JPH048370Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotor used in a speed sensor that is attached to an automobile transmission or the like to detect the vehicle speed of the automobile.

In recent years, in the automobile industry, there has been an emphasis on reducing the weight of automobile parts from the standpoint of resource conservation. For this reason, various attempts have been made to use resin materials in speed sensors for detecting vehicle speeds from the viewpoints of resource saving and weight reduction.

In a type of speed sensor that detects vehicle speed by detecting the rotational speed of the output shaft of a transmission, a rotor shaft is connected to the output shaft, and a permanent magnet is fixed to the outer circumference of the rotor shaft so that the magnet is The magnet is configured to rotate in response to the output shaft, and when the magnet rotates and approaches an adjacent reed switch, the switch is turned on, that is, the reed switch is activated once per revolution of the output shaft. By configuring it to be turned on, the rotational speed of the transmission output shaft is electrically detected and the vehicle speed is detected.

However, in this type of speed sensor device, when the permanent magnet is installed on the rotor shaft, the rotor housing is fixed to the rotor shaft as an intermediate inclusion, but when the shaft rotates at a high speed of 6000 to 7000 rpm. Since the rotor shaft rotates at a high temperature of 140°C and the ambient temperature is as high as 140°C, it is easy for the rotor shaft and rotor housing to become loose, and since permanent magnets are attached to the housing, it is difficult to balance the rotation. There was a problem. In view of these points, conventionally aluminum die-casting has been mainly used as the material for the housing, but this has the disadvantage of high cost.

In consideration of the above-mentioned conventional circumstances and defects, the present invention makes the rotor housing made of resin, and furthermore, by insert-molding a metal plate with an extension part as a balance weight into the housing, it is integrated and supplemented with strength. At the same time, it is an object of the present invention to provide a rotor for a speed sensor that has stable rotational balance and can be manufactured at a lower cost.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 show a first embodiment of the present invention. In the figures, reference numeral 10 denotes a rotor shaft, and its ends include a large diameter portion 11, a medium diameter portion 12, and a small diameter portion 13.
are formed, and there are shoulders 14, 15 between them. And on the shoulder part 15 there is a metal plate 2
0 is fixed by press-fitting or welding, and then a resin rotor housing 30 is insert-molded. In this case, a permanent magnet is cast into the rotor housing 30 and fixed therein. One side of the housing 30 is in contact with the shoulder 14, has a constant thickness, and has a side shape that includes an extension 31 extending in a direction including the plate 20 and an extension extending in a direction including the magnet 40, as shown in FIG. Zaibu 3
2. The holes 33 and 34 on both sides of the magnet 40 are inevitably formed for molding reasons when the magnet 40 is cast into the housing 30. magnet 4
0 may be completely contained within the housing 30, or may be partially exposed. In short, any structure that can be firmly supported by the housing 30 is sufficient.

A hole 21 is formed in the plate 20, and this hole 21 fits into the small diameter portion 13.
Further, the plate 20 is formed with an extension portion 22 that is surrounded by the rotor housing 30. The reason why this extension part 22 is provided is to prevent rotational imbalance from occurring when the shaft 10 rotates due to one permanent magnet 40 being provided in the rotor housing 30. In other words, for balance adjustment, a heavy metal extension 22 is provided as a balance weight on the opposite side of the magnet 40 in the centrifugal direction.

In such a configuration, when detecting the vehicle speed, the rotor shaft 10 rotates around its axis 0 (usually in the range of 0 to 7000 rpm) either integrally with the output shaft of the transmission or via a gear device.
Therefore, the permanent magnet 40 also rotates integrally. A reed switch (not shown), which is a main component of the speed sensor, is provided near the rotor shaft 10 (for example, the position indicated by the two-dot chain line in FIG. 1).
Only when the magnet approaches, the magnet turns on due to magnetic force, current flows, and a signal is sent to a control circuit (not shown). In other words, the reed switch operates once for every revolution of the transmission output shaft.
Since it is turned on, the rotational speed of the output shaft is detected, and the vehicle runs at a predetermined speed which is converted to a vehicle speed by the control circuit.

3 and 4 show a second embodiment, in which the same components as in the previous embodiment are given the same reference numerals. The metal plate 50 is fixed in contact with the shoulder 15 of the rotor shaft 10, and one side of the resin housing 60, in which the permanent magnet 40 is cast, is in contact with the shoulder 14. This is similar to the previous embodiment. However, the plate 50 is formed with a fan-shaped extending portion 51.
differs from the previous embodiment in that it is not covered by the housing 60.

In the second embodiment, because of this configuration, the volume of the housing 60 is smaller than that of the previous embodiment, and there is an effect that resin can be saved. However, since the weight on the side opposite to the side where the magnet 40 is located is lighter, the fan-shaped extension portion 51 is provided to constitute a balance weight.

Note that the holes 52 provided in the plate 50 are provided for this purpose because when molding the resin housing 60, the resin flows into the holes 52 to more firmly integrate the plate 50 and the housing 60. be.

The operation in detecting the vehicle speed in this embodiment is the same as that in the previous embodiment, so a description thereof will be omitted.

In this way, the present invention includes a rotor shaft that rotates at a rotation speed that is the same as or proportional to the rotation speed of the transmission output shaft, and a permanent magnet that is fixed at one end to the rotor shaft and whose other end is in the centrifugal direction. a metal plate having an extension part extending to a side opposite to the rotor as a balance weight; Since the rotor housing is composed of a part of the shaft and a resin rotor housing that includes part or all of the plate, the rotor shaft and the rotor housing are firmly integrated, and there is no possibility that they will separate. . Further, by making the housing made of resin, it is possible to contribute to reducing the weight of the vehicle, and rotational balance can be easily achieved by adjusting the shape of the metal plate having an extension portion as a balance weight. Additionally, the cost is significantly lower than that of conventional aluminum housings.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional front view showing one embodiment of the present invention, Fig. 2 is a left side view of Fig. 1, and Fig. 3 is similar to Fig. 1 showing another embodiment of the present invention. Front view,
FIG. 4 is a left side view of FIG. 3. 10... Rotor shaft, 20, 50... Metal plate, 30, 60... Resin rotor housing, 40... Permanent magnet.

Claims (1)

[Claims for Utility Model Registration] (1) A rotor shaft that rotates at a rotation speed that is the same as or proportional to the rotation speed of the transmission output shaft; A metal plate having an extension part as a balance weight that extends to the side opposite to the side where the magnet is located, and a permanent magnet included in the outer periphery of the metal plate on the opposite side to the extension part. A rotor for a speed sensor, comprising a resin rotor housing that includes a part of the rotor shaft and a part or all of the plate. (2) The rotor for a speed sensor according to claim 1, wherein the extending portion of the metal plate is a plate completely enclosed by a resin rotor housing. (3) The rotor for a speed sensor according to claim 1, wherein the metal plate has a fan-shaped extension, and the extension is a plate exposed from a resin rotor housing.