WO2004004097A1 - Commutatorless dc motor or universal motor - Google Patents

Abstract

A commutatorless dc motor using slip rings (8) and brushes (16) to supply power to the coil (3) of a rotor (1). A plurality of slip rings (8) insulated from each other are fixed around the periphery of the rotary shaft (4) of the rotor (1), the ends (3a, 3b) of the coils (3) of the rotor (1) are respectively connected to the slip rings (8), and the brushes (16), which are always in contact with the slip rings (8), are fixedly disposed around the periphery of the rotary shaft (4). The slip rings (8) and brushes (16) are received in a vessel (22) and lubricated with lubricating oil having insulation property. The timing for energizing the coils (3) is controlled by a switching circuit including switching elements. It is possible to reduce the wear in the slip rings (8) and brushes (16) and to improve the life of the dc motor.

Description

 Description Non-commutator type DC motor or universal motor

 The present invention relates to a non-commutator type DC motor or a universal motor that uses a slip ring connected to the end of a coil at the mouth instead of the commutator of a commutator type DC motor or a universal motor. Background art

 The commutator-type DC motor has the advantage that the power is large even if it is small and lightweight, and the operating energy conversion efficiency for the supplied power is the highest level among various motors.

 Therefore, it can be said that there are potential possibilities for use in electric vehicles, electric wheelchairs, electric bicycles, etc., which require efficient use of the limited power stored in the battery. The characteristic that the smaller the value is, the larger the generated torque is, is also suitable for use in electric vehicles.

 However, the commutator type DC motor supplies power by the sliding contact between the commutator and the brush, which rotates with the rotor, and has the following problems.

(1) The brush and commutator wear quickly, and sparks and heat are generated, and the oxidation of the material surface based on the spark and heat promotes this wear. If worn, brushes and commutators can be replaced, but this is often inconvenient and the life of motors is short.

 (2) A certain pressure is applied to the brush and it comes into contact with the surface of the commutator. However, for some reason, poor contact may occur and the motor may not run. It is dangerous if the motor stops while driving in a car or the like.

 ③ Sparks cause electrical noise. There is a risk of affecting the control system of the vehicle.

As a means to solve these problems of the commutator type DC motor, the mechanical switching mechanism consisting of the brush and the commutator is replaced with an equivalent electronic circuit switching mechanism. There is an idea that you can get.

 One is a so-called brushless motor, in which the coil is fixed to the stay side and the permanent magnet rotates as a rotor. However, this brushless motor has a large inertia and poor response, and is not suitable as an automobile motor that repeatedly starts, stops, accelerates and decelerates, and its energy conversion efficiency in that case is also poor.

 The other uses a slip ring and a brush that is in constant contact with it, pulls out the rotor coil, connects it to the slip ring (two slip rings per coil), and connects to the coil by a switching mechanism in the electronic circuit. It controls the energization of the battery.

 In the latter case, since the slip ring and the brush are in constant contact, there is no spark, which is the main cause of electrical noise, and there is an advantage that heat is reduced accordingly. Therefore, wear of the slip ring and the brush is relatively suppressed. In addition, since a dedicated brush comes into contact with each slip ring, poor contact can be reduced. However, the point where there is mechanical contact is the same as that of the conventional commutator type DC motor, and wear due to sliding contact exists. In addition, heat is generated due to the sliding contact, and the oxidation of the material surface is accompanied by the heat. Therefore, no significant improvement in wear is expected, and the level of improvement in motor life is not large. Disclosure of the invention

 SUMMARY OF THE INVENTION An object of the present invention is to reduce the wear of a slip ring and a brush and to improve the life of a motor when power is supplied to a coil of a rotor of a DC motor using the slip ring and a brush.

According to the present invention, a plurality of insulated slip rings are fixed around a rotating shaft of the mouth, and the ends of the coils of the roving are connected to the slip rings, respectively. In a non-commutator type direct current motor in which a brush that is constantly in contact with a slip ring is fixedly arranged and a current is supplied to each coil of the rotor through the brush and the slip ring, the slip ring and the brush surround the brush. It is housed in a container and is lubricated with an insulating lubricating oil in the container. According to the present invention, a film of lubricating oil is formed between the slip ring surface and the brush, heat generation is also reduced, and brush wear is dramatically reduced. Lubricating oil is insulative, but if the contact pressure of the brush is set appropriately, a portion of the contact surface between the slip ring and the brush where the lubricating oil film breaks will be formed, and the current will flow through it. Flows continuously.

 The specific method of lubrication is arbitrary, and typical examples are immersion method (part of the slip ring (and, in some cases, part of the brush) immersed in lubricating oil collected in a container), spraying Method (spray lubricating oil in a container, and the fine particles adhere to the surface of the slip ring). Further, the container may be filled with an inert gas. It is desirable that the lubricating oil in the container be pumped up and circulated through the oil filter and oil cooler.

 Further, the container may be filled with an inert gas instead of the insulating lubricating oil. In this case, the effect of reducing the wear by lubrication cannot be obtained, but even if heat is generated by the sliding contact, the oxidation of the slip ring and the brush can be prevented, and the improvement in wear can be expected.

 In the non-commutator type DC motor, the action of the commutator and the brush needs to be replaced by a switching mechanism using an electronic circuit, and a detecting means for detecting the position of the rotor; and A switching circuit for controlling the energization of the coil will be provided.

 The present invention can be similarly applied to a universal motor (a non-commutator type universal motor). BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a schematic plan sectional view of a non-commutator type DC motor according to the present invention. Figure 2 is a cross-sectional view of the I-I arrow (only the main part).

 Fig. 3 is a schematic diagram of the drive and control system. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a non-commutator type DC motor according to the present invention will be described with reference to FIGS. This will be described more specifically.

 In FIG. 1, the mouth 1 is composed of a core 2 and a coil 3 wound in its slot (in this example, the number of coils is 6), and a stay composed of a permanent magnet is not shown. A rotating shaft 4 of the rotor 1 is supported by bearings 5 and 6, and around the rotating shaft 4, 12 slip rings 8 are fixed insulated from each other via an insulator 7.

 On the other hand, two conductors 3 a and 3 b extend from the six coils 3 respectively, are supported by a rotating support 11 fixed to the rotating shaft 4 via an insulator 12, and further extend outside. The tip is fixed to each of the slip rings 8. The rotary support 11 is rotatably supported by a bearing 13.

 As shown in FIG. 2, each slip ring 8 is formed with a hole 14 through which the conductors 3a and 3b of each coil 3 pass, and the conductors 3a and 3b whose ends are not fixed there are formed therein. It is insulated from the slip ring 8 via the insulator 15 and passes therethrough and is fixed to the slip ring 8 ahead. This is repeated, and the ends of the conductors 3 a and 3 b of the six coils 3 are connected to 12 insulated slip rings 8, respectively.

 A ring-shaped brush 16 is arranged in contact with each slip ring 8. The brush 16 is fixed inside an insulating support member 17, and the support member 17 is further fixed inside a container 22 described later. Further, a leaf spring 18 is fixedly disposed on the support member 17 near each brush 16, and the urging force of this leaf panel 18 presses the brush 16 against each slip ring 8, and both of them are in a predetermined state. It comes into contact with the contact pressure.

 Each slip ring 8 is provided with a mounting portion 21 for connecting a conducting wire 19 for supplying electric power from outside.

Further, a container 22 surrounding the slip ring 8 and the brush 16 is provided, which is disposed around the rotary support 11 and the rotary shaft 4 via oil seals 23, 24. . Insulating lubricating oil is sprayed into the container 22 in a mist by a spray device (not shown) to wet the surfaces of the slip ring 8 and the brush 16, and the lubricating oil collected at the bottom of the container 22 is pumped by an oil pump (not shown) Sucked up by container 2 2 Circulates through the oil filter and oil cooler installed outside, and is sprayed into the container 22 again.

 Fig. 3 schematically shows the drive and control system of this DC motor, and shows a low-speed re-encoder 25 (a slit disk 26 fixed to the rotating shaft 4 and rotating together, a light-emitting diode 27 and a photo diode). The position signal of the mouth 1 from the transistor 28) is sent to a drive / control device 29 having a switching circuit. The switching circuit of the drive / control device 29 includes a switching element and is an electronic circuit that replaces the conventional mechanical switching using a commutator and a brush, and is known per se. The drive / control device 29 performs on-off and commutation of the current flowing through each coil 8 at a predetermined timing by the switching circuit based on the position signal from the single tally encoder 25. In FIG. 3, reference numeral 30 denotes a DC power supply.

 Since the commutator type DC motor is a mechanical switching mechanism using a commutator and a brush, the on-off and commutation timing of the current flowing through each coil is always performed as initially set. In the non-commutator type DC motor, the plurality of coils of the rotor are individually controlled by the switching circuit, so that the timing can be arbitrarily selected and set. In addition, the voltage applied to the coil can be controlled for each coil.

 ADVANTAGE OF THE INVENTION According to this invention, in a non-commutator type DC motor which supplies electric power to a coil of a DC motor using a slip ring and a brush, the wear of a slip ring and a brush is reduced, and the life of the motor is reduced. The use of DC motors, which can be extended and have high kinetic energy conversion efficiency, can be extended to electric vehicles, electric wheelchairs, electric bicycles, and the like.

 In addition, since the commutatorless DC motor is controlled by a switching mechanism using an electronic circuit, the on / off and commutation timing, voltage, etc. of the current can be arbitrarily controlled for each coil. The absence of electrical noise and no noise is also suitable for the above applications.

Claims

The scope of the claims 1. A plurality of slip rings insulated from each other are fixed around the rotation axis of the mouth and the mouth, and the ends of the coils of the mouth and the night are connected to the slip rings respectively. A non-commutator type DC motor or a universal motor in which a brush that is in constant contact with the motor is fixedly arranged so as to energize each coil of the rotor through the brush and the slip ring, and the slip ring and the brush surround these. A non-commutator type DC motor or universal motor, which is housed in a container and lubricated in the container with an insulating lubricating oil. 2. The non-commutator type DC motor or universal motor according to claim 1, wherein the container is filled with an inert gas instead of an insulating lubricating oil.  3. The non-commutator type according to claim 1 or 2, further comprising a detecting means for detecting a position of the rotor, and a switching circuit for controlling energization of the coil based on a signal from the detecting means. DC motor or universal motor.