JP2015110967A - Actuator unit for drum-type electric parking brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a structure which can inexpensively prevent the intrusion of water into a case of an actuator unit which constitutes a drum-type electric parking brake device via a cable 6a composed of a stranded wire.SOLUTION: In a cable 6a, a portion which is exposed between a connecting implement 8a attached to a tip part and a dust prevention boot 7a covering a portion exposed from a case is covered with a waterproof member 32 which can prevent the passage of a water component, and has flexibility. In a state that a part of the waterproof member 32 is inserted into a bottomed hole 31 which constitutes the connecting implement 8a, a portion existing around the bottomed hole 31 in the connecting implement 8a is elastically deformed to the inside of a radial direction, and the connecting implement 8a is caulked and fixed to the tip part of the cable 6a.

Description

The present invention relates to an improvement of an actuator unit for a drum-type electric parking brake device that is used by being incorporated in a drum-type electric parking brake device that generates a braking force by increasing the distance between a pair of brake shoes by an electric motor. Specifically, the present invention relates to a structure for preventing moisture from entering a case where an electric motor or the like is installed.
The drum type electric parking brake device has a structure in which the drum brake is used as both a service brake for decelerating or stopping the vehicle from a running state and a parking brake for maintaining the stopped state. Also included is a drum-in disc brake, which is performed by a disc brake and only a parking brake is performed by a drum brake.

  It has been practiced to incorporate a parking brake device in a drum brake that keeps the vehicle in a stopped state without depressing the brake pedal. Also, parking brakes can be mechanically (non-hydraulic) using an electric motor as a drive source and via a force-increasing mechanism such as a toggle mechanism, as described in Patent Document 1, for example. It is known from and implemented in some vehicles. Patent Document 1 describes a structure in which a service brake is performed by a hydraulic disc brake and a parking brake is performed by a mechanical drum brake using an electric motor as a drive source. In Patent Document 1, the distance between a pair of brake shoes supported on the outer surface of the backing plate so as to be able to displace the backing plate in the radial direction is extended using an electric actuator unit. The structure of the drum-type electric parking brake device configured as described above is described.

FIG. 8 shows an actuator unit 1 which is different from the structure described in Patent Document 1, but which the present inventors previously considered.
The actuator unit 1 includes a case 2 having a sealed structure, an electric motor 3, a gear type reduction gear 4, a feed screw mechanism 5, a cable (twisted cable) 6, a dustproof boot 7, and a connector 8. . Of these, the electric motor 3, the gear speed reducer 4, and the feed screw mechanism 5 are installed in the case 2, and the rotation of the output shaft 9 of the electric motor 3 is transmitted via the gear speed reducer 4. Then, it is transmitted to the screw cylinder 10 constituting the feed screw mechanism 5. The screw cylinder 10 is supported in the case 2 so as to be rotatable only, and has an internal thread formed on the inner peripheral surface. Inside the screw cylinder 10, a rod 11 that constitutes the feed screw mechanism 5 together with the screw cylinder 10 is provided in a state in which it cannot be rotated, and is formed on the outer peripheral surface of the rod 11. A male screw is screwed into a female screw formed on the inner peripheral surface of the screw cylinder 10. Thereby, when this screw cylinder 10 rotates, the said rod 11 moves only to an own axial direction.

  Further, the base end portion of the cable 6 is coupled and fixed to the distal end portion of the rod 11. As shown in FIG. 9, the cable 6 is a stranded wire composed of a plurality of metal wires 12 and 12. The dustproof boot 7 has a base end portion fixed to the case 2 and covers a portion of the cable 6 that protrudes from the case 2. Further, the bifurcated connecting tool 8 is coupled and fixed to a portion protruding from the tip of the dustproof boot 7 in the tip of the cable 6. The case 2 is supported and fixed to a fixed portion such as a backing plate or a knuckle in a state where the actuator unit 1 having such a configuration is incorporated in a parking brake device. It pivotally supports a part of the structural member of the expansion mechanism such as a link mechanism for expanding the interval between the circumferential ends of the pair of brake shoes.

  At the time of braking, the electric motor 3 is energized, and the rod 11 is linearly moved away from the expansion mechanism (downward in FIG. 8) based on the threaded engagement of the female screw of the screw cylinder 10 and the male screw of the rod 11. Move. The rod 11 is used to pull the cable 6 and extend the expansion mechanism to widen the distance between the pair of brake shoes, and press the linings of both brake shoes against the inner peripheral surface of the drum to increase the braking force. Cause it to occur.

However, in the case of the actuator unit 1 having the above-described configuration, there is a possibility that moisture may enter the case 2, and the electric motor 3 may fail, the gear reducer 4 or the feed screw mechanism 5. There is a possibility that problems such as sticking due to rust will occur.
That is, since the actuator unit 1 is exposed to the outside air in a use state, the temperature in the case 2 may suddenly decrease from a high temperature state, and the air pressure in the case 2 may change to a negative pressure. . When the pressure in the case 2 becomes negative in this way, the outside air tends to be sucked into the case 2 through the gaps 13 and 13 existing between the wires 12 and 12 constituting the cable 6. Here, in the cable 6, a portion existing between the dustproof boot 7 and the connection tool 8 is directly exposed to the outside, so that moisture is absorbed from the portion to the inside of the case 2. There is a possibility of moisture intrusion. As a result, there is a possibility that the electric motor 3 breaks down or rust is generated on each member constituting the gear transmission 4 and the feed screw mechanism 5.

In order to solve the above problems, for example, Patent Documents 2 and 3 disclose the following structures.
Among these, Patent Document 2 discloses a structure in which an opening is provided in a part of a case constituting the actuator unit, and the opening is closed by a thin film diaphragm. According to such a structure, when the temperature in the case suddenly decreases, the pressure in the case can be prevented from changing to a negative pressure by deforming the diaphragm toward the inside of the case. For this reason, it can suppress that a water | moisture content permeates in this case through the cable which consists of a strand wire.

  On the other hand, Patent Document 3 discloses a structure in which an emergency release mechanism is provided in a vehicle compartment in a state where it communicates with a case constituting an actuator unit, and an opening of the emergency release mechanism is closed with a filter. According to such a structure, when the temperature in the case rapidly decreases, the air pressure in the case can be prevented from changing to a negative pressure by sucking air into the case through the filter. For this reason, it can suppress that a water | moisture content permeates in this case through the cable which consists of a strand wire.

  As described above, in any of the structures of Patent Documents 2 and 3, it is possible to suppress the ingress of moisture into the case, and it is possible to prevent the electric motor or the like disposed in the case from failing. However, in any of the structures of Patent Documents 2 and 3, it is difficult to completely prevent the atmospheric pressure in the case from changing to a negative pressure, and it is possible for moisture to enter into the case. There is sex. In addition, the structure for suppressing the ingress of moisture is complicated, and it is inevitable that the cost increases.

JP-T-2001-504417 Japanese Patent No. 5130294 Japanese Patent No. 4697454

  In view of the circumstances as described above, the present invention was invented to realize a structure capable of preventing moisture from entering through a cable into a case constituting an actuator unit at a low cost.

The actuator unit for a drum type electric parking brake device of the present invention includes a case, an electric motor, a conversion mechanism, a cable, a dustproof boot, and a connector.
And this connecting tool is connected to the components of the extension mechanism provided between the ends of the pair of brake shoes, and the extension mechanism is extended by pulling the cable based on the drive of the electric motor. The braking force is generated by expanding the distance between the circumferential ends of the two brake shoes and pressing the linings of the two brake shoes against the inner peripheral surface of the drum rotating together with the wheels.
The electric motor is a power source of the actuator unit for the drum type electric parking brake device, and is installed in the case.
The conversion mechanism is, for example, a feed screw mechanism, and converts the rotational motion of the output shaft of the electric motor into linear motion.
The cable is a stranded wire composed of a plurality of wires, and a base end portion is connected to a part of the linear motion member constituting the conversion mechanism, and an intermediate portion or a distal end portion protrudes from the case. ing.
The dustproof boot has a base end fixed to the case and covers a portion of the cable protruding from the case.
Moreover, the said connection tool is fixed to the part protruded from the front-end | tip part of the said dustproof boot among the front-end | tip parts of the said cable.

In particular, the actuator unit for the drum-type electric parking brake device according to the present invention includes a waterproof member (for example, a coating film of nylon resin or the like) at least a portion of the cable exposed between the connection tool and the dustproof boot. Or a synthetic resin such as rubber or plastic, or a cylindrical body made of heat shrinkable material).
Further, the cable is inserted inside the bottomed hole formed in the connection tool in a state including a portion covered with the waterproof member, and around the bottomed hole in the connection tool. The connector is caulked and fixed to the tip of the cable by plastically deforming the existing portion radially inward.

When implementing the actuator unit for a drum type electric parking brake device of the present invention as described above, preferably, as in the invention described in claim 2, for example, the back of the bottomed hole in the end portion of the cable is used. The part inserted into the part is exposed without being covered with the waterproof member.
Further, when carrying out the invention described in claim 2 as described above, preferably, as in the invention described in claim 3, for example, the bottomed hole is divided into a large-diameter portion on the opening side and a back side. And a stepped hole having a small diameter portion. A portion of the cable end covered with the waterproof member is disposed on the large diameter portion, and the cable end is covered with the waterproof member on the small diameter portion. Place no part.

  Moreover, when implementing the actuator unit for drum type electric parking brake apparatuses of this invention, Preferably, the tip part of the said dustproof boot is fixed among the said cables like the invention described in Claim 4, for example. The portion is covered with the waterproof member.

  Further, when the actuator unit for the drum type electric parking brake device of the present invention is implemented, a retaining ring is preferably caulked and fixed around the tip of the dustproof boot, for example, as in the invention described in claim 5. .

  Furthermore, when implementing the actuator unit for drum-type electric parking brake devices of the present invention, preferably, the waterproof member is made of a heat-shrinkable material such as polyolefin as in the invention described in claim 6.

According to the actuator unit for a drum type electric parking brake device of the present invention having the above-described configuration, a structure capable of preventing moisture from entering through a cable into a case constituting the actuator unit can be realized at low cost.
That is, in the case of the present invention, at least a portion of the cable that is exposed between the connection tool and the dustproof boot is covered with a waterproof member, and the connection tool is covered at the tip of the cable with the waterproof member. Caulking is fixed with the covered part included. For this reason, the cable can be covered with the connection tool, the waterproof member, and the dustproof boot in order from the tip side, and the portion directly exposed to the outside can be eliminated, and the connection tool and the cable The sealing property of the connection part can be secured.
Therefore, even when the temperature in the case suddenly decreases, moisture can be prevented from being absorbed from the gaps between the wires constituting the cable, and moisture can be absorbed from the connecting portion. It can be effectively prevented.
Moreover, the structure of covering the cable with the waterproof member can be formed by forming a coating film such as nylon resin on the cable or by fitting a cylindrical body made of synthetic resin such as rubber or plastic. Therefore, it can be realized at low cost.
As a result, according to the present invention, a structure that can prevent moisture from entering through the cable into the case constituting the actuator unit can be realized at low cost.

Moreover, according to the invention described in Claims 2 and 3, it is possible to sufficiently secure the coupling strength of the connector to the cable.
In addition, according to the inventions described in claims 4 and 5, since the sealing performance of the connection portion between the cable and the dustproof boot can be enhanced, it is possible to more effectively prevent moisture from entering the case.
Furthermore, according to the invention described in claim 6, since the waterproof member can be closely attached around the cable, high waterproof performance can be exhibited and positioning with respect to the cable can be achieved.

The perspective view which shows one example of embodiment of this invention in the state seen from the outer side and radial direction outer side except the drum. The perspective view shown in the state seen similarly from FIG. 1 regarding the radial direction. The orthographic view shown in the state similarly seen from the outer side. The front view which similarly takes out and shows an actuator unit. FIG. 5 is a cross-sectional view taken along the line aa in FIG. 4. The b section enlarged view of FIG. 5 similarly. The schematic diagram which shows the state in which the waterproof member was externally fitted or the film was similarly formed in the front-end | tip part of the cable. The longitudinal cross-sectional view of an actuator unit which shows the structure considered previously. The schematic diagram which similarly shows the front-end | tip part of a cable.

  1 to 7 show an example of an embodiment of the present invention. The structure of this example is shown when the present invention is applied to a drum-in-disc brake. The drum type electric parking brake device of the present example includes a backing plate 14, a pair of brake shoes 15, 15, a drum (not shown), an anchor 16, and an electric actuator unit 1a. Among these, the backing plate 14 is screwed and fixed to the outer surface of the knuckle that constitutes the suspension device.

  The backing plate 14 is formed by pressing a metal plate having sufficient strength and rigidity, such as a steel plate, to form a substantially annular shape with a part of the portion near the outer diameter missing, and a bent portion is formed at the outer peripheral edge portion. Bending rigidity is improved by forming a step part in the main part while forming. The notch 17 formed in a part near the outer diameter is formed for disposing a support or caliper that constitutes a disc brake that is a service brake. The backing plate 14 having such a configuration is coupled and fixed to the frame portion 18 of the knuckle by a plurality of (for example, about four) bolts.

  Each of the brake shoes 15 and 15 is fixed to the outer surface of the back plate 20 and the back plate 20 fixed along the outer peripheral edge of the web 19. It consists of a lining 21. The brake shoes 15 and 15 each having such a configuration are supported on the outer surface of the backing plate 14 so as to be capable of displacement in the radial direction of the backing plate 14. The structure of this example uses a duo-servo type drum brake as a parking brake device. For this purpose, both ends in the circumferential direction of the anchor 16 in which the circumferential edges of the webs 19, 19 of the brake shoes 15, 15 (the upper circumferential edge in FIGS. 1 to 3) are fixed to the outer surface of the backing plate 14. The surface is in contact with or in close proximity (the anchor side in non-braking and braking is in contact, and the non-anchor side in braking is in close proximity). Further, the other circumferential edges of the webs 19, 19 of the brake shoes 15, 15 (lower circumferential edges in FIGS. 1 to 3) are abutted against both axial ends of the floating anchor 22. Further, return springs 23a and 23b are spanned between the webs 19 and 19 of the two brake shoes 15 and 15, and the brake shoes 15 and 15 are directed radially inward (in the brake releasing direction). Gives elasticity.

  The drum is provided so as to surround the brake shoes 15 and 15 in a state where the drum is coupled and fixed to the rotation side flange of the hub unit supported by the knuckle, and rotates together with the wheels. Since the structure of this example is a drum-in disc brake, a disc provided on the outer diameter side of the drum and provided integrally with the drum is used. A pair of pads supported by a support or caliper disposed in the notch 17 of the backing plate 14 is disposed with the disk sandwiched from both sides in the axial direction. When the service brake is activated, the disk is strongly held from both sides by the two pads. The anchor 16 is supported and fixed by a plurality of sets of bolts and nuts at a part of the outer surface of the backing plate 14 and between the circumferential ends of the brake shoes 15 and 15.

The actuator unit 1a includes a case 2a having a sealed structure, an electric motor 3a, a gear type speed reducer 4a which is a speed reduction mechanism, a feed screw mechanism 5a which is a conversion mechanism described in claims, a cable ( A twisted cable) 6a, a dustproof boot 7a, and a connector 8a.
The case 2a is composed of a case main body 37 and a lid 38, and the opening of the case main body 37 is sealed with the lid 38 so that the cable 6a protrudes to the outside. Therefore, the sealing of the internal space is ensured except for the opening provided in the lid 38. The case body 37 and the lid body 38 are made of a synthetic resin or a metal such as an aluminum alloy. The electric motor 3a, the gear type reduction gear 4a, and the feed screw mechanism 5a are installed in such a case 2a, and the rotation of the output shaft 9a of the electric motor 3a is controlled by the gear type reduction gear 4a. Then, it is transmitted to the screw cylinder 10a constituting the feed screw mechanism 5a. The screw cylinder 10a is supported in the case 2a so as to be rotatable only, and an internal thread is formed on the inner peripheral surface. Inside the screw cylinder 10a, the rod 11a, which is the linear motion member described in the claims and which constitutes the feed screw mechanism 5a together with the screw cylinder 10a, is provided in a state in which rotation is disabled. The male screw formed on the outer peripheral surface of the rod 11a is screwed into the female screw formed on the inner peripheral surface of the screw cylinder 10a. Thereby, when this screw cylinder 10 rotates, the said rod 11a moves only to an own axial direction.

  The proximal end portion of the cable 6a is coupled and fixed to the distal end portion of the rod 11a. As shown in FIG. 7, the cable 6a is a stranded wire made of a plurality of metal wires 12a and 12a. The dustproof boot 7 a is made of an elastic material (for example, made of synthetic rubber such as acrylonitrile butadiene rubber (NBR)), and has a hollow bellows-like main body portion 24 and cylindrical connecting portions provided at both ends of the main body portion 24. 25a, 25b. Then, the connecting portion 25b provided at the base end portion of the dustproof boot 7a is connected to the lead-out cylinder portion 26 having a bowl-shaped cross section provided around the opening portion of the lid portion 38 constituting the case 2a. While being fitted and fixed in a state where it is prevented from coming off in the axial direction, a connecting portion 25a provided at the front end is fitted and fixed to a portion near the tip of the cable 6a. In the case of this example, a metal-made cylindrical retaining ring 27 is externally fitted and fixed around the connecting portion 25a. The dustproof boot 7a covers a portion of the cable 6a that protrudes from the case 2a while being fixed to the case 2a.

  Further, the bifurcated connecting tool 8a is coupled and fixed to a portion of the tip end portion of the cable 6a that protrudes from the tip end portion (the connecting portion 25a) of the dustproof boot 7a. This connecting tool 8a is integrally formed by forging or die-casting a metal material, or by injection-molding a high-performance resin. Is a cylindrical connecting portion 28. That is, the front half of the connection tool 8a includes a pair of connection plate portions 29 and 29 arranged substantially parallel to each other with a space therebetween, and the connection plate portions 29 and 29 are aligned with each other. Attachment holes 30 and 30 are formed, respectively. In addition, a bottomed hole 31 that opens only at the base end surface is formed at the center of the connecting portion 28 that constitutes the base half of the connector 8a. The bottomed hole 31 is a stepped hole having a large-diameter portion 39 on the opening side and a small-diameter portion 40 on the back side, and the inner diameter of the small-diameter portion 40 is the outer diameter of the cable 6a. The inner diameter dimension of the large-diameter portion 39 is slightly larger than the outer diameter dimension of the waterproof member 32. Therefore, the end portions of the cable 6 a and the waterproof member 32 can be loosely inserted inside the bottomed hole 31.

  In particular, in the case of this example, at least a portion of the cable 6a exposed between the connection tool 8a and the dustproof boot 7a can prevent (block) the passage of moisture and be made of a flexible material. It is covered with a waterproof member 32 made of. The waterproof member 32 is formed of, for example, a coating film such as nylon resin or vinyl chloride resin, or a synthetic resin such as rubber (including synthetic rubber) or plastic, or a cylindrical body made of a heat shrink material such as polyolefin. . That is, the coating film formed so as to cover the outer peripheral surface of the cable 6a may be used as the waterproof member 32, or the waterproof member 32 previously formed in a cylindrical shape (cylindrical or rectangular cylindrical shape) may be attached to the cable 6a. It may be fitted and fixed {when a waterproof member 32 made of a heat shrink material is used, after the waterproof member 32 is externally fitted, it is heated and shrunk (reduced diameter)}. In any case, in the case of this example, the axial length of the waterproof member 32 having such a configuration is ensured to be longer than the portion exposed between the connector 8a and the dustproof boot 7a. Accordingly, the tip end portion is arranged inside the bottomed hole 31 (large diameter portion 39) constituting the connecting tool 8a, and the base half portion is arranged on the inner diameter side of the connecting portion 25a constituting the dustproof boot 7a. I try to do it. However, the axial length of the waterproof member 32 is regulated so that a bare portion 33 that is an exposed portion that is not covered by the waterproof member 32 is left at the tip of the cable 6a.

  In the case of this example, the connecting tool 8a is fixed to the tip of the cable 6a as described above as follows. That is, in the state where the portion covered with the bare portion 33 and the waterproof member 32 is inserted into the bottomed hole 31 formed in the connector 8a, the tip of the cable 6a. The part (connection part 28) which exists in the circumference | surroundings of the bottomed hole 31 among 8a is plastically deformed to radial inside. More specifically, a portion of the end of the cable 6a covered by the waterproof member 32 is disposed on the large-diameter portion 39 on the opening side of the bottomed hole 31, and the bottomed hole 31 The connecting portion 28 is plastically deformed radially inward in a state in which the bare portion 33 of the distal end portion of the cable 6a is disposed in the small-diameter portion 40 on the back side. As a result, the connecting tool 8a is caulked and fixed to the tip of the cable 6a. Further, in order to fix the tip end portion (connecting portion 25a) of the dustproof boot 7a to a portion near the tip end of the cable 6a, the waterproof member 32 of the cable 6a is covered with the waterproof member 32 on the inner diameter side of the connecting portion 25a. Place the broken part. In this state, the retaining ring 27 is disposed around the connecting portion 25a, and the retaining ring 27 is plastically deformed (caulked) radially inward. Thereby, the connecting portion 25a is externally fitted and fixed to a portion of the cable 6a covered with the waterproof member 32.

  A link mechanism 34, which is a toggle type expansion mechanism, is provided adjacent to the anchor 16 in order to increase the distance between the brake shoes 15 and 15 when driven by the actuator 1a. The link mechanism 34 has a structure that has been generally implemented in the technical field of a parking brake device for a drum brake. The link mechanism 34 is formed by connecting a pair of link arms 35a and 35b so as to be swingable and displaceable by a pivot 36. . The webs 19 and 19 constituting the brake shoes 15 and 15 are formed in locking recesses formed at the center of the base edges (edges opposite to each other) of the link arms 35a and 35b. One end of the direction is abutted. Further, a portion adjacent to both the locking recesses is abutted against a portion having a sufficient strength and rigidity provided in a portion fixed to the backing plate 14, so that both the link arms 35a and 35b Oscillating displacement is possible with the abutting part as a fulcrum. Of these link arms 35a and 35b, one link arm 35a is provided between the other link arms 35b. For this purpose, the other link arm 35b is configured by folding back an intermediate portion of a metal plate as a material by 180 degrees. In addition, the front end portion of the cable 6a is stretched over the pair of attachment holes 30 and 30 formed in the connection tool 8a to the front end portion (the right end portion in FIGS. 2 to 3) of one link arm 35a. The coupling is performed by using a connecting pin (not shown) provided.

  In the case of the drum-type electric parking brake device of the present example having the above-described configuration, during braking, the electric motor 3a is energized, and based on the threaded engagement of the female screw of the screw cylinder 10a and the male screw of the rod 11a, The rod 11a is linearly moved in a direction away from the link mechanism 34 (downward in FIGS. 4 to 6). Then, the cable 6a is pulled by the rod 11a and the link mechanism 34 is extended to widen the distance between the brake shoes 15 and 15, and the linings 21 and 21 of the brake shoes 15 and 15 are moved inside the drum. Press against the peripheral surface to generate braking force.

In particular, in the case of the structure of this example, a structure that can prevent moisture from entering through the cable 6a into the case 2a constituting the actuator unit 1a can be realized at low cost.
That is, in the case of this example, a portion of the cable 6a exposed between the connection tool 8a and the dustproof boot 7a is covered with the waterproof member 32, and the connection tool 8a is covered with the cable 6a. The tip portion is caulked and fixed in a state including a portion covered with the waterproof member 32. For this reason, the cable 6a can be covered with the connecting tool 8a, the waterproof member 32, and the dustproof boot 7a in order from the distal end side, and the portion directly exposed to the outside can be eliminated. Moreover, the sealing property of the connection part of the said connection tool 8a and the said cable 6a is securable. Therefore, even when the temperature in the case 2a suddenly decreases, moisture can be prevented from being absorbed from the gaps 13a, 13a between the wires 12a, 12a constituting the cable 6a, and the connecting portion. It is also possible to effectively prevent moisture from being absorbed. Moreover, the structure in which the cable 6a is covered by the waterproof member 32 is formed by forming a coating film such as nylon resin on the cable 6a or by fitting a cylindrical body made of synthetic resin such as rubber or plastic ( When it is made of heat shrinkable material, it can be realized at low cost because it can be configured by heating after external fitting. As a result, according to the structure of this example, a structure that can prevent moisture from entering through the cable 6a into the case 2a constituting the actuator unit 1a can be realized at low cost. Further, when the waterproof member 32 is made of a heat-shrinkable material, the waterproof member 32 can be brought into close contact with the periphery of the cable 6a, so that high waterproof performance can be exhibited and positioning with respect to the cable 6a can be performed. You can also plan.

  In the case of this example, the connecting tool 8a (connecting portion 28) is not only a portion of the cable 6a covered by the waterproof member 32 but also a bare portion not covered by the waterproof member 32. It can be directly swaged to 33. For this reason, the coupling strength of the connector 8a with respect to the cable 6a can be sufficiently ensured.

  Furthermore, in the case of this example, the portion of the cable 6a covered by the waterproof member 32 is disposed on the inner diameter side of the connecting portion 25a of the dustproof boot 7a (superposed in the radial direction). The connecting portion 25a is externally fixed to the cable 6a. For this reason, the sealing property of the connection part of this cable 6a and the said dustproof boot 7a can be improved. Therefore, it is possible to more effectively prevent moisture from entering the case 2a.

  The present invention is not limited to the drum-in-disc brake as shown in the figure, and can be implemented by a structure in which both the service brake and the parking brake are performed by the drum brake. Further, the drum brake structure is not limited to the duo servo type as shown in the figure, and other structures such as a leading trailing type may be employed.

1, 1a Actuator unit 2, 2a Case 3, 3a Electric motor 4, 4a Gear speed reducer 5, 5a Lead screw mechanism 6, 6a Cable (twisted cable)
7, 7a Dust-proof boots 8, 8a Connector 9, 9a Output shaft 10, 10a Screw cylinder 11, 11a Rod 12, 12a Wire material 13, 13a Gap 14 Backing plate 15 Brake shoe 16 Anchor 17 Notch 18 Frame part 19 Web 20 Back plate 21 Lining 22 Floating anchors 23a, 23b Return spring 24 Body portion 25a, 25b Connecting portion 26 Leading cylinder portion 27 Retaining ring 28 Connection portion 29 Connection plate portion 30 Mounting hole 31 Bottomed hole 32 Waterproof member 33 Bare portion 34 Link mechanism 35a, 35b Link arm 36 Axis 37 Case body 38 Lid 39 Large diameter part 40 Small diameter part

Claims (6)

Case and
An electric motor as a power source installed in the case;
A conversion mechanism that converts the rotational motion of the output shaft of the electric motor into linear motion;
A cable, which is a stranded wire composed of a plurality of wires, with a base end portion connected to a part of the linear motion member constituting the conversion mechanism, and an intermediate portion or a tip portion protruding from the case,
A base end portion is fixed to the case, and a dustproof boot that covers a portion of the cable protruding from the case;
A drum type electric parking brake device actuator unit comprising a connection tool fixed to a portion protruding from the tip of the dustproof boot among the tip of the cable,
Of the cable, at least a portion exposed between the connector and the dustproof boot is covered with a waterproof member,
The tip of the cable is inserted inside the bottomed hole formed in the connection tool in a state including the portion covered by the waterproof member, and exists around the bottomed hole in the connection tool. The connector is caulked and fixed to the tip of the cable by plastically deforming the portion radially inward,
This is an actuator unit for drum-type electric parking brake devices.   2. The actuator unit for a drum-type electric parking brake device according to claim 1, wherein a portion of the front end portion of the cable that is inserted into a deep portion of the bottomed hole is not covered with the waterproof member.   The bottomed hole is a stepped hole having a large-diameter portion on the opening side and a small-diameter portion on the back side, and the large-diameter portion of the bottomed hole is formed by the waterproof member among the distal end portions of the cable. The actuator for a drum-type electric parking brake device according to claim 2, wherein a covered portion is disposed, and a portion of the distal end portion of the cable that is not covered with the waterproof member is disposed in the small diameter portion. unit.   The actuator for a drum-type electric parking brake device according to any one of claims 1 to 3, wherein a portion of the cable to which the tip of the dustproof boot is fixed is covered with the waterproof member. unit.   The actuator unit for a drum-type electric parking brake device according to any one of claims 1 to 4, wherein a retaining ring is fixed by caulking around a front end portion of the dustproof boot. The actuator unit for a drum-type electric parking brake device according to any one of claims 1 to 5, wherein the waterproof member is made of a heat-shrinkable material.

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