CN88102290A

CN88102290A - motor with gear

Info

Publication number: CN88102290A
Application number: CN88102290.XA
Authority: CN
Inventors: 海基·塔潘尼·科伊维科
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-04-16
Filing date: 1988-04-16
Publication date: 1988-11-02
Also published as: CN1009692B; CA1295649C

Abstract

The reduction gear (6) is fastened to the body (1) of the geared motor, while the motor stator is fastened to a removable electronic part (13) of the body. The motor rotor (7) is connected to the input shaft (15) of the gear and to an output shaft (20) which projects concentrically through the input shaft. The output shaft (20) according to the invention is mounted in bearings (3, 4) substantially close to the end faces of the housing (1, 13). One end of the output shaft is formed by a flange-shaped cover (2) of the gear, which is mounted in a bearing (3) near the outer periphery of the housing. The gear may be implemented by several stages of friction gears.

Description

Motor with gear

The present invention relates to a mechanical actuator, and more particularly to a geared motor.

Motors and gears and combinations thereof are often used as continuous drives and as actuators to control the number and angle of revolutions of a shaft. In the present invention, this combination also includes a number of sensors and control lines.

Known such combinations are usually assembled from available components such as dc or ac motors, various gear and sensor units and control circuit sections. The combination will then comprise a number of bearings, shaft joints, mounting joints between the parts and cables. The use of this type of assembly therefore entails various recurring problems for the designer, in particular due to the variation of the fixing means and of the dimensions. This also leads to difficulties in the design and installation of the various devices and structures included in this type of combination. Furthermore, the mechanically complex design in the prior art often leads to structural complications when a good rigid structure is required. This type of combined device is therefore both benzene-heavy and labor-intensive in use and maintenance, which results in a major burden in terms of economic efficiency in manufacture.

In fi patent 26230 a combination of a motor and a gear is described, wherein the gear part can be replaced in order to change the transmission ratio. The driven device is connected to a shaft at one end of the motor.

The object of the present invention is to provide an improved and structurally simple combination comprising an electric motor and a gear, which combination is structurally sound, easy to maintain and suitable for use in a wide variety of operating conditions.

According to the invention, a geared motor in which the fixed part of the reduction gear is fastened to the fixed part of a body consisting of a closed housing and in which the motor stator is fastened to the movable end of the body, the motor rotor being connected to the gear with its input shaft and an output shaft extending through and concentrically with the input shaft, is characterized in that: the other end of the output shaft is constituted by a flange-shaped cover of the gear, which is mounted in a bearing near the outer peripheral portion of the housing.

The gear wheel can be, for example, a commercially available planetary gear or friction gear wheel, and, since the input shaft is hollow, it can lead out the output shaft via the input shaft. The output shaft is preferably mounted in bearings at both ends of the box-shaped housing, and the other end of the shaft forms a flange-like cover of the gear unit. The motor with the gear is preferably mounted in a cylindrical housing concentric with the shaft, although other shapes of housing may be used.

The essential features of the invention are described in the respective claims. Various preferred embodiments of the present invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a cross-sectional view showing a preferred embodiment of the geared motor of the present invention;

FIG. 2 shows another embodiment of the present invention, and

figure 3 shows a further developed motor with a triple gear.

The stationary part 1 of the housing in fig. 1 is fixed to the circumference of the structure supporting the geared motor by means of stops 17, which may be, for example, screws. The fixed part of the gear is fixed to the fixed part 1 of the housing, while the output end of the gear is connected to the output flange 2 of the output shaft 20, to which flange 2 the components driven by the motor/gear are fastened. The flange 2 is preferably formed as one piece with the shaft 20.

The input shaft 15 is rotated by the rotor 7 of the electric motor, which is fixed to the shaft, and the stator of the electric motor is fixed to the removable part 13 of the housing. The input shaft 15 is mounted in bearings in the body 1 and the flange-shaped cover 2 of the gear transmission. For good stability of the output shaft, the output shaft is located in a bearing 3 near the circumferential end flange and the other end is mounted in a bearing 4. The stator 8 of the motor, the sensors 9 and the circuits 11 are fixed to a removable portion 13 of the body for control and manipulation according to various needs. A suitable motor is a dc motor, the method of rotation and the number of revolutions and the rate of the rotational movement of which are controlled via line 11, for example, in dependence on signals from a control cable. The portion 13 is secured against the bearing 4 by a nut 5 screwed onto the thread of the output shaft to the circumferentially opposite portion of the body along point 16. The connection cables for the power supply of the motor and the cables for the sensors and control lines all open into the body through the inlet 12.

The detachable electronic part 11 of the body is removed again for maintenance or other purposes by unscrewing the nut 5, and the whole part 13, including the internal components, can then be removed along the separating surfaces 14-14 in a simple manner. To facilitate the disassembly process, each cable is provided with a suitable connector.

When the part 13 is removed or possibly replaced, the motor rotor 7, the sensor rotor 10, the bearing 3 and the reduction gear 6 remain stationary.

It is appropriate to fix the sensor rotors 10 and 20' to the input and output shafts, whereby information can be provided via the sensor 9 for controlling the rotational speed, the number of revolutions, the direction of rotation, the angle of rotation or related quantities. The sensors may be commercially available or may require a special design for the sensor.

Since the sensor rotor can be mounted on the input shaft as well as on the output shaft, it is possible to monitor and control the operation of the motor and gears in a variety of ways.

When a longer distance between the two bearings is required, the removable portion 13 of the body is wide, thus providing the space required for the control of the motor, for example for the power supply of the motor, and for other useful adjustment means, which may be assembled from commercially available components and/or made of components specifically designed for this purpose.

Another embodiment of a geared motor having advantages is shown in fig. 2. Wherein like reference numerals are used to refer to like parts used in figure 1. The main difference is that in practice the reduction gear is constituted by a friction gear 30 realized by a number of steel balls 30, which steel balls 30 in turn constitute the bearings of the flange-shaped cover 2. A friction gear of this type is described in fi patent No. 7136. In the present invention, the steel balls 30 are arranged at equal distances from each other on the raceway surfaces arranged along the steel balls. The steel ball 30 constitutes a bearing corresponding to the bearing 3 in fig. 1. They further constitute a gear wheel 6. These balls abut two surfaces 31 in grooves provided in the rotor, one surface 32 in the body 1 and one surface 33 in the output flange. The

surfaces

31, 32, 33 in the cross-sectional view of fig. 2 form a circular track when the motor is in operation. The gear ratio of the gear is determined by the distances of the

surfaces

31, 32, 33 to the axis 34 of the shaft and the mutual relationship between these distances.

The motor/gear described above may be further configured such that the

bearings

30, 3, 4 of the output shaft 20, and the

gaskets

19, 22, 23, 24 between the parts of the housing, and the inlet gasket, are liquid tight. In this construction the entire interior of the body is filled with a suitable liquid, such as a water-propylene glycol solution, so that it is possible to place the motor/gear in water or an environment containing fretting gases by the combined action of the liquid and the spacer. Or only a portion of the body may be filled with liquid.

The components of the gear train may be sealed as required by 22, 23 and 24. The gear may also be operated in dry conditions, so that no sealing is required.

The transmission ratio is difficult to predetermine for this type of arrangement with friction gearing, partly due to tolerances in the manufacture of the parts and partly due to wear of the parts during operation. However, the change in transmission ratio that occurs during operation is not problematic, since the motor/gear according to the invention is controlled by information from the

sensors

10, 20' and 9. The control electronics 11 may be provided with a feedback system so that the number of revolutions or angle of rotation of the output shaft 20' can be accurately controlled irrespective of changes in the gear ratio.

On the other hand, the change in transmission ratio sensed by the

sensors

9, 10, 20' can be used to monitor the motor/gear during long-term operation and for example for adjustment of bearing play.

These variations are substantially completely avoided when the material of the steel ball and the material of the surfaces in contact therewith have been selected and dimensioned by means of suitable methods.

Referring to fig. 3, the bearing employed is the same as the friction bearing structure shown in fig. 2, but a three-stage structure is shown as an example. But two, four, five, etc. stages may be employed. The same parts as those shown in fig. 2 are denoted by the same reference numerals.

The steel balls in the different stages of the gear are indicated by

reference numerals

30, 30', 30 ". The input shaft for each gear stage is indicated by

reference numerals

15, 15 ', 15 "and its spacers by

reference numerals

24, 24' and 24". The reduction gear is made up of several coaxial friction gears realized with

steel balls

30, 30', 30 ".

Each gear stage may have a gear ratio determined by the radius of its respective contact surface. In this embodiment, the gear ratio of each gear stage may be 16: 1, whereby the overall gear ratio given is 4096: 1.

The input shaft and the output shaft of each gear stage can be configured with

sensor rotors

10, 10 'and 10 ", 20', i.e.

sensor rotors

10, 10 ', 10", 20' are arranged on the shafts of each gear stage, so that the above-mentioned control and monitoring functions are realized by means of a feedback line.

The motor/gear of the present invention may be suitably configured with a hollow output shaft 20 as shown in the figures. Depending on the application, the axial support members, the rotating shaft, the cables and pipes, as well as the pipes for liquids and gases, may be introduced through the body of the device either as a functional part of the or each device driven by the motor/gear or as a separate unit.

When a member with an internal thread is mounted to the inside of the hollow output shaft 20, the rotational movement of the output shaft of the motor/gear can be converted into a directly controllable axial movement into the output shaft, not shown.

The rotary motion controlled by the

sensors

9, 10, 20 and the control electronics can be precisely defined, even up to a few percent of a revolution, or extend to a continuous rotary motion at a controlled speed. Due to the relationship between the transmission ratio of the reduction gear and the pitch of the screw thread described above, the spindle moving in the hollow shaft can be controlled precisely with a set accuracy in preference to 0.01 mm even in the case of single-stage gears.

A geared motor can be used as both a rotary and an axial actuator, with a gear ratio of between 5: 1 and 10,000: 1 being optional.

Claims

1. A geared motor in which the fixed part (6) of the reduction gear is fastened to the fixed part (1) of a body consisting of a closed housing (1, 13), and in which the motor stator is fastened to the movable end (13) of the body, and the motor rotor (7) is connected to the gear with its input shaft (15) and an output shaft (20) extending through and concentrically with the input shaft, characterized in that: the other end of the output shaft is formed by a flange-shaped cover (2) of the gear wheel, which is mounted in a bearing (3) near the outer circumferential part of the housing.

2. The geared motor of claim 1, wherein: the reduction gear is formed by a friction gear realized by a plurality of steel balls (30), and the steel balls (30) form the bearing of the flange-shaped cover (2).

3. The geared motor of claim 2, wherein: the reduction gear is made up of several coaxial friction gears realized in steel balls (30, 30').

4. The geared motor of claim 1, wherein: the end (13) is integrally detachable and comprises a sensor (19) and an electronic control circuit (11) arranged around the shafts (15, 20), while the sensor rotor (10) can be arranged on both the input shaft (15) and the output shaft (20) of the gear.

5. The geared motor of claim 4, wherein: the sensor rotors (10, 10 ', 20') are arranged on the shafts of each gear stage.

6. A geared motor as claimed in any one of claims 1 to 13, wherein: the bearings (30; 3, 4) of the output shaft (20), the gaskets (19; 22, 23, 24) between the housing parts, and the inlet gasket (18) are all liquid-tight, and the geared motor is completely or partially liquid-filled.

7. The geared motor according to any one of claims 1 to 6, wherein: the output shaft (20) is hollow.

8. The geared motor of claim 5, wherein: by screwing a component on the inside of the output shaft (20), the rotational movement of the output shaft (20) can be converted into a directly controllable axial movement of the spindle which projects into the output shaft.