KR20100112927A - Tension sensing device of the epb - Google Patents

Abstract

PURPOSE: An electronic parking brake tension sensing device. The job load except for tension is excluded. The exact sensing of the brake wire accomplishes. CONSTITUTION: The electronic parking brake tension sensing device. The HOOKER part(1), and the sensing body portion(2) and joint part(3) is included. In the HOOKER part, the brake wire is fixed. The sensing body portion is combined in the HOOKER part. The sensing body portion measures the tensile force of the brake wire through the diaphragm(22).

Description

Tension sensing device of the EPB

The present invention relates to a sensor device for measuring a tensile force mounted on an electronic parking brake system, and more particularly, to an electronic parking brake tension sensing device that can effectively eliminate the miscellaneous loads of moments, torsions and the like except for pure tensile force.

For electronic control of tension, it is necessary to accurately measure the tension of an object with an electric signal value, and in order to generate such an electric signal, a normal strain gage is attached to a member having a displacement value by tension, The detection signal of the strain gauge whose resistance value changes with the displacement of a member is used.

The electronic control of this tension is the electronic parking brake (EPB), which is a brake that is automatically locked when the car is standing, and is released automatically by stepping on the accelerator pedal when starting. These electronic parking brakes do not have to worry about the brakes being released in the middle of the vehicle even if the driver is not braking. When starting the vehicle, the brakes are automatically released when the user presses the pedal while the brakes are locked. In extreme cases, the driver's comfort is improved.

The electronic parking brake is configured to pull the brake wire through the brake operating motor by combining the driver's intention, such as information on the condition of the car, the inclination of the parking position, and the operating distance of the handle or the pedal.

That is, the braking force of the car is determined by the tension of the brake wire for activating the brake, and a tension measuring device for sensing the tension of the brake wire is used as a means for determining whether the brake wire is pulled with an appropriate tension by the brake operating motor. .

The tension measuring device detects the tension of the brake wire by a force sensor and transmits it to a control unit (EPB ECU, ECU, etc.) that controls the brake drive motor so that the tension of the brake wire can be properly controlled. do.

An example of such a tension measuring device is shown in FIG.

The tension measuring device is provided with the through holes 11a and 11b at both sides, the housings 10a and 10b having the space portion 12 formed therein, and are arranged in parallel with the through holes and fixed to the space portion. Torsion member 20 having a fastening hole 21 formed therein; an input shaft 30 to which one end is coupled to the fastening hole and the other end is exposed to the outside of the one through hole, and the wire 1 to which tension is transmitted is fixed; One side is connected to the conventional length adjusting means, the other side is the amount of the twisting member is deformed while pulling the input shaft by the force of the control shaft 40 and the control shaft is coupled to the opposite side through-hole through which the input shaft is projected. It includes a strain gauge (50) attached to one side of the fastening hole to measure.

Here, the conventional length adjusting means, the control shaft 40 is a brake wire drive motor made of a hydraulic cylinder or a linear guide using a motor that is connected to the outer end to adjust the tension of the wire pull or push. At this time, the operation of the length adjusting means is made by an electrical signal output through the strain gauge of the torsion member provided in the housing.

The torsion member 20 may increase the displacement due to the incision line 22, but the torsion member 20 and the housing when the tension is applied by the wire 1 because the incision line 22 is asymmetrically formed. (10a) (10b) there is a disadvantage that the stress is not distributed evenly, and thereby a bending moment and torsion occurs in the torsion member. This undesired miscellaneous load affects the strain gauge tension measurement, making it difficult to accurately measure the net tension of the wire.

Therefore, it is difficult to maintain a constant tension of the brake wire required by the design, thereby reducing the reliability of the accurate operation of the electronic parking brake.

In addition, fatigue accumulated in the torsion member and the housing due to the tension that changes frequently in the frequent use of the electronic parking brake causes a shortening of the life of the tension measuring device. In the conventional tension measuring device, appropriate countermeasures are taken into consideration. It was not.

The present invention has been made to solve the above-described problems, the embodiment of the present invention has the object of making accurate sensing of the brake wire by excluding the miscellaneous load except tension.

More specifically, the diaphragm is used to exclude miscellaneous loads.

In addition, the object of the present invention is to keep the stress distribution inside the housing of the sensing device as uniform as possible to minimize the occurrence of miscellaneous loads.

In addition, it has the purpose of delaying the damage caused by the fatigue load of the sensing device to increase the life of the sensing device.

On the other hand, there is also an object to facilitate the manufacture of the sensor device by expanding the attachable range of the sensor for measuring the tension.

In order to solve the above problems, the present invention is to measure the tensile force of the brake wire through the diaphragm attached to the hooker portion and the hooker portion fixed to the brake wire, the semiconductor strain gauge 23 is attached in an embodiment An electronic parking brake device coupled to the sensing body portion and the sensing body portion, the rear end includes a joint portion is fixed to the tension control shaft.

In addition, the rear of the joint portion has a rectangular appearance having a bottom surface and both sides forming a circumference, a rear end surface is formed at the rear end is formed with a fixing groove for locking the tension control shaft, the bottom surface inside the joint portion The present invention proposes an electronic parking brake tension sensing device, characterized in that the stress distribution hole is formed to be punched evenly.

In addition, a mounting head is formed at an end of the brake wire and the tension adjusting shaft, and each mounting head is secured to the locking groove formed in front of the hooker portion and the fixing groove, and each of the locking groove and the fixing groove is fixed. The outer edge proposes an electronic parking brake tension sensing device, characterized in that to form an inclined stress distribution surface for the relaxation of concentrated stress.

In addition, the front surface of the sensing body portion, the receiving protrusion which protrudes from the center and is coupled to the hooker portion, an annular notch groove is formed around the center, so that the linear rate of change of the diaphragm section between the notch groove and the receiving protrusion is increased. An electronic parking brake tension sensing device characterized in that the slope is formed.

In addition, the diaphragm proposes an electronic parking brake tension sensing device, characterized in that the disk projection having a center coinciding with the center of the receiving projection is further formed to increase the strain of the attachment surface to which the strain gauge is attached.

According to the electronic parking brake tension sensing device according to the embodiment of the present invention as described above, due to the optimum design of the diaphragm in the sensing body and the proper arrangement of the piezoresistive element, the compensation action of the Wheatstone bridge circuit, It is designed to exclude various miscellaneous loads such as moments, and it has the effect of enabling accurate operation of the electronic parking brake system. Also, the stress dissipation groove formed in the joint portion further improves the miscellaneous load removal characteristics. Has

In addition, when the stress distribution surface formed in the locking groove and the fixing groove is formed, it is possible to exclude the stress concentrated in the locking groove and the fixing groove has the effect of increasing the life by preventing this portion is broken by fatigue.

In addition, in the case where the sloped slope is formed on the sensing body, the area where the strain gauge can be attached is increased, thereby significantly reducing the incidence of defective products due to the mounting position error of the strain gauge, and alleviating the difficult attachment process due to the in-situ attachment. It has the effect of reducing the production cost.

In addition, when the disk protrusion is further formed, as the strain of the diaphragm is increased to enable more sensitive tension measurement, it is possible to operate the electronic parking brake system more accurately.

Hereinafter, the function, configuration and operation of the electronic parking brake tension sensing device of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view showing a state of use of the electronic parking brake tension sensing device according to an embodiment of the present invention, Figure 2 is an exploded perspective view of the electronic parking brake tension sensing device shown in FIG.

In the electronic parking brake tension sensing device 100 according to an embodiment of the present invention, the hooker part 1 to which the brake wire 4 is fixed and the hooker part 1 are coupled, and the semiconductor strain gauge 23 is connected to the hooker part 1. The joint part which is coupled to the sensing body part 2 for measuring the tension force of the brake wire 4 and the sensing body part 2 through the attached diaphragm 22, and the tension control shaft 5 is fixed at the rear end ( Include 3).

The brake wire 4 is coupled to the front end of the hooker 1, and the tension control shaft 5 is coupled to the rear end of the joint 3 placed on a straight line with the brake wire. The tension adjusting shaft 5 is connected to a known brake driving motor (not shown) and configured to adjust the tension of the brake wire 4 by being pulled or released, and the sensing body 2 has the brake wire 4. By measuring the tension of the brake drive motor is configured to be delivered to a separate control device for controlling.

A hooking groove 11 having an upper portion is formed in front of the hooker part 1, and the brake wire 4 is caught and fixed to the hooking groove 11. Preferably, the brake wire 4 is fixed to the locking member D in which the mounting head D1 is formed, and the mounting head D1 is inserted into the locking groove 11 and fixed. In addition, the rear side of the hook portion (1) is formed with a protrusion projection 12.

On the other hand, the sensing body portion 2 is coupled to the coupling protrusion 12 through the receiving protrusion 21 protruding in the front. Specifically, the center of the receiving protrusion 21 is formed with a groove that can accommodate the coupling protrusion 12, the coupling protrusion 12 inserted into the groove is firmly fixed through welding or the like.

At this time, the center of the receiving projection 21 of the sensing body portion 2 and the engaging projection 12 of the hooker portion 1 is to be coincident with the center of the brake wire 4 and the tension control shaft 5 located on a straight line. It is preferable to form so that the working point of the tension and the engagement position of the hooker and the sensing body portion does not shift and generate a moment.

In addition, the diaphragm 22 is formed in the rear inner side of the sensing body 2 by having a recessed circular flat plate. The strain gauge 23 is attached to this diaphragm 22, and the strain of the diaphragm is calculated through the strain gauge when the receiving projection 21 is pulled out.

In this case, a pair of strain gauges 23 are symmetrically attached so that the piezoresistive elements 231 are arranged on an imaginary straight line passing through the center of the diaphragm, and each strain gauge includes a pair of piezoresistive elements 231.

Therefore, four piezoresistive elements 231 are arranged in a line on the virtual straight line. That is, in the piezoresistive element 231, the first piezoresistive element and the third piezoresistive element are the same with respect to the center of the diaphragm 22. Located on the distance, the second piezoresistive element and the fourth piezoresistive element are also located on the same distance. The Wheatstone bridge as known from the piezoresistive element 231 having such an attachment position can be constituted, and the strain value can be measured from the following equation (1).

는 각 압저항소자의 변형률(ΔR/R)이다.Where V is the voltage, K is the proportionality (gauge factor),

Is the strain (ΔR / R) of each piezoresistive element.

At this time, the strain gauge 23 is a semiconductor strain gauge having a high gauge factor so as to increase the strength of the diaphragm.

The diaphragm 22 of the sensing body 2 has a result measured through a circuit board 24 electrically connected to a strain gauge, and a flexible printed circuit 241 or a substitute thereof coupled to the circuit board. It is configured to transmit to the outside.

In addition, the steel bar 25 supports and fixes the circuit board, and at the same time serves to ground the ground of the circuit board to the sensing body. In this way, when the sensor is completely assembled, the circuit board is completely trapped by the sensing body part and the joint part made of metal material, and the ground of the circuit board has the same potential as that of the sensing body part. do.

On the other hand, the front of the joint portion 3 is fixed to the sensing body portion 2, the rear is a rectangular appearance in which the bottom surface 31 and both sides 32 form a circumference, the rear end of the tension control shaft (5) ) Is formed with a rear end surface 33 having a fixing groove 334 is fixed.

At this time, the outer shape of the joint part has a rectangular shape in order to be placed in the electronic parking brake system (not shown), and may be formed in a polygon according to a design modification of the electronic parking brake system.

The front of the joint part 3 is formed with a groove for accommodating a circuit board and a steel bar mounted on the sensing body part 2. The sensing body portion 2 is fixed by welding its edge to a groove formed in front of the joint portion. At this time, the above-described flexible electronic circuit 241 is coupled to the connector 26, one end is coupled to the outer peripheral surface of the joint portion 3, the other end is coupled to the circuit board 241.

In addition, the rear part of the joint part 3 forms a space in which the upper part is opened by the rear end surface 33 on which the bottom surface 31, both side surfaces 32, and the fixing groove 334 are formed.

At this time, the mounting shaft (D1) is formed in the tension control shaft (5), or the engaging member (D) is formed in the mounting head is coupled to the mounting head is inserted into the space, the locking groove 334 is fixed.

3 is a perspective view partially cut in the joint part employed in the electronic parking brake tension sensing device shown in FIG. 1, and FIG. 4 is a cross-sectional view taken along line AA of FIG. 3.

When the tension by the brake wire 4 acts on the sensing device 100, the bottom surface of the joint part 3 (to avoid miscellaneous loads such as moments, torsions, etc.) caused by the asymmetry of the rear of the joint part is formed asymmetrically. 31, a stress distribution hole 311 is formed to even out the stress distribution inside the joint portion.

The stress at the back of the joint due to the tension of the brake wire is formed on both sides and bottom. If the stress dispersion holes are not formed, both sides are formed to be symmetrical with each other so that the stress does not concentrate more on any one side, but there is no ceiling surface corresponding to the floor, Are concentrated. As a result, a job load such as a bending moment is generated in the longitudinal direction of the joint part, and this job load affects the deformation of the diaphragm firmly fixed to the front of the joint part. The strain of the diaphragm is measured.

Although the Wheatstone bridge circuit formed by the diaphragm structure and the strain gauge is designed to primarily remove the influence of the miscellaneous load, the purpose of the stress distribution holes is to alleviate the cause of the moment.

When the stress distribution holes 311 are formed, as shown in FIG. 4, the area of the bottom surface 31 is reduced to further increase the magnitude of the stress distributed on both side surfaces 32. That is, as described above, the stress distributed on both sides becomes larger and the stress on the bottom is relatively smaller than the case where the stress dispersion hole is not formed, so that the magnitude of the miscellaneous load caused by the stress biased on the bottom is reduced. It can be made smaller. Therefore, it is possible to measure the tension more accurately by reducing the influence on the diaphragm by the miscellaneous load.

Meanwhile, FIG. 5 is a plan view of the electronic parking brake tension sensing device shown in FIG. 1, FIG. 6 is an enlarged view of a portion B of FIG. 5, (a) is a plan view showing before deformation, and (b) is deformation. It is a top view which shows the following.

In order to prevent the sensing device 100 which is continuously deformed by the changing tension of the brake wire from being damaged by fatigue load for a long time, the outer grooves of the engaging grooves 11 and the fixing grooves 334 are concentrated under stress. It is preferable that the inclined stress distribution surface Z is formed for relaxation.

Hereinafter, the working relationship of the stress distribution surface Z in the fixing groove 334 will be described, and this working relationship is equally applied to the locking groove 11.

As shown in (a) of FIG. 6, the cylindrical body D2 extending from the center of the mounting head D1 is inserted into the fixing groove 334 having an open top, whereby the cylindrical body D2 is In contact with the inner surface 334a of the fixing groove 334.

As exaggerated in FIG. 6B, when tension is applied by the brake wire 4 when the stress dispersion plane is not formed (indicated by the dotted lines), the outer edge P of the fixing groove is Deformed at an acute angle, the inner edge Q is deformed to form an obtuse angle. At this time, the stress is concentrated in the outer edge (P) of the fixed groove deformed at an acute angle, fatigue easily accumulates according to frequent changes in tension, and eventually leads to breakage.

Therefore, by chamfering the outer edge of the fixing groove 334 to form a stress dispersion surface (Z) there is no portion deformed at an acute angle even after deformation so that stress is not concentrated on the outer edge portion of the fixing groove 334.

In this case, since there is no concentration of large stress even in the deformation of a plurality of times, there is an effect that the breakage due to fatigue is prevented and the life is increased.

FIG. 7 is a cross-sectional view of the sensing body along the C-C line of FIG. 2.

In order to accurately measure the tension in a predetermined range added to the sensing device 100 through the strain gauge 23 attached to the diaphragm 22 formed in the sensing body portion 2, the strain gauge 23 is the diaphragm 22 It should be attached within the range that changes linearly due to medium tension.

The front surface of the sensing body portion 2, that is, the opposite surface of the diaphragm, is formed with a known annular notch groove 221 which increases the deformation of the diaphragm 22. On the front surface of the sensing body 2 extending from the notch groove 221 to the receiving protrusion 21, a non-inclined slope 222 is formed to increase the linear rate of change of the diaphragm 22.

Such sloped surface 222 is formed as an inclined straight line extending from the notch groove 221 to the outer surface of the receiving projection 21 when viewed in cross section, the diaphragm 22 when tension is applied to the diaphragm 22 By increasing the interval having a linear strain in the strain gauge 23 is to expand the space that can be attached.

In more detail, since the left and right of the diaphragm 22 is symmetrical in FIG. 7, it can be seen that the stress distribution along the cross section of the left or right side is symmetric with respect to the center to which the tension is applied. In addition, the deformation of the diaphragm 22 can be seen to be deformed by the force to be pulled back to the left and right edge portion in the center of the diaphragm. Therefore, the attachment position of either strain gauge 23 by the diaphragm 22 can be simplified to the end of a cantilever beam shown in FIG.

In FIG. 8, the conventional diaphragm is a cantilever beam having the same thickness as shown in (a), and when the shear stress (arrow direction) is applied to the end thereof, the cantilever curve is known as it occurs. Therefore, the linear strain section can be secured only in a very narrow section, making the strain gage attachment process very difficult.

On the other hand, the diaphragm 22 according to the present invention is a sloped surface 222 is formed, as shown in Figure 8 (b) is the same as the cantilever bottom surface formed as an inclined surface, when the same shear stress as described above, it is well known As shown, the cantilever becomes a straight deformation. Therefore, since the section where the strain gauge can be attached, that is, the section where the linear strain is obtained, becomes wider, the defective rate due to the wrong position of the strain gauge is significantly reduced.

This increase in the linear interval is clearly shown in the contrast plot showing the strain of the diaphragm, as shown in FIG.

In FIG. 9, the triangles correspond to a conventional diaphragm in which no slope is formed, and the squares correspond to a diaphragm having a slope. In this case, the horizontal axis represents the distance (L in FIG. 7) from the end of the disc protrusion, which will be described later, to the outermost portion of the diaphragm, that is, the entire section to which the strain gauge can be attached, and the vertical axis represents the strain.

According to the prior art without a slope, since a linear strain is present in a section of about 6.5 mm to 7.75 mm, a strain gauge having a length of about 1 mm should be attached to this section, but according to the present invention, up to 5.75 mm to 8.5 mm It can be seen that the linear strain in the wide interval of increases the attachable interval of the strain gauge.

On the other hand, the diaphragm 22 is preferably formed with a disk protrusion 223 having a center coinciding with the center of the receiving protrusion 21 to increase the strain of the attachment surface to which the strain gauge 23 is attached. .

The disc protrusion 223 makes the thickness of the central portion of the diaphragm relatively thick, so that the deformation of the center portion where the disc protrusion 223 is formed is small and the edge portion where the strain gauge is relatively attached, that is, the attachment surface 224. To increase the strain. That is, by increasing the slope of the strain in Figure 9 it is possible to react sensitively to small changes in tension to be measured.

1 is a perspective view showing a state of use of the electronic parking brake tension sensing device according to an embodiment of the present invention.

Figure 2 is an exploded perspective view of the electronic parking brake tension sensing device shown in FIG.

3 is a perspective view partially cut in the joint portion employed in the electronic parking brake tension sensing device shown in FIG.

4 is a cross-sectional view taken along line AA of FIG. 3.

5 is a plan view of the electronic parking brake tension sensing device shown in FIG.

6 is an enlarged view of a portion B of FIG. 5, (a) is a plan view showing before deformation, and (b) is a plan view showing after deformation.

7 is a cross-sectional view of the sensing body along the line C-C of FIG.

8 is a view for explaining the basic principle applied to the present invention.

9 is a graph showing a local strain of the diaphragm employed in the electronic parking brake tension sensing device shown in FIG.

10 shows a conventional technique.

Explanation of symbols on the main parts of the drawings

100: sensing device

1 hooker part

11: engaging groove Z: stress dispersion plane 12: engaging projection

2: sensing body

21: receiving projection 22: diaphragm 221: notch groove

222: slope slope 223: disk protrusion 23: strain gauge

3: joint part

31: bottom 311: stress distribution hole 32: side

33: rear section 334: fixed groove Z: stress distribution surface

4: brake wire

5: tension control shaft

D: locking member D1: mounting head

Claims (5)

A hooker portion 1 to which the brake wire 4 is fixed; A sensing body part (2) coupled to the hooker part (1) for measuring a tensile force of the brake wire (4) through a diaphragm (22) to which a semiconductor strain gauge (23) is attached; And And a joint part (3) coupled to the sensing body part (2) and having a tension control shaft (5) fixed at a rear end thereof. In claim 1, The rear portion of the joint portion 3 has a rectangular appearance in which the bottom surface 31 and both side surfaces 32 form a circumference, and a rear end of the joint portion 3 is provided with a fixing groove 334 to which the tension control shaft 5 is fixed. The rear end surface 33 is formed, Electronic parking brake tension sensing device, characterized in that the bottom surface 31 is formed by drilling a stress distribution hole (311) to evenly distribute the stress distribution in the joint portion (3). In claim 2, Mounting heads D1 are formed at ends of the brake wire 4 and the tension control shaft 5, Each mounting head D1 is locked to the locking groove 11 and the fixing groove 334 formed in front of the hooker portion 1, The outer grooves (P) of the engaging grooves (11) and the fixing grooves (334) are electronic parking brake tension sensing device, characterized in that to form a sloped stress distribution surface (Z) to relieve concentrated stress. In claim 1, On the front of the sensing body portion 2, Receiving protrusion 21 is protruded from the center and coupled to the hook portion, and an annular notched groove 221 is formed around the center, Electronic parking brake tension sensing device between the notch groove 211 and the receiving projection 21, characterized in that the non-inclined slope 222 is formed to increase the linear rate of change of the diaphragm (22). In claim 4, The diaphragm 22 is further formed with a disk protrusion 223 having a center coinciding with the center of the receiving protrusion 21 to increase the strain of the attachment surface to which the strain gauge 23 is attached. Electronic parking brake tension sensing device.

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