Considering the cooling effect, the lower the cooling temperature, the better,
Since there is a disadvantage such as dew condensation on electronic components, etc.
Preferred is a temperature range of from 20 ° C to 20 ° C. When cooling air is used as a cooling fluid, it is not always necessary to provide the fluid discharge pipe 15B and the tank 16B.

In the first embodiment, the flow path 13A is not limited to the cross-sectional shape shown in FIG.
Any specific cross-sectional shape can be used as long as it cools the inside of the device. For example, as shown in FIG.
May be formed from a plurality of flow holes 13B. Channel 13
If A is formed from a plurality of flow holes 13B, the cooling capacity can be adjusted by selecting the number of flow holes 13B through which the cooling fluid flows. In addition, in FIG.
B has a circular cross section, but the specific shape of the cross section is not limited. For example, a triangular cross section, a semicircular cross section,
The shape may be a rectangular shape or the like.

In FIG. 2, the detector 12 includes a casing 12A attached to the movable table 2, an index scale 27 (see FIG. 4) and electronic components (not shown) provided inside the casing 12A. It is composed of The index scale 27 of the detector 12 is formed in a U-shaped cross section so as to sandwich the main scale 14 of the main body 11, and the relative positions of these scales are sent to a position / speed control device (not shown) through the cable 18.

Therefore, (1) In the first embodiment, the fixing portion 1
Is attached to a driving device constituting a heating element, and
A linear encoder 10 for detecting a linear displacement of a movable table 2 reciprocating with respect to a main body 11 attached to a fixed portion 1 and a detector 12 attached to the movable table 2 and serving as a heating element. Since the main body 11 attached to the fixed part 1 is provided with the heat absorbing means 9 for forcibly absorbing the heat transmitted from the fixed part 1,
Even if the fixing part 1 generates heat, the fixing part 1
Heat is released to the outside. Therefore, this heat is
Because it is less transmitted to the inside of the main body 11 and the detector 1
The measurement can be performed with high accuracy without adversely affecting the electronic components and the like provided in the interior of the device 2.

Further, (2) the heat absorbing means 9 is provided with a flow path 13A formed in the main body 11 and a fluid supply means 8 for sending a cooled fluid to the inside of the flow path 13A. As a result, the cooling fluid surely deprives the heat transmitted from the fixed portion 1, and the cooling can be performed efficiently.
(3) Since the flow path 13A is formed inside the main body 11, not only can the size of the main body 11 be the same as that of a normal linear scale, but also the portion where the electronic components are arranged can be formed. By cooling the vicinity, transmission of heat to the electronic component can be reliably prevented. (4) Since the heat absorbing means 9 is provided on the main body 11 attached to the fixing part 1, even if the detector 12 moves during measurement, the fluid supply pipe 15A and the fluid discharge pipe 15 constituting the heat absorbing means 9 are provided.
B does not move. Therefore, since the movement of the detector 12 is not hindered, no measurement error occurs.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that the movable table 2 constitutes a heating element and is a detector for forming a flow path, and other configurations are the same as those of the first embodiment. . The linear encoder 20 of the second embodiment is used for controlling the positioning of the movable table 2 as in the linear encoder 10 shown in FIG.

FIG. 5 shows a detailed configuration of the linear encoder 20 according to the second embodiment. FIG. 5 corresponds to FIG. 3 and is a perspective view in which a part of the linear encoder 20 is cut away. In FIG. 5, the linear encoder 2
Reference numeral 0 denotes a main body 21 attached to the fixed unit 1 and a detector 22 attached to the movable table 2. In the second embodiment, the exciting coil group 3 and the magnet 4 are mounted in the opposite manner to the first embodiment. That is, the movable table 2 is provided with the exciting coil group 3, and the magnet 4 is provided in a portion of the fixed portion 1 facing the exciting coil group 3. The movable table 2 constitutes a heating element.

The main body 21 has a substantially box-shaped casing 23 whose longitudinal direction coincides with the direction in which the exciting coil groups 3 are arranged.
And a conventional structure including a main scale 14 and electronic components (not shown) provided inside the casing 23, respectively. The detector 22 includes a casing 22A attached to the movable table 2 and a casing 22A.
Index scale 27 provided inside each
And electronic components (not shown).

Index scale 27 of detector 22
Are formed in a U-shaped section so as to sandwich the main scale 14 of the main body 21, and the relative positions of these scales are sent to a position / speed control device (not shown) through a cable 18. A flow path 22B is formed through the casing 22A in the vicinity of the movable table 2 side. The flow path 22B is a single flow path having a rectangular cross section, one end of which is connected to the fluid supply pipe 15A, and the other end of which is connected to the fluid discharge pipe 15B. In the second embodiment, the fluid supply means 8, the flow path 22B, the fluid discharge pipe 15
A heat absorbing means 29 for forcibly absorbing heat transmitted from the heating element from B and the tank 16B is provided.

Therefore, (5) In the second embodiment, the movable table 2 is attached to a drive device constituting a heating element, and detects a linear displacement of the movable table 2 reciprocating with respect to the fixed portion 1. 20, comprising a main body 21 attached to the fixed portion 1 and a detector 22 attached to the movable table 2, and the detector 22 attached to the movable table 2 which is a heating element is transmitted from the movable table 2. Since the heat absorbing means 29 for forcibly absorbing heat is provided, even if the movable table 2 generates heat,
The heat of the movable table 2 is released outside through the heat absorbing means 29. Therefore, since this heat is hardly transmitted to the inside of the detector 22, it is possible to perform high-precision measurement without adversely affecting the electronic components and the like provided inside the main body 11 and the detector 12.

(6) The heat absorbing means 29 is provided with the detector 2
2 and the fluid supply means 8 for sending a cooled fluid to the inside of the flow channel 22B, so that the cooling fluid can reliably transfer the heat transmitted from the movable table 2. And cooling can be performed efficiently. (7) Since the flow path 22B is formed inside the detector 22, not only can the size of the detector 22 be the same as that of a normal linear scale, but also electronic components are arranged. By cooling the vicinity of the portion, transmission of heat to the electronic component can be reliably prevented.

[Third Embodiment] Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment differs from the first embodiment in the basic configuration and the main body of the heat absorbing means, and the other configurations are the same as those in the first embodiment. The linear encoder 30 of the third embodiment is used for controlling the positioning of the movable table 2 as in the linear encoder 10 shown in FIG.

FIG. 6 shows a detailed configuration of the linear encoder 30 according to the third embodiment. FIG. 6 corresponds to FIG. 3 and is a perspective view in which a part of the linear encoder 30 is cut away. In FIG. 6, the linear encoder 3
Reference numeral 0 denotes a main body 31 attached to the fixed unit 1 and the detector 12 attached to the movable table 2. The main body 31 is formed of aluminum and is a group of exciting coils 3.
The casing 33 is provided with a substantially box-shaped casing 33 whose longitudinal direction coincides with the arrangement direction, the main scale 14 provided inside the casing 33, and electronic components (not shown).

A Peltier element 39 is provided on the surface and the upper surface of the casing 33 facing the fixing portion 1, respectively.
Are provided in a strip shape in the longitudinal direction. The Peltier element 39 provided on the surface facing the fixing portion 1 is composed of a plurality of Peltier elements which are fitted into a plurality of fitting grooves 33A formed in the casing 33, respectively. The Peltier element 39 provided on the upper surface is constituted by one protrudingly formed from the upper surface. These Peltier elements 39 constitute heat absorbing means for cooling the casing 33 by controlling the amount of electricity by control means (not shown).

Therefore, in the third embodiment, in addition to the same operation and effect as (1) of the first embodiment, the following operation and effect can be obtained. That is, (8) In the third embodiment,
Since the heat absorbing means 39 is formed of a Peltier element, it is not necessary to employ a structure for preventing the cooling fluid from leaking into the main body 11 or the detector 22 as in the first and second embodiments. Therefore, the structure can be simplified. Further, by controlling the amount of current supplied to the Peltier element 39, the cooling temperature can be easily controlled. (9) Since the Peltier element 39 is provided at a position facing the fixed portion 1 of the casing 33 of the main body 31, the hottest part is concentrated and cooled by the Peltier element 39, thereby increasing the cooling efficiency. Things.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and various improvements and design changes may be made without departing from the scope of the present invention. Is possible. In each of the above embodiments, the linear encoders 10, 20, and 30 optically detect the relative position of the movable table. However, the linear encoders 10, 20, and 30 may detect the relative position of the movable table by magnetic force.

Further, in each of the above-described embodiments, the case where the fixed portion 1 and the movable table 2 generate heat by the exciting coil is applied. However, the present invention is not limited to this case, and the fixed portion 1 and the movable table 2 are not limited to this case. The same applies to the case where the movable table 2 generates heat. Further, a structure may be employed in which the main bodies 11, 21, 31 are attached to the movable table 2, and the detectors 12, 22 are attached to the fixed portion 1. Further, the heat absorbing means may be constituted by a heat pipe or the like.

[0037]

As described above, according to the present invention, even when one of the fixed portion to be mounted and the movable table forms a heating element, the heat generated by the heating element is forcibly absorbed. Therefore, there is an effect that measurement can be performed with high accuracy by eliminating the influence of heat due to the heating element.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a state where a displacement detection device (linear encoder) according to a first embodiment of the present invention is incorporated in a drive device.

FIG. 2 is a front view of the linear encoder according to the first embodiment.

FIG. 3 is a perspective view in which a part of the linear encoder according to the first embodiment is broken.

FIG. 4 is a partially broken perspective view showing a different flow path shape of the first embodiment.

FIG. 5 is a perspective view in which a part of a linear encoder according to a second embodiment is broken.

FIG. 6 is a perspective view in which a part of a linear encoder according to a third embodiment is broken.

FIG. 7 is a schematic diagram showing a state in which a conventional displacement detection device is attached to a driving device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed part 2 Movable table 3 Excitation coil group 4 Magnet 5 Linear motor 8 Fluid supply means 9,29 Heat absorption means 10,20,30 Linear encoder 11,21 Main body 12,22 Detector 13,33 Casing 13A, 23B Flow Road 39 Peltier element (heat absorbing means)

Claims (5)

[Claims] 1. A displacement detecting device for detecting a linear displacement of a movable table, wherein one of a fixed section and a movable table reciprocating with respect to the fixed section is attached to a driving device constituting a heating element. And a detector attached to one of the fixed part and the movable table, and a detector attached to the other of the fixed part and the movable table, wherein the main body or the detector attached to the heating element is the heating element. A displacement detecting device comprising a heat absorbing means for forcibly absorbing heat transmitted from the device. 2. The displacement detecting device according to claim 1, wherein the heat absorbing means includes a flow path formed in a main body or a detector attached to the heating element, and a fluid cooled inside the flow path. And a fluid supply means for sending the displacement. 3. The displacement detecting device according to claim 2, wherein the flow path is formed inside the main body or the detector. 4. The displacement detecting device according to claim 1, wherein said heat absorbing means is a Peltier element. 5. The displacement detection device according to claim 1, wherein the drive device is a linear motor, and an excitation coil is attached to the heating element. apparatus.