JP3001320U - Electric motor with reduction gear - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a motor with a reducer capable of detecting a rotation angle of an arbitrary range of an output shaft regardless of the configuration of a rotational displacement sensor attached to the output shaft. [Structure] A reduction mechanism 12 for driving a load is housed in a case 11, and a rotary shaft of an electric motor 15 attached to the case 11 is coupled to an input portion of the reduction mechanism 12. The output shaft 13 whose one end 13a is connected to the load is supported by the case 11,
Is coupled to the gear 12h at the output end of the reduction mechanism 12. The other end of the output shaft 13 is coupled to the input portion of the sensor driving speed reducer 17, and the output portion of the sensor driving speed reducer 17 is coupled to the coupling 2
It is connected to the input shaft 16A of the rotational displacement sensor 16 via 0.

Description

[Detailed description of the device]

The present invention relates to an electric motor with a speed reducer equipped with a rotational displacement sensor that detects rotational displacement of an output shaft.

[0002]

[Prior art]

 An electric motor with a speed reducer equipped with a rotational displacement sensor is used, for example, in various control devices to operate an operation unit. For example, in a control device for an internal combustion engine, an electric motor with a reducer equipped with a rotational displacement sensor as an actuator for operating a means (throttle valve or control rack of a fuel pump) for adjusting the amount of fuel supplied to the internal combustion engine. Is used.

In addition, in a load driven by an electric motor through a speed reducer, when it is necessary to control the position of the load so as to match the target position, a speed reducer is attached to detect the position of the load. A rotational displacement sensor may be attached to the output shaft of the electric motor.

FIG. 3 shows a conventional electric motor with reduction gear (actually developed flat 3-39367) having a rotational displacement sensor attached to an output shaft. In FIG. 3, 1 is a first case half portion 1A and A case divided into two parts in the second case half portion 1B, 2 is a gear reduction mechanism for driving a load housed in the case 1, 3 is supported by the case 1 and coupled to an output part of the gear reduction mechanism 3. The case 1, the gear reduction mechanism 2, and the output shaft 3 constitute a reduction gear 4 for driving a load. Reference numeral 5 is an electric motor attached to the second case half portion 1B, and its rotating shaft 5a is introduced into the case 1.

The gear reduction mechanism 2 reduces the rotation of the electric motor by means of gears 2a to 2f and transmits it to the output shaft 3. The gear 2a constituting the input part of the reduction mechanism is attached to the rotation shaft 5a of the electric motor. Has been. The output shaft 3 is rotatably supported by the second case half portion 1B via a bearing, and the output shaft 3 is attached with a gear 2f that constitutes an output portion of the reduction gear mechanism 2. One end 3a connected to the load of the output shaft 3 is led out from the second case half portion 1B.

A sensor housing portion 1A1 is integrally provided at an end portion of the first case half portion 1A located on the extension line of the other end of the output shaft 3 of the load driving speed reducer, and inside the sensor housing portion 1A1. The rotary displacement sensor 6 is housed in. The rotational displacement sensor 6 has an input shaft 6A and a signal generation unit 6B that generates a detection signal including rotation angle information of the input shaft. The input shaft 6A is the output shaft 3 of the load drive speed reducer. It is directly connected to the end. One end of the output lead wire 7 is soldered to the output terminal of the signal generator 6B. The other end of the lead wire 7 is led out to the outside through a grommet (not shown) attached to the first case half portion 1A.

The rotary displacement sensor 6 outputs a detection signal including information on the rotation angle of the input shaft 6A, and is composed of, for example, a potentiometer, a differential transformer, a rotary encoder and the like.

In the above-described electric motor with reduction gear, the rotation of the electric motor 5 is transmitted to the output shaft 3 via the reduction gear mechanism 2, and the rotation of the output shaft 3 drives a load (not shown). The rotation of the output shaft 3 is transmitted to the input shaft of the rotational displacement sensor 6 on a one-to-one basis, and the signal generator 6B outputs a detection signal (a detection signal including information about the rotation angle) corresponding to the rotation angle of the output shaft 3. To do.

[0009]

[Problems to be solved by the device]

 In the conventional electric motor with reduction gear, the input shaft 6A of the rotational displacement sensor 6 and the output shaft 3 of the reduction gear are directly connected, and the rotation of the output shaft 3 and the rotation of the input shaft 6A are in a one-to-one correspondence. Therefore, the range of the rotation angle of the output shaft 3 that can be detected is equal to the range of the rotation angle that the rotational displacement sensor 6 can detect.

As the rotational displacement sensor 6, for example, an endless type sensor capable of detecting an angle (360 degrees) of one rotation of the input shaft may be used. In this case, one rotation of the output shaft 3 is used. Only the angle can be detected.

However, in order to detect the position of the load from the rotation angle of the output shaft of the electric motor with reduction gear, it is often necessary to detect the rotation angle of the output shaft 3 over a plurality of rotations. is there. For example, a combine has a grain discharge pipe called an auger cylinder for discharging threshed grains, and the grain discharge pipe is driven by an electric motor with a speed reducer to rotate. In this case, if the turning position of the grain discharge pipe is detected from the rotation angle of the output shaft of the reducer-equipped motor and control is performed to stop the grain discharge pipe at the target position, the output shaft of the motor with reducer It is necessary to detect the rotation angle over multiple turns.

In order to be able to detect the rotation angle of the output shaft of the motor with a reduction gear over a plurality of rotations, a multi-rotation type that has a built-in reduction mechanism and can detect a rotation angle over a plurality of rotations It is conceivable to use the above rotational displacement sensor. For example, if it is necessary to detect the rotational angle displacement of the output shaft over 10 rotations, use a 10-rotation multi-rotation type rotation sensor with a rated detection angle of 3600 (= 360 × 10) degrees. Good.

However, the commercially available multi-rotation rotary displacement sensor has a fixed detection angle (detectable rotation angle) such as a 5-rotation type or a 10-rotation type, and therefore detects a rotation angle in the middle. There is also a problem that it cannot be applied when it is necessary to detect a rotation angle exceeding the rated detection angle.

In addition, at the manufacturing stage of the actuator, with the rotational displacement sensor attached to the output shaft 3, it is possible to inspect whether or not the electric displacement of the electric motor 5 and the speed reduction mechanism 2 and the rotational displacement sensor 6 is good, and to detect the rotational angle. However, it is necessary to perform these inspections and measurements while rotating the sensor. Therefore, in this type of electric motor, it is preferable that the output shaft can be continuously rotated when measuring the characteristics.

However, in general, a multi-rotational rotational displacement sensor is provided with a stopper that prevents the rotation of the input shaft when the rotation angle of the input shaft reaches the rated detection angle, and the rotation angle of the input shaft is the rated value. When the detection angle is reached, the rotation stops.Therefore, when a multi-rotational rotary displacement sensor is attached to the output shaft of a motor with a reducer, there is a problem that the motor cannot be rotated continuously. It was

One object of the present invention is to make it possible to appropriately set an actually detectable angle range without being limited by the rated detection angle of the rotational displacement sensor attached to the output shaft. It is to provide an electric motor with a reduction gear.

Another object of the present invention is to use an endless type sensor capable of continuous rotation as a rotational displacement sensor attached to an output shaft, and to detect a rotation angle over many rotations. To provide an electric motor with a speed reducer.

[0018]

[Means for Solving the Problems]

 The present invention comprises a load driving speed reducer in which a load driving speed reducing mechanism is housed in a case, and an electric motor attached to the case and having a rotating shaft coupled to an input portion of the load driving speed reducing mechanism. Thus, the present invention relates to a motor with a reduction gear in which one end of the output shaft of the load driving reduction gear is connected to a load.

According to the present invention, the rotation driving device includes a sensor driving speed reducer having an input unit coupled to the other end of the output shaft, and a rotational displacement sensor having an input shaft coupled to the output unit of the sensor driving speed reducer. A displacement detector is provided and the rotational displacement detector is attached to the case.

The rotary displacement sensor outputs a detection signal corresponding to the rotation angle of the input shaft. As a sensor of this type, a change in resistance value is used like a potentiometer or a differential transformer. There are analog type sensors such as those that utilize the change in inductance as described above and digital type sensors such as rotary encoders that generate a pulse for each minute rotation angle.The rotary displacement sensor used in the present invention is Any of these forms may be used. Which type of rotational displacement sensor is used is determined according to the application of the actuator and the configuration of the control device for inputting the output signal thereof. The detection signal output by the rotation displacement sensor may be an electric signal (voltage, current, resistance value, reactance value, etc.) or an optical signal.

As described above, when the output shaft of the load drive speed reducer is connected to the input shaft of the rotational displacement sensor via the sensor drive speed reducer, the speed reduction ratio of the sensor drive speed reducer can be appropriately selected. As a result, the predetermined rotation angle can be detected without being influenced by the rated detection angle of the rotational displacement sensor.

For example, if an endless type capable of detecting an angle of 360 degrees is used as the rotational displacement sensor and the reduction ratio of the sensor driving reduction gear is set to 10: 1, the rotational angle of 10 rotations ( = 3600 degrees) can be detected with the same resolution as a rotational displacement sensor that detects an angle of 360 degrees. Also, for example, if a 5-rotation multi-rotation rotary displacement sensor is used and the reduction ratio of the sensor drive reduction gear is set to 1.4 to 1, it is possible to detect the rotation angle over 7 rotations. Become.

In the above configuration, the output shaft of the load drive speed reducer is connected to the input part of the sensor drive speed reducer, but the load drive speed reduction mechanism is a gear speed reduction mechanism using gears. In this case, the input portion of the sensor drive speed reducer may be connected to the shaft of the gear that is positioned upstream of the gear that is connected to the output shaft among the gears that form the gear reduction mechanism.

An electric motor with a speed reducer according to the present invention includes, for example, a case formed by dividing the first case half part and the second case half part into two parts, and the first and second case half parts. The output shaft, which is arranged so as to face the opposite direction of the housing, is supported by the case via a bearing and is connected to the load, and one end of which is led out to the outside from the second case half side and is housed in the case. A reduction mechanism for driving a load, which is housed and has an output unit coupled to an output shaft; and an electric motor, which is attached to the first case half and whose rotating shaft is coupled to an input unit of the reduction mechanism for driving a load, 1 and a rotational displacement detector attached to the case half.

In the above configuration, the electric motor is attached to the first case half, but the electric motor may be attached to the second case half.

When the rotational displacement detector is connected to the other end of the output shaft, the rotational displacement detector needs to be attached to the first case half side, but the teeth constituting the load drive reduction mechanism are required. When the rotational displacement detector is connected to the shaft of the gear located on the upstream side of the gear to which the output shaft is connected in the vehicle, the rotational displacement detector is connected to the first cover half and the second cover half. It may be mounted on either side of the cover half.

In each of the above-described configurations, it is preferable to use an endless type sensor as the rotational displacement sensor, which has no limitation on the rotational angle range of the input shaft and can detect a rotational angle of 360 degrees.

The endless type rotational displacement sensor is configured so that its input shaft can rotate indefinitely (continuous rotation), and outputs a detection signal corresponding to the rotation angle over a rotation angle range of 360 degrees. It is a sensor that outputs.

When the endless type rotary displacement sensor is used, the electric motor can be continuously rotated, and therefore it is easy to measure the characteristics of the rotary displacement sensor and the quality of matching between the reduction gear and the rotary displacement sensor. Can be done. Moreover, in this case, it is possible to detect the rotation angle over many rotations by appropriately setting the reduction ratio of the sensor drive reduction gear.

A gear speed reducer may be used as the sensor driving speed reducer. In this case, it is desirable to cut the input gear directly to the other end of the output shaft to simplify the structure of the speed reducer.

[0031]

[Action]

 As described above, the sensor of the output shaft of the load drive speed reducer or of the gears forming the load drive speed reduction mechanism, which is located on the upstream side of the gear connected to the output shaft When coupled to the input shaft of the rotational displacement sensor via the drive reduction gear, it can be detected without being limited by the rated detection angle of the rotary displacement sensor by selecting the reduction ratio of the sensor drive reduction mechanism appropriately. The range of various rotation angles can be set to any size.

In particular, when an endless type rotational displacement sensor capable of continuous rotation is used as the rotational displacement sensor, it is possible to continuously rotate the electric motor and to detect a rotation angle over many rotations. You can

[0033]

【Example】

 FIG. 1 shows an embodiment of the present invention. In FIG. 1, 11 is a case divided into two parts, a first case half 11A and a second case half 11B. The second case halves 11A and 11B are fastened to each other by a through bolt 11C with their openings abutting each other.

The case 11 accommodates a load reduction gear mechanism 12 including a gear reduction mechanism having gears 12 a to 12 h. The output shaft 13 of the speed reduction mechanism 12 is supported by the first case half 11A and the second case half 11B via bearings 21 and 21 ', respectively, and is connected to the load of the output shaft 13 at one end 13a. Are led out to the outside through a hole 11B2 provided in the bottom wall portion 11B1 of the second case half portion 11B. The case 11, the gear reduction mechanism 12, and the output shaft 13 constitute a load driving reduction gear 14.

The electric motor 15 is attached to the first case half 11A, and the gear 12a that constitutes the input part of the reduction mechanism 12 is directly engraved on the tip of the rotary shaft 15a of the electric motor 15 inserted into the case 11. ing. The other end of the output shaft 13 is led out to the outside through a through hole provided in the bottom wall 11A1 of the first case half 11A, and the other end of the output shaft 13 led to the outside is the first case half 11A. It is inserted into the sensor driving speed reducer 17 attached to the outer surface of the.

The sensor drive speed reducer 17 has a cylindrical gear 17a directly engraved on the outer periphery of the other end of the output shaft 13 and a spur gear 17b attached to the rotary shaft 17A and meshed with the gear 17a. It is housed in a housing 17B, and the rotating shaft 17A is supported by a housing 17B via bearings.

The housing 17B of the speed reducer for driving the sensor has an end plate 17B1 on one end side in the axial direction of an annular protrusion 11A2 provided on the outer surface of the bottom wall 11A1 of the first case half 11A. The end plate 17B1 is arranged in a state of being fitted to the inner peripheral portion, and is screwed to the bottom wall portion 11A1 of the first case half portion.

The gear 17a carved at the other end of the output shaft 13 is inserted into the housing 17B through a hole provided in the end plate 17B1 and meshed with the gear 17b. The tip 17A1 of the rotary shaft 17A of the speed reducer for driving the sensor is led to the outside through the end plate on the other end side of the housing 17B.

In this example, the inner surface of the annular protrusion 11A2 provided on the outer surface of the bottom wall portion of the first case half is positioned by fitting the end portion of the housing of the sensor driving speed reducer. Make up part. Further, the tip 17A1 of the rotary shaft 17A constitutes an output portion of the sensor driving speed reducer 17.

The inner peripheral portion of the opening end of the sensor support member 18 formed in a cylindrical shape is fitted to the outer peripheral portion of the annular protrusion 11A2, and the sensor support member 18 and the outer peripheral portion of the protrusion 11A2 are fitted together. Thus, the sensor support member 18 is positioned concentrically with respect to the sensor drive speed reducer 17. The sensor support member 18 is fastened to the first case half portion 11A by a through bolt 19 provided by penetrating the peripheral wall portion of the support member in the axial direction. In this example, the spigot portion for positioning the sensor support member 18 is constituted by the outer peripheral portion of the annular projection 11A2.

An endless rotary displacement sensor 16 having no limitation on the rotation angle range of the input shaft is fixed to the end wall of the sensor support member 18 opposite to the sensor drive speed reducer 17 by adhesion or the like. The rotational displacement sensor 16 includes an input shaft 16A and a signal generator 16B that outputs a detection signal corresponding to the rotation angle of the input shaft 16A. A conversion means for converting the rotational displacement amount into an electric signal is housed. This conversion means is composed of, for example, a potentiometer (variable resistor), and can detect the rotation angle of the input shaft 16A of 360 degrees.

The input shaft 16A of the rotational displacement sensor 16 is rotatably supported by a boss 16C fixed to the housing of the signal generator 16B, and the boss 16C is provided on the end wall of the sensor support member 18. It is fitted into the through hole 18a. By this fitting, the input shaft 16A of the rotational displacement sensor and the rotary shaft 17A of the sensor driving speed reducer 17 are coaxially positioned.

The input shaft 16 A of the rotational displacement sensor 16 and the tip portion 17 A 1 of the rotary shaft 17 A of the sensor driving speed reducer 17 are inserted into holes provided in the coupling 20 and screwed in the coupling 20. Screws 20a and 20b screwed into the holes are fastened to the input shaft 16A of the rotational displacement sensor and the rotary shaft 17A of the sensor driving speed reducer, respectively. The coupling 20 is fixed to the input shaft 16A and the rotating shaft 17A by tightening these screws, and the input shaft 16A and the rotating shaft 17A are connected via the coupling 20. In order to enable tightening of the screws 20a and 20b, a window portion 18b is provided through which the peripheral wall portion of the sensor support member 18 is penetrated to insert a driver.

A cylindrical cover 22 that covers the sensor support member 18 and the rotational displacement sensor 16 is provided. The opening end of the cover 22 is fitted and positioned by an annular spigot portion provided on the outer surface of the bottom wall portion 11A1 of the first case half portion 11A. The opening end of the protective cover 22 is also brought into contact with the outer surface of the bottom wall portion of the first case half 11A via the packing 23 so as to project radially outward from the outer peripheral portion of the opening end of the cover 22. An appropriate number of protrusions 22a provided on the first case half 11A are fastened to the first case half 11A by screws 24.

In the present embodiment, the sensor drive speed reducer 17 having the input part coupled to the other end of the output shaft 13 and the output part of the sensor drive speed reducer 17 (the tip 17A1 of the rotary shaft 17A) are connected to the input shaft. The rotary displacement sensor 16 to which 16A is coupled, the support member 18 that supports the rotary displacement sensor 16, the coupling 20, and the protective cover 22 constitute a rotary displacement detector 25.

When the rotational displacement detector 25 is attached, first, the sensor driving speed reducer 17 is attached to the first case half portion 11A, and the gear 17b of the speed reducer is provided at the other end of the output shaft 13. The gear 17a is meshed. Next, with the coupling 20 temporarily fixed to the tip of the rotary shaft 17A of the speed reducer 17, the sensor support member 18 supporting the rotary displacement sensor 16 is attached, and the tip of the rotary shaft 16A of the rotary displacement sensor 16 is attached to the cup. Insert into the hole in ring 20. Next, the screws 20a and 20b of the coupling 20 are tightened through the window 18b of the support member 18 to fix the coupling 20 to the rotary shaft 16A and the rotary shaft 17A of the speed reducer 17. After that, the protective cover 22 is attached, and the assembly of the rotational displacement detector 25 is completed. Since all of these assembling operations can be performed from the axial direction of the output shaft 14, the case 11 is placed on the workbench with the bottom wall 11A1 of the first case half 11A of the case 11 facing upward. Then, by sequentially incorporating the components of the rotational displacement detector 25, the rotational displacement detector 25 can be easily assembled.

Although not shown, the output lead wire of the rotational displacement sensor 16 is led out to the outside through a grommet (rubber bushing) attached to a hole provided through the protective cover 22.

In the above embodiment, the output shaft 13 is connected at its one end 13a to a load (not shown) directly or via an appropriate power transmission mechanism such as a lever or a link. When the electric motor 15 rotates, the output shaft 13 rotates to drive the load, and the rotational displacement sensor 16 is driven via the sensor driving speed reducer 17. Therefore, the rotary displacement sensor 16 outputs a detection signal corresponding to the rotation angle of the input shaft. The magnitude of the rotation angle that can be detected by the rotational displacement sensor 16 is determined by the reduction ratio of the sensor driving reduction gear 17. For example, if the reduction ratio of the sensor drive speed reducer 17 is 10: 1, the input shaft 16A of the rotational displacement sensor 16 rotates once while the output shaft 13 rotates 10 times, so that the output shaft 13 rotates 10 times. The angle (3600 degrees) can be detected.

In the above embodiment, as the rotational displacement sensor 16, an endless sensor in which the rotation angle range of the input shaft is not limited (the input shaft can freely rotate) is used. When the number of times may be limited, it is also possible to use a multi-rotational rotary displacement sensor capable of detecting a rotation angle over many rotations of the input shaft. In this case, the detectable rotation angle range is determined by both the speed reduction ratio of the speed reducer built in the multi-rotation rotary displacement sensor and the speed reduction ratio of the sensor drive speed reducer 17. For example, when a 5-rotation multi-rotation displacement sensor is used as the rotation displacement sensor 16, if the reduction ratio of the sensor drive reduction gear 17 is 1.4, the rotation angle over 7 rotations (360 × 7 Degree) can be detected. Therefore, even if only two types of multi-rotational rotational displacement sensors, a 5-rotational rotational displacement sensor and a 10-rotational rotational displacement sensor, are available, the rotational angle over the intermediate rotational speed is detected. It is possible to increase the degree of freedom in setting the detection range of the rotation angle.

In the above-described embodiment, the electric motor 15 is attached to the first case half 11A of the case 11, but the electric motor 15 is attached to the second case of the case 11 as in the conventional example shown in FIG. It can also be attached to the half portion 11B side.

Although the rotational displacement detector 25 is coupled to the other end of the output shaft 13 in the above-described embodiment, the gear located on the front side of the gear 12h to which the output shaft 13 is coupled (in the example of FIG. 1, in the example of FIG. 1). The rotational displacement sensor 16 may be coupled to the shafts of the gears 12b to 12g) via a sensor driving transmission.

FIG. 2 shows an embodiment in which the rotational displacement detector 25 is connected to the shaft 26 of the front gear 12g (which is also the shaft of the gear 12f) 26 that meshes with the output gear 12h to which the output shaft 13 is connected. Is shown. In this embodiment, the end of the shaft 26 of the gear 12g on the side of the first case half 11A is led out to the outside through a hole provided in the bottom wall 11A1 of the first case half, and It is inserted in the sensor drive speed reducer 17 fixed to the outer surface of the bottom wall portion 11A1 of the case half. In this example, the gear 17a that constitutes the input part of the sensor drive speed reducer 17 is directly carved on the end of the shaft 26, and the gear 17a meshes with the output stage gear 17b of the sensor drive speed reducer 17. There is. The other points are similar to those of the embodiment shown in FIG. 1, and the rotational displacement detector 25 is fixed to the first half 11A of the case 11 with the same structure as that of the embodiment shown in FIG.

In FIG. 2, the same parts as those of FIG. 1 are designated by the same reference numerals.

As shown in FIG. 2, when the rotary displacement detector 25 is connected to the rotary shaft of the gear located on the upstream side of the output stage gear of the load drive speed reducer, the rotary displacement detector is used. 25 can be mounted on the same side as the output shaft 13. For example, in the embodiment of FIG. 2, the rotational displacement detector 25 is attached to the outer surface of the bottom wall portion 11B1 of the second case half portion 11B, and the second case half of the shaft 27 of the gears 12e and 12d shown in FIG. The end portion on the side may be coupled to the input shaft of the rotational displacement sensor via a sensor driving speed reducer.

As shown in FIG. 2, the electric motor 15 can be mounted on the same side as the output shaft 13 even when the rotational displacement detector is connected to the shaft of the gear located on the upstream side of the output stage.

[0056]

[Effect of device]

 As described above, according to the present invention, the output shaft of the load drive speed reducer or the shaft of the gear located on the upstream side of the gear to which the output shaft of the load drive speed reducer is coupled is set to the sensor drive speed reducer. Since it is connected to the input shaft of the rotational displacement sensor via the, it is possible to detect without being limited by the rated detection angle of the rotational displacement sensor by appropriately selecting the reduction ratio of the sensor drive deceleration mechanism. The size of the rotation angle can be set arbitrarily, and there is an advantage that the degree of freedom in setting the angle range to be detected can be increased.

In particular, according to the invention as set forth in claim 7, since the endless type rotational displacement sensor capable of continuous rotation is used as the rotational displacement sensor, continuous rotation of the electric motor is possible, and moreover, many rotations are possible. There is an advantage that the rotation angle can be detected.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 11 Case 11A First Half 11B Second Half 12 Reduction Mechanism for Load Driving 13 Output Shaft 14 Reduction Gear for Driving Drive 15 Electric Motor 16 Rotational Displacement Sensor 16A Input Shaft 17 Reduction Gear for Sensor 18 Sensor Support Member 20 Coupling 22 Protective cover

Claims (8)

[Scope of utility model registration request] 1. A load driving speed reducer in which a load driving speed reducing mechanism is housed in a case, and an electric motor attached to the case and having a rotation shaft coupled to an input portion of the speed reducing mechanism. An electric motor with a speed reducer in which one end of an output shaft of the load driving speed reducer is connected to a load, wherein a sensor driving speed reducer having an input portion coupled to the other end of the output shaft and an input shaft for driving the sensor An electric motor with a speed reducer, comprising: a rotational displacement detector having a rotational displacement sensor coupled to an output portion of the speed reducer and generating a detection signal corresponding to a rotational angle of an input shaft. 2. A load driving speed reducer having a case for accommodating a load driving speed reducing mechanism composed of a plurality of gears, and a rotating shaft attached to the case and coupled to an input portion of the speed reducing mechanism. An electric motor with a speed reducer, wherein one end of the output shaft of the speed reducer is connected to a load, in a gear that constitutes the speed reduction mechanism for driving the load, a front stage of a gear connected to the output shaft. And a sensor drive speed reducer having an input part coupled to the shaft of the gear located on the side, and an input shaft coupled to the output part of the sensor drive speed reducer to generate a detection signal corresponding to the rotation angle of the input shaft. An electric motor with a speed reducer, wherein a rotational displacement detector including a rotational displacement sensor is supported by the case. 3. A case formed by dividing the first case half part and the second case half part into two parts, and arranged so as to face in a facing direction of the first and second case half parts. An output shaft, one end of which is supported by the case via a bearing and connected to a load, and whose one end is led out from the second case half side to the outside; A load drive speed reduction mechanism coupled to the first case half; a motor attached to the first case half and having a rotation shaft coupled to the input part of the load drive speed reducer; A rotational displacement detector attached, wherein the rotational displacement detector has a sensor drive speed reducer having an input part coupled to the other end of the output shaft, and an input part to the output part of the sensor drive speed reducer. With a speed reducer comprising a rotational displacement sensor having a shaft coupled thereto An electric motor. 4. A case formed by dividing the first case half part and the second case half part into two parts, and arranged so as to face the facing direction of the first and second case half parts. An output shaft, one end of which is supported by the case via a bearing and connected to a load, and whose one end is led out from the second case half side to the outside; A coupled speed reducer for driving a load, an electric motor attached to the second case half and having a rotation shaft coupled to an input of the load reducer, and a first case half A rotational displacement detector attached, wherein the rotational displacement detector has a sensor drive speed reducer having an input part coupled to the other end of the output shaft, and an input part to the output part of the sensor drive speed reducer. With a speed reducer comprising a rotational displacement sensor having a shaft coupled thereto An electric motor. 5. A case formed by dividing the first case half part and the second case half part into two parts, and is arranged so as to face in a facing direction of the first and second case half parts. An output shaft, one end of which is supported by the case via a bearing and connected to a load, and whose one end is led out from the second case half side to the outside; A combined gear drive gear reduction mechanism, an electric motor that is attached to the first case half and has a rotation shaft coupled to the input portion of the load drive gear reduction mechanism, and the first case half And a rotational displacement detector attached to the portion, wherein the rotational displacement detector is located on a front side of a gear that constitutes the gear reduction mechanism for driving the load, relative to a gear coupled to the output shaft. Deceleration for driving a sensor in which the input part is connected to the shaft of a rotating gear And a rotational displacement sensor having an input shaft coupled to an output portion of the sensor driving speed reducer. 6. A case formed by dividing the first case half part and the second case half part into two parts, and is arranged so as to face in a facing direction of the first and second case half parts. An output shaft, one end of which is supported by the case via a bearing and connected to a load, and whose one end is led out from the second case half side to the outside; A coupled gear drive gear reduction mechanism, an electric motor attached to the second case half portion and having a rotation shaft coupled to the input portion of the load drive gear reduction mechanism, and the second case half portion. And a rotational displacement detector attached to the portion, wherein the rotational displacement detector is located on a front side of a gear that constitutes the gear reduction mechanism for driving the load, relative to a gear coupled to the output shaft. Deceleration for driving a sensor in which the input part is connected to the shaft of a rotating gear And a rotational displacement sensor having an input shaft coupled to an output portion of the sensor driving speed reducer. 7. The rotation displacement sensor is an endless sensor capable of detecting a rotation angle of 360 degrees of the input shaft without limitation of a rotation angle range of the input shaft. The electric motor with a reducer according to any one of 4, 5, and 6. 8. The sensor drive speed reducer comprises a gear speed reducer, and an input gear thereof is directly engraved on the other end of the output shaft. An electric motor with a reducer according to any one of 7.