JPH0725700Y2 - Rotation detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a rotation detecting device, and in particular, it is mounted on a transmission of an automobile, etc. Regarding a detection device.

[Conventional technology]

Conventionally, as a vehicle speed sensor mounted on an automobile, the rotation of the transmission of the automobile is transmitted to a magnet arranged close to the magnetic sensitive element, and the change in the magnetic field due to this rotation is detected by the magnetic sensitive element to detect the magnetic field. A power generation type rotation detection device that outputs an electric signal generated by a sensitive element to various indicating instruments is often used.

FIG. 4 shows a conventional rotation detecting device. This rotation detecting device 1 has a cylindrical housing 2 in which a rotating portion 3 and a power transmitting portion 4 are integrated. Built into.

A rotor 5 is rotatably arranged on the rotating portion 3, and the rotor 5 has, for example, a peripheral surface portion 5a magnetized in multiple poles. An input rotary shaft 7 rotatably supported by a bearing 6 is fitted in the center of the rotor 5, and the input rotary shaft 7 has a hollow portion 8 having a rectangular cross section.
Are formed. A coupling portion 9a having a quadrangular cross section of a coupling 9 connected to a rotary drive source of a transmission (not shown) is fitted in the hollow portion 8 so that the rotor 5 can rotate the transmission. It is designed to be transmitted.

Further, a magnetic sensitive element 10 such as a Hall element is arranged in the power transmitting section 4 in the vicinity of the rotor 5, and the magnetic sensitive element 10 and the peripheral surface 5a (magnetized surface) of the rotor 5 are arranged. It is designed to face and. Further, a board 11 to which an electric signal generated by the magnetic sensitive element 10 is input is provided, and the electric signal from the board 11 is sent to a not-shown indicating instrument or the like via a lead wire 12. There is.

In such a rotation detecting device 1, the rotor 5 may rotate and move with a slight width due to the backlash generated at the connecting portion between the rotary drive source of the transmission and the coupling 9, and the rotor 5 may be stopped or run at a low speed. When vibration or shock is applied to the vehicle, the rotation of the transmission is not sufficiently transmitted to the rotor 5 due to the shake of the rotor 5 due to the rattling, but the electric signal from the magnetic sensitive element 10 indicates that the rotor 5 has rotated. It was sometimes output incorrectly. Therefore, the rotation detecting device 1 is provided with a thrust washer 13 that presses the rotor 5 toward the bearing 6 and a spring 14 that biases the thrust washer 13 as a braking mechanism that prevents the rotor 5 from shaking. The thrust washer 13 and the end surface 5b of the rotor 5 are
By the surface contact with, the predetermined braking force obtained by multiplying the friction coefficient of the thrust washer 13 by the load of the spring 14 is obtained, and this braking force prevents the malfunction caused by the shake of the rotor 5.

The braking force by the spring 14 is such that a constant torque is always generated regardless of the vehicle speed, as shown in FIG.

[Problems to be solved by the device]

However, as shown in FIG. 6, the braking force does not require so much torque in the high speed running state as long as sufficient torque is obtained in the stop or low speed running state where the influence of the shake of the rotor 5 is great. On the other hand, in the above conventional rotation detecting device, the friction coefficient of the thrust washer 13 and the spring 14 are irrespective of the vehicle speed.
Since a constant braking force is obtained by multiplying the load of No. 1, the braking characteristic originally shown in FIG. 6 cannot be obtained due to its structure, and the load of the spring 14 is always the thrust washer 13 However, there is a problem in terms of durability due to the above-mentioned effects, and there is also a problem that the braking force decreases with time due to the fatigue of the spring 14, wear, or the like.

The present invention has been made in view of the above-mentioned points, and it is possible to improve the durability of a braking mechanism that prevents the shake of the rotor by obtaining the originally required braking characteristics, and it is possible to detect rotation with sufficient reliability. The purpose is to provide a device.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, a rotation detecting device according to the present invention comprises a rotor having a magnetic force, which is rotatably disposed in the housing in the vicinity of a magnetic sensitive element, and the rotor is provided with a rotation output source through a coupling. In the rotation detecting device connected to, at least one of the housing and the rotor is provided with a braking magnet, a magnetic circuit including the braking magnet is formed across the housing and the rotor, and an attractive force generated in the magnetic circuit. The rotor is brought into pressure contact with the housing by means of the above, and a temperature-sensitive magnetic material whose magnetic permeability is lowered by heat generated in the pressure contact portion between the rotor and the housing is interposed in the magnetic circuit.

[Action]

According to the present invention, a braking magnet is provided on at least one of the housing and the rotor, and a magnetic circuit including the braking magnet is formed across the housing and the rotor.
Since the rotor is brought into pressure contact with the housing by the attraction force generated in this magnetic circuit, and the temperature-sensitive magnetic material whose magnetic permeability is lowered by the heat generated in the pressure contact portion between the rotor and the housing is interposed in the magnetic circuit, The braking force of the suction force prevents the rotor from shaking and prevents the malfunction of the rotation detecting device.

Further, since the magnetic permeability of the temperature-sensitive magnetic material provided in the magnetic circuit decreases due to frictional heat generated in the pressure contact portion between the rotor and the housing, the decrease in the magnetic permeability causes the attraction force in the magnetic circuit. When the rotor rotates at a high speed and a large frictional heat is generated in the pressure contact portion, the braking force by the suction force does not act much. Therefore, sufficient braking torque can be obtained only when the rotor is rotating at a low speed, which is greatly affected by the shake of the rotor, that is, when the vehicle is stopped or in a low-speed running state.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3, and the same parts as those in the prior art will be designated by the same reference numerals.

FIG. 1 shows an embodiment of the present invention, in which a rotor 5 made of synthetic resin mixed with magnet powder is rotatably arranged in a cylindrical housing 2. Multi-pole magnetization is radially applied to one end surface 5c side portion of the rotor 5, and a yoke plate 15 made of a temperature-sensitive magnetic material is fixed to the other end surface 5d of the rotor 5. In the portion of the rotor 5 facing the multipolar magnetized end surface 5c,
A magnetically sensitive element 10 such as a Hall element is arranged close to the magnetically sensitive element 10. The magnetically sensitive element 10 detects a change in the magnetic field due to the rotation of the rotor 5 and sends a predetermined electric signal to an indicator, not shown. Has been done.

Further, in the portion of the rotor 5 facing the yoke plate 15,
A cylindrical braking magnet 16 fixedly provided in the housing 2 is disposed in close proximity thereto, and is disposed inside the braking magnet 16 so as to form a substantially U-shaped cross-section together with the braking magnet 16. A cylindrical bearing metal 17, such as iron-based sintered material, facing the yoke plate 15 is fitted. Further, one end of an input rotary shaft 7 rotatably supported by the bearing metal 17 is fitted into the center portion of the rotor 5 from the yoke plate 15 side, and the other end of the input rotary shaft 7 is inserted. The part is designed to act as a coupling 9 connected to a rotary drive source of a transmission (not shown). Further, between the yoke plate 15 of the rotor 5 and the bearing metal 17,
A plurality of thrust washers 13 are interposed, and the thrust washers 13 are configured to fill the gap formed between the yoke plate 15 and the bearing metal 17.

Next, the operation of this embodiment will be described.

In this embodiment, the rotation detecting device 1 is mounted on a transmission of an automobile, the rotation of the transmission is transmitted to the rotor 5 via the coupling 9 and the input rotary shaft 7, and the change of the magnetic field due to the rotation of the rotor 5. Is detected by the magnetically sensitive element 10 and an electric signal generated by the magnetically sensitive element 10 is output to a predetermined indicating instrument, whereby a speed display or the like according to the value of the electric signal is performed.

In this case, a magnetic circuit passing between the housing 2 on the fixed side and the rotor 5 on the rotating side and passing through the braking magnet 16, the yoke plate 15, the thrust washer 13, and the bearing metal 17 across the housing 2 and the rotor 5. Are formed,
As a result, the braking magnet 16 and the yoke plate 15 are attracted to each other with the thrust washer 13 sandwiched therebetween, and the rotor 5 side is pressed against the housing 2 side. Then, a braking force obtained by multiplying the attraction force generated in the magnetic circuit by the friction coefficient of the thrust washer 13 acts on the rotor 5 side. This braking force prevents the rotor 5 from swaying. The rotation detection device is prevented from malfunctioning when the vehicle is stopped or running at a low speed.

Further, since the yoke plate 15 through which the magnetic circuit passes is formed of a temperature-sensitive magnetic material, the rotor 5 rotates at a high speed and a large friction is generated by the thrust washer 13 which is the pressure contact portion between the rotor 5 side and the housing 2 side. When heat is generated, the frictional heat raises the temperature of the yoke plate 15 and lowers its magnetic permeability, weakening the attractive force in the magnetic circuit and causing the braking force not to act much on the rotor 5 side. Like

That is, as shown in FIG. 2, assuming that the braking force due to the attraction force of the magnetic circuit while the vehicle is stopped is 200 g-cm, the pressure contact portion between the rotor 5 side and the housing 2 side running at 100 km / h. The temperature rise due to the frictional heat of 40 ° becomes 40 deg, the magnetic permeability of the yoke plate 15 made of the temperature-sensitive magnetic material drops to μ≈2000, and the braking force due to the attraction force becomes about 75.
It drops to g-cm. Further, when traveling at a speed of 200 km / h, the magnetic permeability becomes μ = 0 and the yoke plate 15 is no longer a magnetic substance, and no attractive force is generated between the braking magnet 16 and the yoke plate 15, so that the braking force is not generated. Does not work at all. Further, the temperature rise due to the frictional heat at the pressure contact portion rises as shown by the straight line A in the initial state as shown in FIG. The power also drastically decreases as shown by the curve C in the initial state in conjunction with the temperature rise, but thereafter becomes stable as shown by the curve D. And the curve D of this braking force is
The braking characteristic becomes similar to that shown in FIG. 6 described above, and sufficient braking torque can be obtained only when the rotor 5 rotates at a low speed, which is greatly affected by the shake of the rotor 5, that is, when the vehicle is stopped or in a low speed running state. Therefore, when the rotor 5 rotates at a high speed, the braking force by the suction force does not act much.

Therefore, in the present embodiment, the shake of the rotor 5 can be prevented by the braking force by the attraction force of the braking magnet 16 instead of the biasing force by the conventional spring, and thus the malfunction of the rotation detection device can be prevented. Since the degree of deterioration over time of the braking magnet 16 is smaller than the degree of fatigue of the conventional spring, a stable braking force can be obtained forever, and the durability and reliability of the rotation detection device can be improved. .

Further, since the yoke plate 15 made of the temperature-sensitive magnetic material is provided in the magnetic circuit by the braking magnet 16, it is sufficient only when the rotor 5 is rotated at a low speed, that is, when the vehicle is stopped or the vehicle is running at a low speed. A sufficient braking torque is obtained, and the braking force due to the suction force does not act so much in a high-speed running state of the vehicle in which the rotor 5 rotates at a high speed, whereby the optimum braking required for the braking mechanism of the rotation detection device is obtained. The characteristics can be obtained, and the influence of heat can be prevented by preventing an excessive temperature rise due to frictional heat at the pressure contact portion between the rotor 5 side and the housing 2 side, which also contributes to the durability of the rotation detection device. The reliability and reliability can be improved.

FIG. 3 shows another embodiment of the present invention, in which the other end surface 5d of the rotor 5 has a yoke plate 15 made of a temperature-sensitive magnetic material.
Instead of being fixed, the end surface 5d is magnetized in a two-pole ring shape having an N pole at the inner peripheral portion and an S pole at the outer peripheral portion, and the other end surface 5d side of the rotor 5 is configured as a braking magnet. Cylindrical temperature-sensitive magnetic material fixed to the housing 2 at a portion facing the
18 and a cylindrical bearing metal 19 such as iron-based sintered material are arranged. Even in this case, the same operation and effect as those of the above-described embodiment can be obtained, and since the yoke plate 15 is not necessary, the axial length of the entire device can be further shortened,
The cost can be reduced.

[Effect of device]

As described above, in the rotation detecting device according to the present invention, at least one of the housing and the rotor is provided with a braking magnet, and a magnetic circuit including the braking magnet is formed across the housing and the rotor. Since the rotor is brought into pressure contact with the housing by the attraction force generated in the above, and the temperature-sensitive magnetic material whose magnetic permeability is lowered by the heat generated in the pressure contact portion between the rotor and the housing is interposed in the magnetic circuit, the attraction force is It is possible to prevent the rotation of the rotor from being shaken by the braking force due to The torque can be obtained, and the durability and reliability of the rotation detection device can be improved by obtaining the originally required braking characteristics. The effect of, or the like can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view of an essential part showing an embodiment of the present invention, and FIG. 2 is a braking characteristic, a friction heat temperature rise characteristic of the above embodiment,
FIG. 3 is a side sectional view showing a main portion of another embodiment of the present invention, and FIG. 4 is a side sectional view showing a conventional rotation detecting device. FIG. 5 is a diagram showing a conventional spring type braking characteristic, and FIG. 6 is a diagram showing a braking characteristic originally necessary for a rotation detection device. 1 ... Rotation detecting device, 2 ... Housing, 5 ... Rotor, 7 ...
Input rotary shaft, 10 ... Magnetic sensitive element, 13 ... Thrust washer, 14 ... Spring, 15,18 ... Temperature-sensitive magnetic material, 16 ... Braking magnet, 17, 19 ... Bearing metal.

Claims (1)

[Scope of utility model registration request] 1. A rotation detecting device in which a rotor having a magnetic force is rotatably disposed in the housing in the vicinity of a magnetically sensitive element, and the rotor is connected to a rotation output source via a coupling. A braking magnet is provided on either one of the housing or the rotor, a magnetic circuit including the braking magnet is formed across the housing and the rotor, and the rotor is pressed against the housing by an attractive force generated in the magnetic circuit. A rotation detecting device characterized in that a temperature-sensitive magnetic material whose magnetic permeability is lowered by heat generated in a pressure contact portion between the rotor and the housing is provided in the magnetic circuit.