JP2008175680A - Wheel speed sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively manufacture a pair of wheel speed sensors P<SB>1</SB>, P<SB>2</SB>for right and left wheels. <P>SOLUTION: In the pair of wheel speed sensors P<SB>1</SB>, P<SB>2</SB>, each normal/reverse rotation direction and each rotational frequency of both objects to be detected are detected respectively by the same rotation detecting element 11 by magnetic field fluctuation caused by rotation of each object B, B rotating together with right and left wheels of a vehicle. In both rotation detecting elements 11 of the pair of wheel speed sensors, each detection rotation direction is reversed by reversing each surface facing to each object B. Since only reversing is required, the pair of wheel speed sensors for the right and left wheels can be acquired by each rotation detecting element having the same constitution, to thereby reduce manufacturing cost. Each detection sensitivity of both wheel speed sensors is equalized by equalizing each thickness of coating resins 11b, 4 from the center of the rotation detecting elements 11a to the wheel speed sensor surface on the facing side to the detection object. Hereby, handling on a wheel speed sensor design is facilitated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wheel speed sensor that detects forward and reverse rotation directions and rotation speeds of left and right wheels of a vehicle, and a manufacturing method thereof.

In this type of wheel speed sensor, the detection part is mounted (provided) on a resin holder (bobbin), the holder is inserted into the covered cylindrical casing from the opening, and the detection part is mounted. A pair of relay terminals are connected to the lead pieces of the lead, and the relay terminals are led out from the end surface of the holder base and connected to the output cable, and the relay terminal and the output are extended over the entire circumference of the casing opening and the holder exposed portion. In this configuration, a part of the cable is embedded and covered with resin (see Patent Document 1).
JP 2002-257840 A

  The detection unit includes a rotation detector (Hall IC) or the like in which a magnetic detection IC chip including detection circuits such as a rotation detection element, its power supply circuit, a signal processing circuit, and an output circuit is covered with a resin (Patent Document 1). 4), a pole piece is provided inside the bobbin for winding and holding the coil, and a magnet is provided on the rear side of the pole piece (electromagnetic pickup type patent document 1 see FIG. 1). The

Further, as shown in FIG. 4, the detection unit a composed of the former rotation detector or the like is not mounted on the casing, and the output cable 6 is directly connected to the lead piece without using a relay terminal. In some cases, the output cable 6 and the mounting bracket 10 are partially covered with the resin 4 (Patent Document 2).
JP 2003-57259 A

  As shown in FIG. 6A, the wheel speed sensor P includes an assembly of the detection part a (“detection part assembly” step in FIG. 6) and a processing / assembly of the output cable 6 (“cable part processing / assembly”). After the process is performed in a separate process, the detection part a and the output cable 6 are connected (same "detection part / cable part connection" process), and further coated with the resin 4 ("resin molding ( Wheel speed sensor formation) ”process), dimensional inspection, and whether normal rotation detection output is performed (the“ electrical inspection (output inspection) ”process) is shipped.

  As shown in FIG. 4, these wheel speed sensors P are provided facing the rotating detection target B, and the magnetic field fluctuation due to the rotation of the detection target B is detected by the detection unit a and converted into an electric signal. The signal is transmitted to an external control device via the relay terminal, the output cable 6 and the like. The detected body B has a ferromagnetic pulsar ring provided with gear-like teeth at the peripheral edge, or a magnet magnetized so that S and N poles appear alternately and continuously on the peripheral surface. Pulsar ring is used.

In this type of wheel speed sensor P, a rotation detector in which a pair of rotation detection elements (a Hall element, a magnetoresistive element (MRE), etc.) are provided in parallel in the rotation direction of the detection object B is employed in the detection part a ( As shown in FIGS. 3B and 11B) and FIG. 5, an output waveform formed based on signals from the pair of rotation detection elements due to magnetic field fluctuations based on the rotation of the detection object B (see FIG. 3B). Pulses) W ₁ and W ₂ are made different (for example, pulse widths are different) when the detection object B is rotated forward (FIG. (A)) and reverse (FIG. (B)). In some cases, the rotation direction of the detection object B is detected and the rotation number is detected based on the number of detected pulses (see Patent Document 3).
By detecting the direction of rotation, for example, it is possible to detect vehicle reverse in a slope start assist system that applies a brake when the vehicle reverses.
Japanese Patent Laid-Open No. 10-332725

For example, when the wheel speed sensor P that can detect the rotation direction and the number of rotations is used as a wheel speed detection sensor of an ABS (anti-lock / brake system) of the vehicle, the wheel speed sensor P is used for the front, rear, left and right wheels of the vehicle. Each is installed and connected to a controller, and each wheel speed sensor P detects the rotational direction and rotational speed of the front, rear, left and right wheels (see FIG. 1, in which the arrow direction is the front of the vehicle).
At this time, the rotation detection directions of the left and right wheel speed sensors P are reversed in a state of facing the detection object B (in FIG. 1, when the forward rotation is assumed to be normal rotation, the left wheel rotates forward clockwise). The right wheel is counterclockwise counterclockwise). For this reason, two types of wheel speed sensors P having different detection directions (detection rotation directions) of the rotation direction are required.

In this case, without changing the detection circuit in which the pair of rotation detection elements are incorporated, and without changing the connection mode with the detection circuit, the pair of rotation detection elements in the detection unit a of each wheel speed sensor P is changed to the left and right. If reversed, the detected rotation direction is reversed. For this reason, the direction of the detected forward / reverse rotation direction is set in each wheel speed sensor P by reversing the positions of the pair of rotation detection elements, and the right wheel wheel speed sensor P or the left wheel wheel. There is a speed sensor P.
Further, the wheel speed sensor P incorporates a rotation detection direction switching circuit, and as shown in FIG. 6B, between the “resin molding step” and the “dimension inspection” in FIG. “Setting (external electric signal application) step” is added, and in that step, a wheel speed sensor P for the right wheel or for the left wheel is inputted from the outside by inputting a switching signal of the detected forward / reverse rotation direction to the wheel speed sensor P. There is also means for providing a wheel speed sensor P.

Making the pair of rotation detecting elements forward and reverse to form a pair of wheel speed sensors for detecting the forward and reverse rotational directions and rotational speeds of the left and right wheels, two types of rotation with both rotational detection elements being forward and reverse It is necessary to make a detector, which leads to cost increase.
Further, the means for switching by transmitting a switching signal of the detected forward / reverse rotation direction from the outside to each wheel speed sensor P needs to add a switching circuit in the detection part a (rotation detector) and Equipment for the “setting process” is required, which is also a cause of cost increase.

  This invention makes it a subject to make it possible to manufacture at low cost two types of wheel speed sensors having different detection rotation directions, such as the pair of wheel speed sensors for the left and right wheels as described above.

In order to achieve the above object, the present invention provides a rotation detector or the like provided with a rotation detection element such as the Hall element or magnetoresistive element in a pair, and the surface facing the detection target B is reversed. Paying attention to the fact that the detected rotation direction is forward and reverse, both the rotation detectors of the pair of wheel speed sensors for the left and right wheels of the vehicle are such that the surfaces facing the detected body B are reversed. It was.
In this way, two types of wheel speed sensors having different detection rotation directions such as for left and right wheels are obtained with a rotation detector having the same configuration (for example, the same detection circuit incorporating a pair of rotation detection elements). be able to.

  As a configuration of the present invention, in the wheel speed sensor for detecting the rotation direction and the rotation speed of the detected object by the rotation detector by the magnetic field fluctuation caused by the rotation of the detected object, the rotation detector of the wheel speed sensor is provided. As the same configuration, two types of wheel speed sensors having different detection rotation directions are obtained by adopting the opposite surfaces of the surface to be detected.

  The two types of wheel speed sensors having different detected rotation directions may be a pair of wheel speed sensors that detect the rotation direction and the rotation speed of the left and right wheels of the vehicle. That is, in a pair of wheel speed sensors for detecting the forward and reverse rotation directions and the rotational speeds of both detected bodies by means of a rotation detector due to the magnetic field fluctuation caused by the rotation of the detected bodies rotating with the left and right wheels of the vehicle, The both rotation detectors of the pair of wheel speed sensors may have the same configuration, and the surfaces facing the detected object may be reversed.

Here, the detection sensitivity of the wheel speed sensor is based on the surface of the wheel speed sensor facing the object to be detected, and rotation when the object to be detected is opposed by a specific distance from the reference (surface). It is determined by the magnitude of the output of the detection element. When the wheel speed sensor is attached to the wheel portion, the wheel speed sensor is attached to the object to be detected at a distance from the detection surface (reference surface) that can obtain the required detection sensitivity.
For this reason, it is preferable that the detection sensitivity of the two types of wheel speed sensors having different detection rotation directions, such as for left and right wheels of the vehicle, is the same. This is because if the detection sensitivities of the two types of wheel speed sensors are different, the mounting manner of the two wheel speed sensors, for example, the distance from the detected object is different, and the mounting work becomes complicated. Incidentally, the detection sensitivity of the two types of wheel speed sensors need not be the same unless the complexity is taken into consideration.

Here, the detection sensitivity of the rotation detection element is based on the center of the rotation detection element (see c in FIG. 3A) or the surface, and the output of the rotation detection element at a point away from the reference by a specific distance. Even if the rotation detecting element is resin-coated, it is not affected by the resin thickness.
On the other hand, the detection sensitivity of a rotation detector in which the rotation detection element is coated with a resin is determined by the magnitude of the output of the rotation detection element at a point separated from the reference by a specific distance with respect to the surface of the coating resin. For this reason, the thickness of the coating resin affects the detection sensitivity of the rotation detector. Further, as described above, the detection sensitivity of the wheel speed sensor is based on the surface of the wheel speed sensor facing the object to be detected, and the magnitude of the output of the rotation detection element at a point away from the reference by a specific distance. Therefore, similarly, the thickness of the coating resin of the rotation detection element and the thickness of the protective resin of the rotation detector influence the detection sensitivity of the wheel speed sensor.

From these, as means for making the detection sensitivities of the two types of wheel speed sensors different in the detection rotation direction, in the two types of wheel speed sensors such as the above-described rotation detector protected by resin, The thicknesses of the protective resins on the sides of the two rotation detectors facing the object to be detected are set so that the detection sensitivities of the two wheel speed sensors are the same.
In this way, if the detection sensitivity of the rotation detector when the surface of the rotation detector facing the object to be detected is reversed, the detection speed of the wheel speed sensor at the design stage of the wheel speed sensor is different. The thickness of the protective resin is set appropriately so that the detection sensitivity on the front and back sides is the same. For example, the thickness of the protective resin when using the front side: how many mm, the thickness of the protective resin when using the back side : How many mm is set, and in the “resin molding process” of FIG. 6A, the detection sensitivity of both wheel speed sensors is made the same by molding the protective resin on the front and back of the rotation detector with the set thickness. Can be.

  Further, as described above, the detection sensitivity of the mounted wheel speed sensor is measured (set) at a constant distance (a constant gap from the detection object B) from the surface of the protective resin. Making the detection sensitivity the same by setting the thicknesses of both protective resins on the front and back sides makes it easy to obtain the required detection sensitivity when the wheel speed sensor is attached. This is because the required detection sensitivity can be set by setting the distance (gap) between the surface of the protective resin and the detection object B.

Further, if the both rotation detectors are each formed by coating a rotation detection element such as the Hall element or magnetoresistive element with a resin, the surface of the coated resin facing the object to be detected from the rotation detection element. It is preferable to make the thickness of the coating resin up to the back surface the same.
In the two types of wheel speed sensors in which the surface of the rotation detector facing the object to be detected is reversed, when the detection sensitivities of the two wheel speed sensors are different, the detection sensitivity is different from the rotation detection element. Since the thickness of the coating resin facing the detection body is different from the front and back surfaces, if the thickness of the coating resin on the front and back surfaces of the rotation detection element is the same, detection of the rotation detector on the front and back surfaces of the rotation detector The sensitivity will be the same. This means that in the manufacturing stage (design stage) of the rotation detector, the thickness of the coating resin of the rotation detecting element is the same on the front and back surfaces.
If the detection sensitivity on the front and back surfaces of the rotation detector (detection sensitivity of the rotation detector) is the same, the thickness of the protective resin on the front and back surfaces is the same, so that the rotation detector is reversed 2 The detection sensitivity of each type of wheel speed sensor is the same.

From the above, in order to make the detection sensitivities of two types of wheel speed sensors having the same rotation detector of the same configuration upside down, the respective coating resins on the side facing the detection object from the center of the rotation detection element The distance to the surface (the surface of the rotation detector covering resin) should be the same.
By the way, in the rotation detector with the rotation detection element coated with resin, the detection sensitivity on the front and back surfaces of the rotation detection element is the same, for example, by making the both thicknesses of the front and back sides of the rotation detection element of the protective coating resin the same. Then, in the case of making two types of wheel speed sensors having the same rotation detector and different detection rotation directions, the rotation detector can be obtained as long as the protective cover of the rotation detector has the same thickness. Since the detection sensitivities of the various wheel speed sensors can be made the same, it is advantageous in the manufacture thereof.

  With the rotation detectors, the forward and reverse rotations of the left and right wheels of the vehicle can be performed by using the rotation detectors to determine the forward and reverse rotation directions and the rotational speeds of the detected bodies. As one means for manufacturing a pair of wheel speed sensors for detecting the direction and the number of rotations, both rotation detectors for detecting the forward and reverse rotation directions and the number of rotations of the left and right wheels of the vehicle have the same configuration, A surface of the both rotation detectors facing the detection object is turned upside down, and a pair of wheel speed sensors for detecting forward and reverse rotation directions and rotation speeds of the left and right wheels of the vehicle are used.

  At this time, not only the pair of wheel speed sensors for the left and right wheels of the vehicle, but also when manufacturing two types of wheel speed sensors having different detection directions of the rotation direction, the both rotation detectors of the two types of wheel speed sensors are: In addition, it is assumed that the surface facing the object to be detected is of the same configuration, and that the surface opposite to the surface is reversed, and from the center of the rotation detection element to the surface facing the object to be detected of the resin whose protective detector is coated If the distances are the same, the detection sensitivities of the two types of wheel speed sensors can be made the same.

  In these manufacturing methods, the thickness of the protective resin on the side of the both-rotation detector facing the object to be detected is set so that the detection sensitivities of both wheel speed sensors are the same, The distance from the center of the detection element to the surface of the protective coating resin on the side facing the object to be detected is the same, or each protective coating resin on the side facing the detection object of both rotation detectors The detection sensitivity of both wheel speed sensors can be made the same by making the thickness the same, or making both the thicknesses of the coating resin from the rotation detection element to the front and back surfaces of the coating resin facing the object to be detected the same. Of course.

According to the present invention, two types of wheel speed sensors having different detection rotation directions, for example, a pair of wheel speed sensors for left and right wheels can be obtained with the rotation detector having the same configuration, so that the manufacturing cost can be reduced. Can be achieved.
If the detection sensitivity of the two types of wheel speed sensors becomes the same by adjusting the thickness of the protective resin of the rotation detector, setting the thickness of the coating resin of the rotation detection element, etc., Since the gap setting of each wheel speed sensor (detection unit) can be made common to the left and right, handling in vehicle design becomes easy. Furthermore, when the detection sensitivity of the two types of wheel speed sensors is made the same by setting the thickness of the coating resin of the latter rotation detection element, it is not necessary to set the thickness of the protective resin of the former rotation detector. Therefore, in the design of the wheel speed sensor, it is easy to handle the design, for example, by setting the thickness of the protective resin to be the same.

1 to 3 show an embodiment of the present invention. As shown in FIG. 1, this embodiment has a left and right front and rear of each detected object B that rotates together with front and rear left and right wheels of an automobile (vehicle). A pair of wheel speed sensors P ₁ and P ₂ (generic symbol: P) is provided. In the figure, D is a mounting member on the vehicle side.
The wheel speed sensor P does not mount the detection unit a including the rotation detector 11 and the like on the casing, and directly connects the output cable 6 to the lead piece 12 without using a relay terminal. 6 and a part of the mounting bracket 10 are covered with the resin 4.

This wheel speed sensor P is manufactured by the process shown in FIG. At this time, the protective resin 4 of the detection part a is set uniformly on all the wheel speed sensors P on the surface facing the detection object B (the lower surface in FIG. 2) (thickness from the surface of the rotation detector 11). t is set the same).
Corresponding to the distinction between the left wheel and the right wheel, for example, the case where the front side of the following rotation detector 11 faces the detected body B is for the left wheel and the back side of the rotation detector 11 is the detected body B. When the protective resin 4 is provided, the front and back of the rotation detector 11 are appropriately set so that the right wheel is used for the right wheel.
Further, on the surface of the protective resin 4, if the display is for the left and right wheels, for example, the left front wheel is indicated by a chain arrow or the like as in the wheel speed sensor P1 for the left front wheel in FIG. Good.

As shown in FIG. 3, the rotation detector 11 has a pair of Hall elements 11a and 11a arranged, and both Hall elements 11a and 11a are provided with detection circuits (not shown) such as a power supply circuit, a signal processing circuit, and an output circuit. They are connected and covered with a resin 11b. As shown in FIG. 5A, the thicknesses b1 and b2 of the upper and lower coating resins 11b from the center line c of the Hall element 11a are the same (b1 = b2). Is set.
For this reason, the detection sensitivity of the rotation detector 11 is the same regardless of which of the front and back surfaces (upper and lower surfaces in FIG. 3A) is opposed to the detection object B.

As shown in FIG. 1, each wheel speed sensor P has, for example, a left wheel for which the surface of the rotation detector 11 is opposed to the detected body B and a back surface of the rotation detector 11 for the detected body B. The opposite one is for the right wheel, and the pair is installed on the front and rear wheels, respectively. At this time, the detection circuit incorporating the pair of rotation detection elements 11a and 11a forming the rotation detector 11 of each wheel speed sensor P is the same, and each of the rotation detectors 11 has the same configuration.
If installed in this way, the output waveform of the rotation detector 11 due to the magnetic field fluctuation based on the rotation of the detection object B is reversed from the normal rotation of the detection object B (FIG. 5A) as in the conventional case. (W ₁ and W ₂ ) are output differently at the time ((b) in the figure), and the controller C to which the output is input calculates the rotation speed and rotation direction of each detected object B. It detects the vehicle's forward / backward travel and its speed.

In the rotation detector 11 of this embodiment, the thicknesses b1 and b2 of the upper and lower coating resins 11b from the center line c of the hall element 11a are the same (b1 = b2). The thickness of the protective resin 4 of the part a (thickness t of the protective resin 4 in FIG. 2A) is not made uniform on all the wheel speed sensors P on the surface facing the detected body B, and the rotation detector 11 is used. In both cases, the thickness t of the protective resin 4 is appropriately set so that the detection sensitivity of the same wheel speed sensor P is obtained.
Further, instead of the Hall element 11a, other known rotation detecting elements such as a magnetoresistive element can be employed.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the above-described meaning. For example, the scope of the present invention is not limited to the pair of left and right wheel speed sensors P ₁ and P ₂ , but relates to two types of wheel speed sensors having different detection rotational directions. , And is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Schematic attachment mode diagram to vehicle of one embodiment Enlarged view of the main part A part of rotation detector of the embodiment is shown, (a) is a cut front view, (b) is a perspective view. FIG. 2 is a schematic view of the mounting of a wheel speed sensor, where (a) is a left side view and (b) is a front view. Output waveform diagram of the wheel speed sensor Manufacturing process diagram of wheel speed sensor

Explanation of symbols

4 Protective resin 6 Output cable 10 Mounting bracket 11 Rotation detector (Hall IC)
11a Hall element (rotation detection element)
11b Rotation detector coating resin 12 Lead piece a Detectors b1, b2 Coating resin thickness c Hall element 11a center line t Protective resin thickness P, P ₁ , P ₂ Wheel speed sensor B Detected object C Controller D Mounting member on the vehicle side

Claims (6)

With the rotation detectors (11, 11), the rotation direction of the detected bodies (B) and the number of rotations of the detected bodies (B) are changed by the magnetic field fluctuation caused by the rotation of the detected bodies (B, B) rotating together with the left and right wheels of the vehicle. In each pair of wheel speed sensors (P ₁ , P ₂ ) to be detected,
Both rotation detectors (11, 11) of the pair of wheel speed sensors (P ₁ , P ₂ ) have the same configuration, and the surfaces facing the detected bodies (B, B) are reversed. A wheel speed sensor characterized by The pair of wheel speed sensors (P ₁ , P ₂ ) according to claim 1, wherein the both rotation detectors (11, 11) are covered with a resin (4). The thickness (t) of each of the protective resins (4) on the side facing the detected body (B, B) is set so that the detection sensitivity of both wheel speed sensors (P ₁ , P ₂ ) is the same. Wheel speed sensor characterized by being set to The both rotation detectors (11, 11) are obtained by coating the rotation detection elements (11a, 11a) with resins (11b, 11b), respectively, and the detected object from the center of the both rotation detection elements (11a). (B, B) The distance (t + b1, t + b2) to the surface of the protective coating resin (4) on each side facing (B, B) is the same, and the detection sensitivity of both wheel speed sensors (P ₁ , P ₂ ) is the same The wheel speed sensor according to claim 2, wherein   The thickness (t) of the protective coating resin (4) on both sides of the both rotation detectors (11, 11) facing the detection target (B, B) is made the same, and the rotation detection is performed. Both thicknesses (b1, b2) of the coating resin (11b) from the element (11a) to the front and back surfaces of the coating resin (11b) facing the detected body (B) are the same. Item 4. The wheel speed sensor according to item 3. Rotation detectors (11, 11) determine the forward and reverse rotation directions and the rotational speeds of the detected bodies (B, B) due to magnetic field fluctuations caused by the rotation of the detected bodies (B, B) rotating with the left and right wheels of the vehicle. Therefore, in the method of manufacturing a pair of wheel speed sensors (P ₁ , P ₂ ) for detecting forward and reverse rotation directions and rotation speeds of the left and right wheels of the vehicle,
Both rotation detectors (11, 11) for detecting forward and reverse rotation directions and rotation speeds of the left and right wheels of the vehicle have the same configuration, and the detected object (B) of both rotation detectors (11, 11) , B) A method of manufacturing a pair of wheel speed sensors (P ₁ , P ₂ ) that detects the forward and reverse rotational directions and the rotational speeds of the left and right wheels of the vehicle, with the surface facing B) reversed. The rotation detector (11) is covered with a resin (4), and the rotation direction and the number of rotations of the detection object (B) are determined by the magnetic field fluctuation caused by the rotation of the detection objects (B, B). ) In the manufacturing method of each wheel speed sensor (P) to be detected by
Upon detecting the direction of the rotational direction to produce two different said wheel speed sensors _(P 1, _{P 2),} the two wheel speed sensors _(P 1, _{P 2)} of both rotary detector (11, 11 ) Are of the same configuration, the surfaces facing the detected bodies (B, B) are reversed, and the detected bodies of the both rotation detectors (11, 11) The thickness (t) of each of the protective resins (4) on the side facing (B, B) is set so that the detection sensitivities of the two types of wheel speed sensors (P) are the same. A manufacturing method of the wheel speed sensor (P).

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