JPH0541363Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a rotation angle sensor for internal combustion engines.
In particular, it relates to an advantageously formed ring magnet, which is a component thereof.

[Prior Art] A conventional rotation angle sensor for an internal combustion engine includes a cylindrical ring magnet, a sensor unit for detecting the rotation of the magnet, and the like housed in a housing.

A typical ring magnet is made of ferrite which is sintered into a cylindrical shape, and a predetermined portion of its outer surface is magnetized. When this ring magnet rotates, a sensor unit detects the magnetized portion and measures the rotation angle by outputting a signal pulse.

[Problems to be solved by the invention] By the way, the ferrite that forms the ring magnet is expensive and has the characteristics of being weak against heat. For example, if the temperature difference is about 200°C, cracks are likely to occur due to residual stress due to molding distortion, which leads to problems such as difficult molding conditions and poor durability.

Additionally, in order to use a ring magnet as a rotation sensor, it must be coaxially attached to the shaft. In order to fix the ring magnet to the shaft so that it can rotate at high speed, in the case of ferrite magnets, etc., it is necessary to provide a notch in the ring magnet and fill the gap with resin etc. to prevent them from coming apart. Stress concentrates on the parts, making them more likely to break. Even if you do not use a ferrite magnet, it is necessary to set the ring magnet and shaft so that they are coaxial and to connect them by filling the space between them with a substance with a different coefficient of thermal expansion. , the number of stress concentration points increases, making it more likely to break.

Therefore, the present invention aims to provide a rotation angle sensor for an internal combustion engine that has a ring magnet that is easy to mold and has good durability.

[Means for Solving the Problems] The rotation angle sensor for an internal combustion engine of the present invention includes a cylindrical ring magnet whose outer surface is partially magnetized, and a cylindrical ring magnet that is placed close to the ring magnet and that rotates the magnet. A sensor unit for detecting an angle is housed in a housing, and the ring magnet has one end attached to an inner cylindrical part attached around a shaft connected to an internal combustion engine, and a radial distance from this inner cylindrical part. It comprises a plurality of fins extending radially outward in the direction and an outer cylinder part connected to the inner cylinder part via the fins, and the inner cylinder part, the fins and the outer cylinder part are integrally formed, At least the outer surface of the outer cylinder part is made of resin mixed with a magnetic substance, and the inner cylinder part is molded around the shaft to be integrated with the shaft. The retaining part is formed by fitting a part of the part into a concave or convex part formed on the shaft side when the part is molded.

[Operation of the invention] The ring magnet constituting the rotation angle sensor for an internal combustion engine of the invention includes an integrally formed inner cylinder part,
It has fins and an outer cylinder. Moreover, the inner cylinder part is integrated with the shaft during molding and is strongly connected.
At the portion where the inner cylinder part and the shaft connect, a retaining part is formed, at the same time as the inner cylinder part is molded, a part of which tightly fits into a concave or convex part formed on the shaft side. Therefore, there is no need to fill the connecting portion of the shaft with another resin or the like as in the conventional case, and manufacturing becomes easier. Furthermore, even if the ring magnet rotates at high speed, stress is less likely to concentrate on the retaining portion, and the inner cylinder portion is less likely to be destroyed.

Furthermore, positioning of the shaft and the inner cylinder part becomes more accurate due to the retaining part formed at the same time as the shaft and the inner cylinder part are integrated.

In addition, since at least the outer surface of the outer cylinder is made of resin mixed with magnetic material, the individual magnetic components are bonded to each other by the resin component, improving various properties such as vibration resistance, heat resistance, and impact resistance. do. For this reason,
Cracks etc. are less likely to occur, and molding of this part becomes easier.

Furthermore, even if the heat from the internal combustion engine is transferred to the ring magnet via the shaft, the inner and outer cylinders are cooled by the intermediate fins, so the resin molding that contains magnetic material, especially in the outer cylinder, Deterioration due to heat is prevented.

[Example] Hereinafter, a preferred example will be described based on the drawings.

FIG. 1 is a top view of a rotation angle sensor for an internal combustion engine, and FIG. 2 is a longitudinal sectional view thereof. In FIG. 2, numeral 1 is a shaft, 2 is a ring magnet integrally molded around the shaft 1, and 3 is a ring magnet integrally molded around the shaft 1.
is a retaining part consisting of a convex part formed integrally with the ring magnet 2 and protruding radially inward, and a concave part formed in the shaft 1 and recessed in the axial direction to fit the convex part. be. However, the unevenness relationship can also be reversed. Shaft 1 and ring magnet 2
are rotatably supported within the housing 4 in an integrated state.

The ring magnet 2 has an inner cylinder part 2a and an outer cylinder part 2c formed concentrically outside the inner cylinder part 2a, and a plurality of fins 2b connecting the two are formed radially (see Fig. 4). ).

As shown in FIG. 2, each fin 2b is parallel to the axial direction of the shaft 1 and is connected to the ring magnet 2.
It is formed into a single wall shape having a length comparable to the axial width of the outer cylinder portion 2c.

Further, the intervals between adjacent fins 2b in the circumferential direction of the ring magnet 2 are equal, and a large space is formed in a portion surrounded by a pair of adjacent fins 2b, an inner cylinder 2a, and an outer cylinder 2c.

Further, the shaft 1 is connected to an internal combustion engine (not shown) at one end (coupling 14, which will be described later).

This ring magnet 2 is integrally molded from a resin material (hereinafter referred to as magnetic resin) made by mixing magnetic powder into resin, and is magnetized at a predetermined position on the outer surface of the outer cylinder portion 2c. It is.

In this way, when magnetic resin is used, the resin component adheres the magnetic powder to each other, so the properties such as vibration resistance, heat resistance, and shock resistance are improved compared to when the ring magnet 2 is sintered with ferrite. I can do it. However, the fins 2b and the inner cylindrical portion 2a may be formed separately from an appropriate metal material or the like.

In addition, since the ring magnet 2 is integrally inserted with the shaft 1, the inner cylinder part 2a is integrated around the shaft 1 during molding, and is inserted into the connecting part between the inner cylinder part 2a and the shaft 1 at the same time as molding. A retaining portion 3 is formed, and in this retaining portion 3, a part of the inner cylindrical portion 2a is tightly fitted into the recess of the shaft 1, and the inner cylindrical portion 2a is prevented from coming off in the longitudinal direction of the shaft 1. Rotation is prevented in the circumferential direction.

Therefore, the inner cylindrical portion 2a and the shaft 1 are strongly connected, and even if the ring magnet 2 rotates at high speed, stress is difficult to concentrate on the retaining portion 3, and the inner cylindrical portion 2a
becomes less likely to be damaged. Further, the inner cylinder portion 2a and the shaft 1 are accurately positioned.

Furthermore, it is possible to eliminate the need to fill the space between the inner cylinder portion 2a and the shaft 1 with another resin after molding the ring magnet 2, and the manufacturing process becomes easier.

Moreover, the heat from the internal combustion engine is transferred to the shaft 1.
When the heat is transferred to the ring magnet 2 through the ring magnet 2, the heat is efficiently radiated into the space at the fins 2b while being transferred from the inner cylinder portion 2a to the outer cylinder 2c via the fins 2b. Furthermore, by forming a large space between adjacent fins 2b, the contact area between the fins 2b and the inner cylinder portion 2a and outer cylinder 2c can be increased. Also adjacent fin 2b
Air convection within the relatively large space between the two becomes active. Therefore, the cooling efficiency of the ring magnet 2 is improved, and cooling of the ring magnet 2 as a whole is promoted.

In particular, in the outer cylinder 2c, the durability of the ring magnet 2 can be improved by preventing thermal deterioration of the magnetic resin.

Furthermore, since the entire ring magnet 2 is molded from the same magnetic resin, fewer types of molding materials are required, which is advantageous in terms of molding. However, the outer cylinder part 2c
A magnetic resin is provided only on the outer surface of the inner cylinder part 2a,
By using other materials for the inner surfaces of the fins 2b and the outer cylinder portion 2c, the amount of expensive magnetic resin used can be reduced.

The housing 4 has a bottomed shape with an open top, and the shaft 1 passed through the bottom extends upward into the housing. Inside the open end of the housing 4, a bearing holder 5 is attached with a screw 6.
It is fixed by. A bearing 7 is fixed to the bearing holder 5 by a set plate 8 with a screw 9, and the upper end of the shaft 1 is supported by the bearing 7.

A boss portion is provided at the bottom of the housing 4 to protrude downward, and reference numeral 10 denotes a seal provided inside the boss portion.
11 is an O-ring, 12 is a spring ring, 1
3 is a connecting pin, and 14 is a coupling ring. A coupling ring 14 transmits rotation of a crankshaft of an internal combustion engine (not shown) to the shaft 1.

A support member 15 is attached to the inner wall of the housing 4 with screws 16. A screw hole for the screw 16 of the support member 15 is formed as an elongated hole.
A boss 17 is formed on the support member 15, and a sensor unit 18 is screwed onto the boss 17, and is disposed close to the outer cylindrical portion 2c.

On the other hand, the support member 15 and the portion of the housing 4 that comes into contact with the support member 15 are provided with concave and convex portions that engage with each other in the radial direction of the ring magnet 2. The sensor unit 18 is made slidable, and the position of the sensor unit 18 can be adjusted. This makes it easy to adjust the output level and timing of the sensor unit 18.

The sensor unit 18 includes Hall elements 18a, 18
18c, transistors, etc., and outputs a predetermined pulse signal when the magnetized portion of the outer cylinder portion 2c passes close to the magnetized portion. In this embodiment, the Hall element 18a generates 24 pulses per rotation of the ring magnet 2, and 1 rotation per rotation of the ring magnet 2.
8b is set to emit 4 pulses, and 18c is set to emit 1 pulse. However, the number and spacing of the magnetized parts formed on the outer surface of the ring magnet 2 can be set arbitrarily.

A groove is provided on the outer periphery of the open end of the housing 4, into which a seal rubber 19 is fitted, and a lid 20 is placed over the housing 4.
The housing 4 is fixed around the mating part of the lid part 20 with screws 21, and the housing 4 is hermetically sealed.

As shown in FIG. 1, a coupler 23 is provided at the tip of the signal cord 22 extending from the housing 4.
is provided with a mounting plate 23a, and a boss 24 (second
(see figure) can be attached from above using screws 25. That is, the direction in which the coupler 23 is screwed to the housing 4, and the direction in which the cover 2 is screwed to the housing 4.
0 is screwed in the same direction, so both can be attached at the same time from the same direction.
Therefore, when assembling the rotation angle sensor,
The three-axis automatic machine allows automatic assembly of the screws 21 and 25 from the same direction in one process, which reduces the manufacturing process.

Incidentally, reference numeral 26 (see FIG. 1) is a support plate for attaching the housing 4 to the engine, and is integrally attached to the bottom rear surface of the housing 4.

FIG. 3 shows the inside excluding the lid part 20. A grommet 28 is fitted into a through hole 27 provided on the side surface of the housing 4, and a signal cord 22 from the sensor unit 18 is extended to the outside of the housing 4 through the grommet 28.

As shown in FIG. 5, a groove 30 is provided horizontally on the mounting surface side of the support plate 26.
A groove 31 is provided in a direction perpendicular to a predetermined position, and a groove 32 is formed to communicate with the housing 4 in a vertical direction from the groove 31. These grooves 30,
Reference numerals 31 and 32 are formed as a labyrinth of air vent holes. That is, if the inside of the housing 4 is hermetically sealed by each seal, the internal pressure will increase due to the internal temperature rise, and the sensor unit 1
8 Hall elements 18a, 18b, 18c, etc. Therefore, the temperature rise is prevented by venting the air inside while maintaining waterproofness using the labyrinth-structured air vent holes made up of grooves 30, 31, and 32.

In the internal combustion engine rotation angle sensor configured in this way, when the ring magnet 2 rotates, the Hall elements 18a to 18c in the sensor unit 18 detect the magnetized portion of the outer surface of the ring magnet 2, and the signal pulse is detected. For example, the rotation angle of a crank of an internal combustion engine (not shown) is measured.

[Effects of the invention] The ring magnet of the invention integrally includes an inner cylinder part, fins, and an outer cylinder part, and the inner cylinder part is integrated with the shaft during molding, and at the same time, the retaining part is attached to the inner cylinder part and the shaft. formed at the connection part.

Therefore, it is possible to save the effort of filling the space between the shaft and the inner cylinder with another resin after molding, and the manufacturing is easy.

In addition, the inner cylinder part and the shaft are strongly connected, making it difficult for stress to concentrate on the retaining part, so even if a large force is applied to the joint between the shaft and the inner cylinder part due to high-speed rotation, the inner cylinder part will not be damaged. It can be made difficult. Furthermore, the inner cylinder part and the shaft can be accurately positioned by the retaining part.

Furthermore, even if the heat from the internal combustion engine is transferred to the ring magnet via the shaft, the inner and outer cylinders are efficiently cooled by the intermediate fins, so the magnetic material provided in the outer cylinder is Deterioration of resin due to heat can be prevented.

Furthermore, by providing magnetic resin on at least the surface of the outer cylinder, the vibration resistance, heat resistance, and impact resistance of the magnetic part are improved, preventing deformation such as cracking, and making molding easier. Improves durability.

[Brief explanation of the drawing]

Figures 1 to 5 show one embodiment; Figure 1 is a plan view of the external appearance, Figure 2 is a cross-sectional view taken along the line - - in Figure 1, and Figure 3 is a view with the lid removed. FIG. 4 is a plan view with bearings etc. removed, and FIG. 5 is a bottom view. Explanation of symbols, 1...Shaft, 2...Ring magnet, 2a...Inner cylinder, 2b...Fin, 2c
... Outer cylinder, 4 ... Housing, 5, 15 ... Supporting member, 7 ... Bearing, 10 ... Oil seal, 18 ... Sensor unit.

Claims (1)

[Scope of utility model registration request] A shaft with one end connected to an internal combustion engine, a cylindrical ring magnet that rotates together with the shaft and has a partially magnetized outer surface, and a ring magnet for detecting the rotation angle of the ring magnet. In the rotation angle sensor for an internal combustion engine, the sensor unit is disposed in close proximity to the outer surface of the shaft. It includes a plurality of fins extending radially outward in the direction and an outer cylinder part connected to the inner cylinder part through the fins, and the inner cylinder part, the fins, and the outer cylinder part are integrally formed. , at least the outer surface of the outer cylinder part is made of resin mixed with magnetic material,
Furthermore, the inner cylinder part is molded around the shaft and integrated with the shaft, and the part where the inner cylinder part and the shaft connect has a concave or convex part that was partially formed on the shaft side when the inner cylinder part was molded. A rotation angle sensor for an internal combustion engine, characterized in that a retaining portion is formed by fitting with the rotation angle sensor.