US20240010177A1 - Electric parking brake device - Google Patents
Electric parking brake device Download PDFInfo
- Publication number
- US20240010177A1 US20240010177A1 US18/370,576 US202318370576A US2024010177A1 US 20240010177 A1 US20240010177 A1 US 20240010177A1 US 202318370576 A US202318370576 A US 202318370576A US 2024010177 A1 US2024010177 A1 US 2024010177A1
- Authority
- US
- United States
- Prior art keywords
- screw shaft
- brake
- brake cable
- cylindrical portion
- rotation restricting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000003780 insertion Methods 0.000 claims description 24
- 230000037431 insertion Effects 0.000 claims description 24
- 238000006243 chemical reaction Methods 0.000 claims description 13
- 230000007246 mechanism Effects 0.000 claims description 9
- 230000008859 change Effects 0.000 claims description 6
- 230000008602 contraction Effects 0.000 description 11
- 230000004044 response Effects 0.000 description 3
- 210000000078 claw Anatomy 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/74—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive
- B60T13/746—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive and mechanical transmission of the braking action
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/74—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive
- B60T13/741—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive acting on an ultimate actuator
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D51/00—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like
- F16D51/16—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis
- F16D51/18—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes
- F16D51/20—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes extending in opposite directions from their pivots
- F16D51/22—Brakes with outwardly-movable braking members co-operating with the inner surface of a drum or the like shaped as brake-shoes pivoted on a fixed or nearly-fixed axis with two brake-shoes extending in opposite directions from their pivots mechanically actuated
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/14—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position
- F16D65/16—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake
- F16D65/22—Actuating mechanisms for brakes; Means for initiating operation at a predetermined position arranged in or on the brake adapted for pressing members apart, e.g. for drum brakes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T1/00—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles
- B60T1/02—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels
- B60T1/06—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels acting otherwise than on tread, e.g. employing rim, drum, disc, or transmission or on double wheels
- B60T1/067—Arrangements of braking elements, i.e. of those parts where braking effect occurs specially for vehicles acting by retarding wheels acting otherwise than on tread, e.g. employing rim, drum, disc, or transmission or on double wheels employing drum
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2121/00—Type of actuator operation force
- F16D2121/18—Electric or magnetic
- F16D2121/24—Electric or magnetic using motors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2125/00—Components of actuators
- F16D2125/18—Mechanical mechanisms
- F16D2125/20—Mechanical mechanisms converting rotation to linear movement or vice versa
- F16D2125/34—Mechanical mechanisms converting rotation to linear movement or vice versa acting in the direction of the axis of rotation
- F16D2125/40—Screw-and-nut
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2125/00—Components of actuators
- F16D2125/18—Mechanical mechanisms
- F16D2125/44—Mechanical mechanisms transmitting rotation
- F16D2125/46—Rotating members in mutual engagement
- F16D2125/48—Rotating members in mutual engagement with parallel stationary axes, e.g. spur gears
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2125/00—Components of actuators
- F16D2125/18—Mechanical mechanisms
- F16D2125/58—Mechanical mechanisms transmitting linear movement
- F16D2125/582—Flexible element, e.g. spring, other than the main force generating element
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D2125/00—Components of actuators
- F16D2125/18—Mechanical mechanisms
- F16D2125/58—Mechanical mechanisms transmitting linear movement
- F16D2125/60—Cables or chains, e.g. Bowden cables
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H2025/2031—Actuator casings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H2025/2062—Arrangements for driving the actuator
- F16H2025/2075—Coaxial drive motors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H2025/2062—Arrangements for driving the actuator
- F16H2025/2081—Parallel arrangement of drive motor to screw axis
Definitions
- the present invention relates to an electric parking brake device including a screw shaft that is connected to a brake cable; an actuator case that supports the screw shaft movably in an axial direction thereof; an electric motor that is supported by the actuator case rotatably forward and backward; a motion conversion mechanism that has a nut to be screwed onto the screw shaft, enables conversion from a rotational motion generated in the electric motor to a linear motion of the screw shaft, and is accommodated in the actuator case; and a rotation restricting means that restricts a rotational motion of the screw shaft, in which switching between a parking brake state reached by pulling the brake cable and a non-parking brake state reached by loosening the brake cable is performed by a change in a rotational direction of the electric motor.
- An electric parking brake device that switches between a state in which a parking brake force is obtained by pulling a brake cable and a state in which a parking brake force is released by loosening the brake cable by a change in the rotational direction of an electric motor is known in PTL 1.
- the electric parking brake device disclosed in PTL 1 has a rotation restricting means, configured by a projection portion provided in the screw shaft and a groove formed in the actuator case so as to be entered by the projection portion, for restricting the rotation of the screw shaft, since a clearance is present between the projection portion and the groove, the projection portion collides with the side surface of the groove and causes a slapping sound when the rotational direction of the screw shaft is changed to switch between the parking brake state and the parking brake release state and may cause a large operating sound.
- the projection portion is kept pressed strongly against the side surface of the groove during movement in the axial direction of the screw shaft when a rotational motion is restricted by the rotation restricting means, the sliding resistance of the projection portion becomes large, thereby increasing wear of the projection portion and the actuator case.
- the invention addresses the above situation with an object of providing an electric parking brake device that reduces an operating sound during switching between the parking brake state and the parking brake release state and reduces wear of members constituting the rotation restricting means.
- an electric parking brake device including a screw shaft that is connected to a brake cable; an actuator case that supports the screw shaft movably in an axial direction thereof; an electric motor that is supported by the actuator case rotatably forward and backward; a motion conversion mechanism that has a nut to be screwed onto the screw shaft, enables conversion from a rotational motion generated in the electric motor to a linear motion of the screw shaft, and is accommodated in the actuator case; and a rotation restricting means that restricts a rotational motion of the screw shaft, in which switching between a parking brake state reached by pulling the brake cable and a non-parking brake state reached by loosening the brake cable is performed by a change in a rotational direction of the electric motor, in which the brake cable is formed by twisting a plurality of wires so as to generate a twisting force in a fixed direction when the brake cable is pulled, and a direction in which the twisting force generated by the brake cable in a pulled
- the rotation restricting means includes a plurality of rotation restricting projection portions that are provided in an end portion of the screw shaft opposite to the brake cable and radially project from the screw shaft and a plurality of rotation restricting grooves formed in the actuator case or an insertion member accommodated and fixed in the actuator case and entered by the rotation restricting projection portions.
- the twisting force for rotationally biasing the screw shaft to the side loosening the brake cable acts on the screw shaft from the brake cable when the brake cable is pulled, it is possible to prevent components constituting the rotation restricting means from strongly colliding with each other during switching from the parking brake state to the parking brake release state, suppress the generation of a slapping sound, and reduce the operating sound.
- the screw shaft is moved in the axial direction to enter the parking brake state by pulling the brake cable, it is possible to prevent components constituting the rotation restricting means from strongly colliding with each other, reduce the driving torque of the electric motor by reducing the sliding resistance, and reduce wear of members constituting the rotation restricting means.
- the operating sound can be reduced more effectively by restricting the rotation of the screw shaft at a plurality of positions in the circumferential direction of the screw shaft.
- FIG. 1 is a front view illustrating a drum brake device (first embodiment).
- FIG. 2 is a sectional view taken along line 2 - 2 in FIG. 1 (first embodiment).
- FIG. 3 is a perspective view seen along arrow 3 in FIG. 1 (first embodiment).
- FIG. 4 is a sectional view, taken along line 4 - 4 in FIG. 3 , that illustrates the state in which a brake cable is being loosened (first embodiment).
- FIG. 5 is a sectional view, corresponding to FIG. 4 , that illustrates the state in which the brake cable has been pulled (first embodiment).
- FIG. 6 is a perspective view illustrating an electric actuator (first embodiment).
- FIG. 7 is an enlarged view illustrating the portion indicated by arrow 7 in FIG. 4 (first embodiment).
- FIG. 8 is a sectional view taken along line 8 - 8 in FIG. 7 (first embodiment).
- FIG. 9 is a sectional view taken along line 9 - 9 in FIG. 5 (first embodiment).
- FIGS. 10 ( a ) and 10 ( b ) are main part vertical perspective views illustrating the state in which movement of a screw shaft is restricted by a movement restricting portion when a nut is rotated to the side loosening the brake cable and the state after that, respectively (first embodiment).
- FIG. 11 illustrates the generation of a twisting force in the brake cable
- FIG. 11 ( a ) is a side view illustrating the brake cable
- FIG. 11 ( b ) is a sectional view taken along line b-b in FIG. 11 ( a ) (first embodiment).
- FIGS. 1 to 11 An embodiment of the invention will be described with reference to attached FIGS. 1 to 11 .
- a drum brake device 11 is provided in, for example, the left-rear wheel of a four-wheel vehicle and this drum brake device 11 includes a fixed back plate 13 having, at the center thereof, a through-hole 12 that passes through a wheel shaft 10 of the left rear wheel, first and second brake shoes 15 and 16 disposed in the back plate 13 so as to enable sliding contact with the inner periphery of a brake drum 14 that rotates together with the left rear wheel, a wheel cylinder 17 fixed to an upper portion of the back plate 13 so as to generate a force for operating the first and second brake shoes 15 and 16 in an expanded manner, a braking clearance automatic adjustment means (so-called automatic adjuster) 18 that automatically adjusts the clearance between the first and second brake shoes 15 and 16 and the brake drum 14 , and a return spring 19 provided between the first and second brake shoes 15 and 16 .
- automatic adjuster braking clearance automatic adjustment means
- the first and second brake shoes 15 and 16 include webs 15 a and 16 a formed in bows along the inner periphery of the brake drum 14 , rims 15 b and 16 b provided in a linked manner orthogonally to the outer peripheries of the webs 15 a and 16 a , and linings 15 c and 16 c pasted to the outer peripheries of the rims 15 b and 16 b.
- the outer end portions of a pair of pistons 20 of the wheel cylinder 17 are disposed so as to face the webs 15 a and 16 a in the upper end portions of the first and second brake shoes 15 and 16 .
- an anchor block 21 that functions as the fulcrum when the first and second brake shoes 15 and 16 are expanded or contracted is provided in a fixed manner in the lower portion of the back plate 13 so as to support one end portions (lower end portions in this embodiment) of the first and second brake shoes 15 and 16 , and the wheel cylinder 17 is operated by the output hydraulic pressure of the master cylinder (not illustrated) operated by the brake pedal and generates a force for driving the first and second brake shoes 15 and 16 in an expanded manner using the anchor block 21 as the fulcrum.
- a coil spring 22 for biasing the lower end portions of the webs 15 a and 16 a of the first and second brake shoes 15 and 16 toward the anchor block 21 is provided between the lower end portions of the webs 15 a and 16 a and the return spring 19 for biasing the first and second brake shoes 15 and 16 in a contraction direction is provided between the upper end portions of the webs 15 a and 16 a of the first and second brake shoes 15 and 16 .
- the braking clearance automatic adjustment means 18 includes a contraction position restricting strut 24 that is provided between the webs 15 a and 16 a of the first and second brake shoes 15 and 16 and stretchable by rotation of an adjustment gear 23 , an adjustment lever 25 that has a feeding claw 25 a to be engaged with the adjustment gear 23 and is pivotably supported by the web 16 a of the second brake shoe 16 , which is one of the first and second brake shoes 15 and 16 , and an adjustment spring 26 that pivotally biases the adjustment lever 25 to the side rotating the adjustment gear 23 in the direction in which the contraction position restricting strut 24 is stretched.
- the contraction position restricting strut 24 restricts the contraction positions of the first and second brake shoes 15 and 16 and includes a first rod 27 that has a first engagement portion 27 a to be engaged with an upper portion of the web 15 a of the first brake shoe 15 of the first and second brake shoes 15 and 16 , a second rod 28 that has a second engagement portion 28 a to be engaged with an upper portion of the web 16 a of the second brake shoe 16 and is disposed concentrically with the first rod 27 , and an adjustment bolt 29 with one end portion inserted into the first rod 27 relatively movably in the axial direction and the other end portion to be screwed concentrically with the second rod 28 , in which the adjustment gear 23 is disposed between the first and second rods 27 and 28 and formed in the outer periphery of the adjustment bolt 29 .
- a first retaining recess 30 with which the first engagement portion 27 a is engaged is provided in the upper portion of the web 15 a of the first brake shoe 15 and a second retaining recess 31 with which the second engagement portion 28 a is engaged is provided in the upper portion of the web 16 a of the second brake shoe 16 .
- the adjustment lever 25 having the feeding claw 25 a to be engaged with the adjustment gear 23 is pivotably supported by the web 16 a of the second brake shoe 16 via a support shaft 32 and the adjustment spring 26 is provided between the web 16 a of the second brake shoe 16 and the adjustment lever 25 . Furthermore, the spring force of the adjustment spring 26 is set smaller than the spring force of the return spring 19 .
- the adjustment lever 25 is pivoted about the axial line of the support shaft 32 by the spring force of the adjustment spring 26 and the adjustment gear 23 is thereby rotated, and the effective length of the contraction position restricting strut 24 is corrected to a larger value.
- the drum brake device 11 is provided with a parking brake lever 34 having one end pivotably supported by the web 15 a of the first brake shoe 15 of the first and second brake shoes 15 and 16 and engaged with one end portion of the contraction position restricting strut 24 .
- the parking brake lever 34 extends upward and downward so as to partially overlap with the web 15 a of the first brake shoe 15 in front view and the upper end portion of this parking brake lever 34 is connected to the upper portion of the web 15 a of the first brake shoe 15 via a pin 35 , and the first engagement portion 27 a of the contraction position restricting strut 24 is engaged with the upper portion of this parking brake lever 34 .
- the parking brake lever 34 When the parking brake of the vehicle is operated, the parking brake lever 34 is driven pivotally counterclockwise about the pin 35 as the fulcrum and this pivot of the parking brake lever 34 causes a force for pressing the lining 16 c of the brake shoe 16 against the inner periphery of the brake drum 14 to act on the second brake shoe 16 via the contraction position restricting strut 24 .
- the parking brake lever 34 is continuously driven pivotally counterclockwise in FIG.
- the parking brake lever 34 is pivoted about the engagement point with respect to the first engagement portion 27 a of the contraction position restricting strut 24 as the fulcrum, the first brake shoe 15 is operated in an expanded manner via the pin 35 and the lining 15 c of the first brake shoe 15 is pressed against the inner periphery of the brake drum 14 . That is, the parking brake lever 34 is operated at an operation position at which the linings 15 c and 16 c of the first and second brake shoes 15 and 16 are pressed against the inner periphery of the brake drum 14 and the parking brake state is obtained in this state.
- the parking brake lever 34 When application of a rotational driving force to the parking brake lever 34 is stopped, the parking brake lever 34 is returned to a non-operation position together with the first and second brake shoes 15 and 16 operated in a direction away from the inner periphery of the brake drum 14 by the spring force of the return spring 19 and the parking brake lever 34 is biased toward the non-operation position.
- the parking brake lever 34 is pivotally driven by the power generated by an electric actuator 36 , the brake cable 37 pulled or loosened by the electric actuator 36 enables the parking brake state to be obtained by pivotally driving the parking brake lever 34 so as to press the contraction position restricting strut 24 against the web 15 a of the second brake shoe 15 by pulling the brake cable 37 and enables the parking brake state to be released by loosening the brake cable 37 , and the brake cable 37 is connected to a lower portion of the parking brake lever 34 .
- the electric actuator 36 includes a screw shaft 38 that is connected to the brake cable 37 , an actuator case 39 that supports the screw shaft 38 movably in the axial direction thereof, an electric motor 40 that is supported by the actuator case 39 rotatably forward and backward, and a motion conversion mechanism 41 that enables conversion from a rotational motion generated by the electric motor 40 to a linear motion of the screw shaft 38 and is accommodated in the actuator case 39 while being interposed between the electric motor 40 and the screw shaft 38 , in which switching between the parking brake state reached by pulling the brake cable 37 and the parking brake release state reached by loosening the brake cable 37 is performed by a change in the rotational direction of the electric motor 40 .
- a bottomed joint hole 42 is concentrically provided in the end portion of the screw shaft 38 close to the brake cable 37 and the end portion of the brake cable 37 close to the electric actuator 36 is inserted into the joint hole 42 . Furthermore, an annular groove 43 is formed in the outer periphery of the screw shaft 38 close to the opening end of the joint hole 42 and the screw shaft 38 is connected to the brake cable 37 by swaging the annular groove 43 so that a part of the screw shaft 38 digs into the brake cable 37 in the state in which the brake cable 37 is inserted into the joint hole 42 .
- the brake cable 37 is drawn into the back plate 13 from the electric actuator 36 mounted to the back plate 13 and an engagement piece 44 fixed to the other end portion of this brake cable 37 is engaged with the lower end portion of the parking brake lever 34 .
- the electric actuator 36 switches between the state in which the screw shaft 38 is moved to the side pulling the brake cable 37 to drive the parking brake lever 34 toward the operation position as illustrated in FIG. 5 and the state in which the screw shaft 38 is moved so as to loosen the brake cable 37 to return the parking brake lever 34 from the operation position toward the non-operation position as illustrated in FIGS. 2 and 4 by a change in the rotational direction of the electric motor 40 .
- a cable guide 51 that sandwiches the anchor block 21 between the cable guide 51 and the lower portion of the back plate 13 is mounted the back plate 13 together with the anchor block 21 via a pair of rivets 52 .
- this cable guide 51 is provided integrally with a guide portion 51 a for guiding the brake cable 37 so as to have a substantially U-shaped cross section.
- the actuator case 39 includes a case main body 47 integrally having first and second accommodating cylindrical portions 45 and 46 , a first cover member 48 coupled to the opening end of the first accommodating cylindrical portion and a second cover member 49 coupled to the case main body 47 from the opposite side of the first cover member 48 .
- the first accommodating cylindrical portion 45 is formed in a bottomed cylinder so as to have a support wall portion 45 a on one end side thereof and a fitting hole 50 is concentrically formed at the center of the support wall portion 45 a .
- the second accommodating cylindrical portion 46 is disposed to the side of the first accommodating cylindrical portion 45 and formed in a bottomed cylinder in which one end portion is open and the other end portion is closed by an end wall portion 46 a disposed in an intermediate part in the longitudinal direction of the first accommodating cylindrical portion 45 , and a cylindrical support cylindrical portion 46 b passing through the screw shaft 38 is provided integrally in a projecting manner at the center of the end wall portion 46 a.
- a cylindrical first bearing portion 53 a that rotatably supports a motor shaft 54 is provided in a projecting manner in one end portion in the axial direction of a motor case 53 of the electric motor 40 , the one end portion of the motor shaft 54 passes through the first bearing portion 53 a and projects from one end portion of the motor case 53 , and a bottomed-cylindrical second bearing portion 53 b that rotatably supports the other end portion of the motor shaft 54 is provided in a projecting manner in the other end portion in the axial direction of the motor case 53 .
- This electric motor 40 is accommodated in the first accommodating cylindrical portion 45 so that the one end portion of the motor case 53 abuts against the support wall portion 45 a while the first bearing portion 53 a is fitted to the fitting hole 50 of the case main body 47 , and the electric motor 40 is accommodated in the first accommodating cylindrical portion 45 while a part (the other end portion of the motor case 53 in which the second bearing portion 53 b is provided in the embodiment) of the electric motor 40 faces the outside.
- the first cover member 48 integrally has a lid portion 48 a that covers the part of the electric motor 40 accommodated in the first accommodating cylindrical portion 45 that faces the outside from the first accommodating cylindrical portion 45 and is coupled to the opening end of the first accommodating cylindrical portion 45 and a connector portion 48 b that overhands toward the side from the lid portion 48 a so that a terminal 55 (see FIG. 3 ) continuous to the electric motor 40 is provided and is disposed to the side of the first accommodating cylindrical portion 45 , and a wave washer 56 is interposed between the second bearing portion 53 b and the lid portion 48 a of the electric motor 40 .
- the lid portion 48 a is formed in a dish shape opened toward the first accommodating cylindrical portion 45 and an annular recess 58 concentric with the first accommodating cylindrical portion 45 having a circular cross section is formed at the open end of this lid portion 48 a .
- an annular fitting projection portion 59 to be fitted to the annular recess 58 is provided in a projecting manner in the opening end portion of the first accommodating cylindrical portion 45 .
- the lid portion 48 a and the first accommodating cylindrical portion 45 are bonded to each other in the state in which the fitting projection portion 59 is fitted to the annular recess 58 .
- the second cover member 49 is coupled to the case main body 47 via bonding or welding so as to form a gear chamber 60 between the second cover member 49 and the case main body 47 .
- the motion conversion mechanism 41 has a nut 61 to be screwed onto the screw shaft 38 as one component and is accommodated in the gear chamber 60 .
- the motion conversion mechanism 41 includes a driving gear 62 provided in the motor shaft 54 of the electric motor 40 , an intermediate large-diameter gear 63 to be meshed with the driving gear 62 , an intermediate small-diameter gear 64 that rotates together with the intermediate large-diameter gear 63 , a driven gear 65 that is meshed with this intermediate small-diameter gear, and the nut 61 to be connected to this driven gear 65 that enables the relative movement in the axial direction of the driven gear 65 and disables the relative rotation about the axial line, and the nut 61 is screwed onto the screw shaft 38 .
- the intermediate large-diameter gear 63 and the intermediate small-diameter gear 64 are formed integrally with each other and are rotatably supported by a support shaft 66 arranged in parallel with the motor shaft 54 and the screw shaft 38 .
- the nut 61 is formed to include a large-diameter cylindrical portion 61 a rotatably accommodated in the second accommodating cylindrical portion 46 , an inward collar portion 61 b that overhangs radially inward from the end portion of the large-diameter cylindrical portion 61 a on the opposite side of the second cover member 49 , and a small-diameter cylindrical portion 61 c that is continuous to the inner peripheral edge of this inward collar portion 61 b , extends toward the opposite side of the second cover member 49 , and passes through the screw shaft 38 .
- Female threads 67 to be screwed onto the screw shaft 38 are engraved in the inner periphery of the small-diameter cylindrical portion 61 c .
- a ball bearing 68 is interposed between the small-diameter cylindrical portion 61 c and the end portion of the second accommodating cylindrical portion 46 close to the end wall portion 46 a .
- An outer race 68 a of this ball bearing 68 is press-fitted to the second accommodating cylindrical portion 46 and the small-diameter cylindrical portion 61 c of the nut 61 is inserted into an inner race 68 b of the ball bearing 68 movably in the axial direction.
- annular projection portion 70 projecting radially outward is provided integrally in a projecting manner in the intermediate portion in the longitudinal direction of the outer periphery of the large-diameter cylindrical portion 61 a , and slits 71 extending in the axial direction are formed so as to cut the annular projection portion 70 at a plurality of positions (for example, four positions) spaced in the circumferential direction of this annular projection portion 70 .
- guide projection portions 72 extending long in the axial direction are provided integrally in a projecting manner so as to project radially inward at a plurality of positions corresponding to the slits 71 in the inner periphery of the driven gear 65 and the guide projection portions 72 are slidably fitted to the slits 71 . That is, the driven gear 65 is fitted onto the outer periphery of the large-diameter cylindrical portion 61 a of the nut 61 while enabling relative movement in the axial direction and disabling relative rotation about the axial line.
- the second cover member 49 of the actuator case 39 is formed by integrally providing, in a linked manner, a cover plate portion 49 a coupled to the case main body 47 so as to cover the gear chamber 60 and a bottomed cylindrical portion 49 b projecting from the cover plate portion 49 a so as to surround the screw shaft 38 and a guide cylindrical portion 74 a integrally owned by an insertion member 74 accommodated and fixed in the actuator case 39 is fitted to the cylindrical portion 49 b.
- the guide cylindrical portion 74 a is formed to include a cylindrical part 74 aa and a plurality of overhang parts 74 ab overhanging radially from the cylindrical part 74 aa and the pair of overhang parts 74 ab is disposed in one diameter line of the cylindrical part 74 aa in the embodiment.
- the overhang part 74 ab forms rotation restricting grooves 75 extending along the axial line of the cylindrical part 74 aa .
- the cylindrical portion 49 b of this second cover member 49 is formed to have an inner surface shape corresponding to the outer surface shape of the guide cylindrical portion 74 a.
- the insertion member 74 is integrally provided with an extended cylindrical portion 74 b that is continuous to the guide cylindrical portion 74 a and enters the gear chamber 60 , a plurality of (for example, two) mount arm portions 74 c that overhang outward to the side from the end portion of the guide cylindrical portion 74 a close to the gear chamber 60 along the inner surface of the cover plate portion 49 a of the second cover member 49 , and one support arm portion 74 d that overhands outward to the side from the end portion of the guide cylindrical portion 74 a close to the gear chamber 60 along the inner surface of the cover plate portion 49 a.
- a positioning projection portion 74 e projecting toward the second accommodating cylindrical portion 46 is provided integrally in a projecting manner in a front end portion of the mount arm portion 74 c and the insertion member 74 is accommodated and fixed in the actuator case 39 by sandwiching the front end portion of the mount arm portion 74 c and the positioning projection portion 74 e between the second accommodating cylindrical portion 46 and the cover plate portion 49 a of the second cover member 49 .
- both end portions of the support shaft 66 for rotatably supporting the intermediate large-diameter gear 63 and the intermediate small-diameter gear 64 are supported between the front end portion of the support arm portion 74 d and the support wall portion 45 a of the first accommodating cylindrical portion 45 .
- a rotation restricting means 73 for restricting the rotation of the screw shaft 38 is provided between the guide cylindrical portion 74 a of the insertion member 74 and the screw shaft 38 and this rotation restricting means 73 includes a plurality of (two in the embodiment) rotation restricting projection portions 76 b that are provided in the end portion of the screw shaft 38 on the opposite side of the brake cable 37 and radially project from the screw shaft 38 and the plurality of (two in the embodiment) rotation restricting grooves 75 that are formed in the guide cylindrical portion 74 a so as to be entered by the rotation restricting projection portions 76 b.
- a cap 76 is put on the end portion of the screw shaft 38 on the opposite side of the brake cable 37 .
- This cap 76 is formed by integrally providing a bottomed cylindrical portion 76 a to which the end portion of the screw shaft 38 is fitted and the plurality of the rotation restricting projection portions 76 b radially projecting from the bottomed cylindrical portion 76 a so as to be inserted into the rotation restricting grooves 75 of the guide cylindrical portion 74 a of the insertion member 74 and, in the embodiment, the pair of rotation restricting projection portions 76 b projects radially outward from the bottomed cylindrical portion 76 a along the one diameter line of the bottomed cylindrical portion 76 a .
- the cap 76 is fixed to the screw shaft 38 via a pin 77 that passes through the screw shaft 38 and the bottomed cylindrical portion 76 a along the one diameter line.
- This provides the pair of rotation restricting projection portions 76 b in the end portion of the screw shaft 38 on the opposite side of the brake cable 37 , causes the rotation restricting projection portions 76 b to enter the rotation restricting grooves 75 of the insertion member 74 accommodated and fixed in the actuator case 39 , and makes the screw shaft 38 movable in a direction along the axial line while being prevented from rotating about the axial line.
- the movement end of the screw shaft 38 in movement in the direction loosening the brake cable 37 is restricted by causing the cap 76 to abut against a movement restricting portion 74 f accommodated and fixed in the actuator case 39 and, in the embodiment, the movement restricting portion 74 f is integrally provided at the front end of the extended cylindrical portion 74 b of the insertion member 74 . That is, the movement restricting portion 74 f is integrally provided in the front end portion of the extended cylindrical portion 74 b so as to overhang radially inward from the front end portion of the extended cylindrical portion 74 b.
- the nut 61 is provided with a recess 81 defined by the large-diameter cylindrical portion 61 a and the inward collar portion 61 b of the nut 61 so that the recess 81 is opened toward the insertion member 74 , and the disc springs 80 are accommodated in the recess 81 .
- the plurality of disc springs 80 and a disc-shaped retainer 82 that sandwiches these disc springs 80 between the disc-shaped retainer 82 and the inward collar portion 61 b of the nut 61 are accommodated in the recess 81 .
- the nut 61 is provided with a holding member 83 for preventing the disc springs 80 and the retainer 82 from being removed from the recess 81 on the opening end side of the recess 80 , this holding member 83 is formed to integrally have a ring plate portion 83 a that abuts against the end portion of the large-diameter cylindrical portion 61 a of the nut 61 close to the insertion member 74 and a short cylindrical portion 83 b that is continuous to the inner periphery of this ring plate portion 83 a and press-fitted to the large-diameter cylindrical portion 61 a of the nut 61 , the inner diameter of the short cylindrical portion 83 b is set larger than the outer diameter of the movement restricting
- the retainer 82 abuts against the movement restricting portion 74 f of the insertion member 74 in response to the movement in the axial direction of the nut 61 , the disc springs 80 are compressed between the nut 61 and the movement restricting portion 74 f , thereby enabling an increase in the load on the electric motor 40 .
- a mount cylindrical portion 85 extending backward and inward in the vehicle width direction is provided integrally in a projecting manner on the back plate 13 of the drum brake device 11 .
- This mount cylindrical portion 85 is provided with a large-diameter cylindrical portion 85 a with one end that is open backward and inward in the vehicle width direction and a small-diameter cylindrical portion 85 c that is concentrically continuous to the large-diameter cylindrical portion 85 a with a step portion 85 b provided between the small-diameter cylindrical portion 85 c and the other end of the large-diameter cylindrical portion 85 a .
- the actuator case 39 is mounted to the mount cylindrical portion by inserting the second accommodating cylindrical portion 46 of the first cover member 48 in the actuator case 39 of the electric actuator 36 into the large-diameter cylindrical portion 85 a and engaging a C-shaped locking ring 88 mounted to the outer periphery of the second accommodating cylindrical portion 46 with a locking groove 87 formed in the inner periphery of the large-diameter cylindrical portion 85 a.
- the actuator case 39 When the actuator case 39 is mounted to the mount cylindrical portion 85 of the back plate 13 as described above, the actuator case 39 is mounted to the rear side in the front-rear direction of the vehicle of the back plate 13 and the connector portion 48 b is oriented to the rear side in the front-rear direction of the vehicle.
- a bellows boot 89 for covering a projection portion of the screw shaft 38 from the second accommodating cylindrical portion 46 is provided between the outer periphery of the support cylindrical portion 46 b of the second accommodating cylindrical portion 46 and the outer periphery of one end portion of the screw shaft 38 .
- the brake cable 37 is a bunch of a plurality of twisted wires 92 and generates a twisting force in the direction indicated by arrow 91 in FIGS. 11 ( a ) and 11 ( b ) when pulled in the direction indicated by arrow 90 in FIG. 11 ( a ) to obtain the parking brake state.
- a setting is made so that the direction in which the twisting force in this case acts on the screw shaft 38 is the same as the rotational direction of the nut 61 when the electric motor 40 operates in the direction loosening the brake cable 37 for switching from the parking brake state to the parking brake release state.
- the nut 61 of the motion conversion mechanism 41 capable of converting a rotational motion generated by the electric motor 40 to a linear motion of the screw shaft 38 connected to the brake cable 37 is screwed onto the screw shaft 38 movably in the axial direction within a restricted range in a direction along the axial line of the screw shaft 38 , the movement restricting portion 74 f that restricts the movement end in the axial direction of the screw shaft 38 in movement to the side loosening the brake cable 37 to reach the parking brake release state is provided in a fixed position in the actuator case 39 , and the disc springs 80 , which are resilient members, are interposed between the nut 61 and the insertion member 74 accommodated and fixed in the actuator case 39 so as to be compressed in response to movement of the nut 61 in the axial direction after the cap 76 fixed to the screw shaft 38 abuts against the movement restricting portion 74 f when the screw shaft 38 moves in the axial direction to the side loosening the brake cable 37 ,
- the electric motor 40 can be controlled appropriately and the members constituting the motion conversion mechanism 41 can be prevented from shifting to a lock state. Furthermore, since the nut 61 is relatively movable in the axial direction with respect to the screw shaft 38 , generation of an operating sound in parking brake release operation can be prevented. In addition, since the disc springs 80 are provided between the insertion member 74 accommodated and fixed in the actuator case 39 and the nut 61 , the strength of the actuator case 39 does not need to be increased more than necessity.
- the internal structure of the actuator case 39 can be simplified while suppressing an increase in the number of components by providing the disc springs 80 between the nut 61 and the movement restricting portion 74 f provided integrally with the insertion member 74 .
- the resilient members are the disc springs 80 , the space that needs to be reserved in the actuator case 39 to dispose the disc springs 80 can be reduced and the actuator case 39 can be small-sized.
- the brake cable 37 is formed by twisting the plurality of wires 92 so as to generate a twisting force when pulled and the direction in which the twisting force acts on the screw shaft 38 is the same as the rotational direction of the nut 61 when the brake cable 37 is loosened, even if the nut 61 is rotated so as to obtain the parking brake state, the screw shaft 38 is rotated and reaches a rotary position A indicated by the dotted line in FIG.
- the rotation restricting projection portions 76 b are returned to the vicinity of a rotary position B indicated by the dotted line in FIG. 9 by the twisting force from the brake cable 37 when the parking brake state is maintained. Even when the rotation restricting projection portions 76 b of the cap 76 reach the rotary position B by the backward rotation of the nut 61 during switching from the parking brake state to the parking brake release state and make contact with the side surface of the rotation restricting grooves 75 of the insertion member 74 , it is possible to prevent the cap 76 and the insertion member 74 from strongly colliding with each other, suppress the generation of a slapping sound, and reduce the operating sound.
- the rotation restricting means 73 includes the plurality of rotation restricting projection portions 76 b that are provided in the end portion of the screw shaft 38 opposite to the brake cable 37 and radially project from the screw shaft 38 and the plurality of the rotation restricting grooves 75 formed in the insertion member 74 so as to be entered by the rotation restricting projection portions 76 b , the operating sound can be reduced more effectively by restricting the rotation of the screw shaft 38 at a plurality of positions in the circumferential direction of the screw shaft 38 .
- the insertion member does not need to be accommodated and fixed in the actuator case and the rotation restricting grooves may be formed in the actuator case.
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Transportation (AREA)
- Braking Arrangements (AREA)
- Braking Systems And Boosters (AREA)
- Braking Elements And Transmission Devices (AREA)
Abstract
In an electric parking brake device configured in such a way that a parking brake state resulting from pulling of a brake cable is released by loosening the brake cable, the brake cable is formed by twisting together a plurality of wires and the direction of twisting is rotational direction of the nut when the brake cable is pulled. This makes it possible to reduce an operating sound and to reduce wear of members constituting a rotation restricting device.
Description
- This application is a continuation application of U.S. Ser. No. 17/043,296, filed on Sep. 29, 2020, which is a US National Phase of International Application No. PCT/JP2018/044929 filed on Dec. 6, 2018; and which is based upon and claims the benefit of priority from the prior Japanese Patent Application No. JP 2018-068037, filed on Mar. 30, 2018. The entire contents of each of such prior art applications are incorporated herein by reference.
- The present invention relates to an electric parking brake device including a screw shaft that is connected to a brake cable; an actuator case that supports the screw shaft movably in an axial direction thereof; an electric motor that is supported by the actuator case rotatably forward and backward; a motion conversion mechanism that has a nut to be screwed onto the screw shaft, enables conversion from a rotational motion generated in the electric motor to a linear motion of the screw shaft, and is accommodated in the actuator case; and a rotation restricting means that restricts a rotational motion of the screw shaft, in which switching between a parking brake state reached by pulling the brake cable and a non-parking brake state reached by loosening the brake cable is performed by a change in a rotational direction of the electric motor.
- An electric parking brake device that switches between a state in which a parking brake force is obtained by pulling a brake cable and a state in which a parking brake force is released by loosening the brake cable by a change in the rotational direction of an electric motor is known in
PTL 1. - PTL 1: JP-A-2017-82834
- Although the electric parking brake device disclosed in
PTL 1 has a rotation restricting means, configured by a projection portion provided in the screw shaft and a groove formed in the actuator case so as to be entered by the projection portion, for restricting the rotation of the screw shaft, since a clearance is present between the projection portion and the groove, the projection portion collides with the side surface of the groove and causes a slapping sound when the rotational direction of the screw shaft is changed to switch between the parking brake state and the parking brake release state and may cause a large operating sound. In addition, if the projection portion is kept pressed strongly against the side surface of the groove during movement in the axial direction of the screw shaft when a rotational motion is restricted by the rotation restricting means, the sliding resistance of the projection portion becomes large, thereby increasing wear of the projection portion and the actuator case. - The invention addresses the above situation with an object of providing an electric parking brake device that reduces an operating sound during switching between the parking brake state and the parking brake release state and reduces wear of members constituting the rotation restricting means.
- To achieve the above object, according to a first aspect of the invention, there is provided an electric parking brake device including a screw shaft that is connected to a brake cable; an actuator case that supports the screw shaft movably in an axial direction thereof; an electric motor that is supported by the actuator case rotatably forward and backward; a motion conversion mechanism that has a nut to be screwed onto the screw shaft, enables conversion from a rotational motion generated in the electric motor to a linear motion of the screw shaft, and is accommodated in the actuator case; and a rotation restricting means that restricts a rotational motion of the screw shaft, in which switching between a parking brake state reached by pulling the brake cable and a non-parking brake state reached by loosening the brake cable is performed by a change in a rotational direction of the electric motor, in which the brake cable is formed by twisting a plurality of wires so as to generate a twisting force in a fixed direction when the brake cable is pulled, and a direction in which the twisting force generated by the brake cable in a pulled state acts on the screw shaft is set identical to a rotational direction of the nut when the brake cable is loosened.
- According to a second aspect of the invention, in addition to the structure in the first aspect, the rotation restricting means includes a plurality of rotation restricting projection portions that are provided in an end portion of the screw shaft opposite to the brake cable and radially project from the screw shaft and a plurality of rotation restricting grooves formed in the actuator case or an insertion member accommodated and fixed in the actuator case and entered by the rotation restricting projection portions.
- In the first aspect of the invention, since the twisting force for rotationally biasing the screw shaft to the side loosening the brake cable acts on the screw shaft from the brake cable when the brake cable is pulled, it is possible to prevent components constituting the rotation restricting means from strongly colliding with each other during switching from the parking brake state to the parking brake release state, suppress the generation of a slapping sound, and reduce the operating sound. In addition, when the screw shaft is moved in the axial direction to enter the parking brake state by pulling the brake cable, it is possible to prevent components constituting the rotation restricting means from strongly colliding with each other, reduce the driving torque of the electric motor by reducing the sliding resistance, and reduce wear of members constituting the rotation restricting means.
- In addition, in the second aspect of the invention, the operating sound can be reduced more effectively by restricting the rotation of the screw shaft at a plurality of positions in the circumferential direction of the screw shaft.
-
FIG. 1 is a front view illustrating a drum brake device (first embodiment). -
FIG. 2 is a sectional view taken along line 2-2 inFIG. 1 (first embodiment). -
FIG. 3 is a perspective view seen alongarrow 3 inFIG. 1 (first embodiment). -
FIG. 4 is a sectional view, taken along line 4-4 inFIG. 3 , that illustrates the state in which a brake cable is being loosened (first embodiment). -
FIG. 5 is a sectional view, corresponding toFIG. 4 , that illustrates the state in which the brake cable has been pulled (first embodiment). -
FIG. 6 is a perspective view illustrating an electric actuator (first embodiment). -
FIG. 7 is an enlarged view illustrating the portion indicated by arrow 7 inFIG. 4 (first embodiment). -
FIG. 8 is a sectional view taken along line 8-8 inFIG. 7 (first embodiment). -
FIG. 9 is a sectional view taken along line 9-9 inFIG. 5 (first embodiment). -
FIGS. 10(a) and 10(b) are main part vertical perspective views illustrating the state in which movement of a screw shaft is restricted by a movement restricting portion when a nut is rotated to the side loosening the brake cable and the state after that, respectively (first embodiment). -
FIG. 11 illustrates the generation of a twisting force in the brake cable,FIG. 11(a) is a side view illustrating the brake cable, andFIG. 11(b) is a sectional view taken along line b-b inFIG. 11(a) (first embodiment). -
-
- 37: brake cable
- 38: screw shaft
- 39: actuator case
- 40: electric motor
- 41: motion conversion mechanism
- 61: nut
- 73: rotation restricting means
- 74: insertion member
- 75: rotation restricting groove
- 76 b: rotation restricting projection portion
- 92: wire
- An embodiment of the invention will be described with reference to attached
FIGS. 1 to 11 . - In
FIGS. 1 to 3 , adrum brake device 11 is provided in, for example, the left-rear wheel of a four-wheel vehicle and thisdrum brake device 11 includes a fixedback plate 13 having, at the center thereof, a through-hole 12 that passes through awheel shaft 10 of the left rear wheel, first andsecond brake shoes back plate 13 so as to enable sliding contact with the inner periphery of abrake drum 14 that rotates together with the left rear wheel, awheel cylinder 17 fixed to an upper portion of theback plate 13 so as to generate a force for operating the first andsecond brake shoes second brake shoes brake drum 14, and areturn spring 19 provided between the first andsecond brake shoes - The first and
second brake shoes webs brake drum 14,rims webs linings rims - The outer end portions of a pair of
pistons 20 of thewheel cylinder 17 are disposed so as to face thewebs second brake shoes anchor block 21 that functions as the fulcrum when the first andsecond brake shoes back plate 13 so as to support one end portions (lower end portions in this embodiment) of the first andsecond brake shoes wheel cylinder 17 is operated by the output hydraulic pressure of the master cylinder (not illustrated) operated by the brake pedal and generates a force for driving the first andsecond brake shoes anchor block 21 as the fulcrum. - A
coil spring 22 for biasing the lower end portions of thewebs second brake shoes anchor block 21 is provided between the lower end portions of thewebs return spring 19 for biasing the first andsecond brake shoes webs second brake shoes - The braking clearance automatic adjustment means 18 includes a contraction
position restricting strut 24 that is provided between thewebs second brake shoes adjustment gear 23, anadjustment lever 25 that has afeeding claw 25 a to be engaged with theadjustment gear 23 and is pivotably supported by theweb 16 a of thesecond brake shoe 16, which is one of the first andsecond brake shoes adjustment spring 26 that pivotally biases theadjustment lever 25 to the side rotating theadjustment gear 23 in the direction in which the contractionposition restricting strut 24 is stretched. - The contraction
position restricting strut 24 restricts the contraction positions of the first andsecond brake shoes first rod 27 that has afirst engagement portion 27 a to be engaged with an upper portion of theweb 15 a of thefirst brake shoe 15 of the first andsecond brake shoes second rod 28 that has asecond engagement portion 28 a to be engaged with an upper portion of theweb 16 a of thesecond brake shoe 16 and is disposed concentrically with thefirst rod 27, and anadjustment bolt 29 with one end portion inserted into thefirst rod 27 relatively movably in the axial direction and the other end portion to be screwed concentrically with thesecond rod 28, in which theadjustment gear 23 is disposed between the first andsecond rods adjustment bolt 29. - A first retaining recess 30 with which the
first engagement portion 27 a is engaged is provided in the upper portion of theweb 15 a of thefirst brake shoe 15 and asecond retaining recess 31 with which thesecond engagement portion 28 a is engaged is provided in the upper portion of theweb 16 a of thesecond brake shoe 16. - The
adjustment lever 25 having thefeeding claw 25 a to be engaged with theadjustment gear 23 is pivotably supported by theweb 16 a of thesecond brake shoe 16 via asupport shaft 32 and theadjustment spring 26 is provided between theweb 16 a of thesecond brake shoe 16 and theadjustment lever 25. Furthermore, the spring force of theadjustment spring 26 is set smaller than the spring force of thereturn spring 19. - In the braking clearance automatic adjustment means 18 described above, if the first and
second brake shoes linings second brake shoes wheel cylinder 17, theadjustment lever 25 is pivoted about the axial line of thesupport shaft 32 by the spring force of theadjustment spring 26 and theadjustment gear 23 is thereby rotated, and the effective length of the contractionposition restricting strut 24 is corrected to a larger value. - By the way, the
drum brake device 11 is provided with aparking brake lever 34 having one end pivotably supported by theweb 15 a of thefirst brake shoe 15 of the first andsecond brake shoes position restricting strut 24. - The
parking brake lever 34 extends upward and downward so as to partially overlap with theweb 15 a of thefirst brake shoe 15 in front view and the upper end portion of thisparking brake lever 34 is connected to the upper portion of theweb 15 a of thefirst brake shoe 15 via apin 35, and thefirst engagement portion 27 a of the contractionposition restricting strut 24 is engaged with the upper portion of thisparking brake lever 34. - When the parking brake of the vehicle is operated, the
parking brake lever 34 is driven pivotally counterclockwise about thepin 35 as the fulcrum and this pivot of theparking brake lever 34 causes a force for pressing thelining 16 c of thebrake shoe 16 against the inner periphery of thebrake drum 14 to act on thesecond brake shoe 16 via the contractionposition restricting strut 24. In addition, when theparking brake lever 34 is continuously driven pivotally counterclockwise inFIG. 1 , theparking brake lever 34 is pivoted about the engagement point with respect to thefirst engagement portion 27 a of the contractionposition restricting strut 24 as the fulcrum, thefirst brake shoe 15 is operated in an expanded manner via thepin 35 and thelining 15 c of thefirst brake shoe 15 is pressed against the inner periphery of thebrake drum 14. That is, theparking brake lever 34 is operated at an operation position at which thelinings second brake shoes brake drum 14 and the parking brake state is obtained in this state. - When application of a rotational driving force to the
parking brake lever 34 is stopped, theparking brake lever 34 is returned to a non-operation position together with the first andsecond brake shoes brake drum 14 by the spring force of thereturn spring 19 and theparking brake lever 34 is biased toward the non-operation position. - The
parking brake lever 34 is pivotally driven by the power generated by anelectric actuator 36, thebrake cable 37 pulled or loosened by theelectric actuator 36 enables the parking brake state to be obtained by pivotally driving theparking brake lever 34 so as to press the contractionposition restricting strut 24 against theweb 15 a of thesecond brake shoe 15 by pulling thebrake cable 37 and enables the parking brake state to be released by loosening thebrake cable 37, and thebrake cable 37 is connected to a lower portion of theparking brake lever 34. - Referring to
FIGS. 4 and 5 together, theelectric actuator 36 includes ascrew shaft 38 that is connected to thebrake cable 37, anactuator case 39 that supports thescrew shaft 38 movably in the axial direction thereof, anelectric motor 40 that is supported by theactuator case 39 rotatably forward and backward, and amotion conversion mechanism 41 that enables conversion from a rotational motion generated by theelectric motor 40 to a linear motion of thescrew shaft 38 and is accommodated in theactuator case 39 while being interposed between theelectric motor 40 and thescrew shaft 38, in which switching between the parking brake state reached by pulling thebrake cable 37 and the parking brake release state reached by loosening thebrake cable 37 is performed by a change in the rotational direction of theelectric motor 40. - A bottomed
joint hole 42 is concentrically provided in the end portion of thescrew shaft 38 close to thebrake cable 37 and the end portion of thebrake cable 37 close to theelectric actuator 36 is inserted into thejoint hole 42. Furthermore, anannular groove 43 is formed in the outer periphery of thescrew shaft 38 close to the opening end of thejoint hole 42 and thescrew shaft 38 is connected to thebrake cable 37 by swaging theannular groove 43 so that a part of thescrew shaft 38 digs into thebrake cable 37 in the state in which thebrake cable 37 is inserted into thejoint hole 42. - The
brake cable 37 is drawn into theback plate 13 from theelectric actuator 36 mounted to theback plate 13 and anengagement piece 44 fixed to the other end portion of thisbrake cable 37 is engaged with the lower end portion of theparking brake lever 34. - The
electric actuator 36 switches between the state in which thescrew shaft 38 is moved to the side pulling thebrake cable 37 to drive theparking brake lever 34 toward the operation position as illustrated inFIG. 5 and the state in which thescrew shaft 38 is moved so as to loosen thebrake cable 37 to return theparking brake lever 34 from the operation position toward the non-operation position as illustrated inFIGS. 2 and 4 by a change in the rotational direction of theelectric motor 40. - In the lower portion of the
back plate 13, acable guide 51 that sandwiches theanchor block 21 between thecable guide 51 and the lower portion of theback plate 13 is mounted theback plate 13 together with theanchor block 21 via a pair ofrivets 52. As clearly illustrated inFIG. 2 , thiscable guide 51 is provided integrally with aguide portion 51 a for guiding thebrake cable 37 so as to have a substantially U-shaped cross section. - Referring to
FIG. 6 together, theactuator case 39 includes a casemain body 47 integrally having first and second accommodatingcylindrical portions first cover member 48 coupled to the opening end of the first accommodating cylindrical portion and asecond cover member 49 coupled to the casemain body 47 from the opposite side of thefirst cover member 48. - The first accommodating
cylindrical portion 45 is formed in a bottomed cylinder so as to have asupport wall portion 45 a on one end side thereof and afitting hole 50 is concentrically formed at the center of thesupport wall portion 45 a. The second accommodatingcylindrical portion 46 is disposed to the side of the first accommodatingcylindrical portion 45 and formed in a bottomed cylinder in which one end portion is open and the other end portion is closed by anend wall portion 46 a disposed in an intermediate part in the longitudinal direction of the first accommodatingcylindrical portion 45, and a cylindrical supportcylindrical portion 46 b passing through thescrew shaft 38 is provided integrally in a projecting manner at the center of theend wall portion 46 a. - A cylindrical
first bearing portion 53 a that rotatably supports amotor shaft 54 is provided in a projecting manner in one end portion in the axial direction of amotor case 53 of theelectric motor 40, the one end portion of themotor shaft 54 passes through thefirst bearing portion 53 a and projects from one end portion of themotor case 53, and a bottomed-cylindricalsecond bearing portion 53 b that rotatably supports the other end portion of themotor shaft 54 is provided in a projecting manner in the other end portion in the axial direction of themotor case 53. - This
electric motor 40 is accommodated in the first accommodatingcylindrical portion 45 so that the one end portion of themotor case 53 abuts against thesupport wall portion 45 a while thefirst bearing portion 53 a is fitted to thefitting hole 50 of the casemain body 47, and theelectric motor 40 is accommodated in the first accommodatingcylindrical portion 45 while a part (the other end portion of themotor case 53 in which thesecond bearing portion 53 b is provided in the embodiment) of theelectric motor 40 faces the outside. - The
first cover member 48 integrally has alid portion 48 a that covers the part of theelectric motor 40 accommodated in the first accommodatingcylindrical portion 45 that faces the outside from the first accommodatingcylindrical portion 45 and is coupled to the opening end of the first accommodatingcylindrical portion 45 and aconnector portion 48 b that overhands toward the side from thelid portion 48 a so that a terminal 55 (seeFIG. 3 ) continuous to theelectric motor 40 is provided and is disposed to the side of the first accommodatingcylindrical portion 45, and awave washer 56 is interposed between thesecond bearing portion 53 b and thelid portion 48 a of theelectric motor 40. - The
lid portion 48 a is formed in a dish shape opened toward the first accommodatingcylindrical portion 45 and anannular recess 58 concentric with the first accommodatingcylindrical portion 45 having a circular cross section is formed at the open end of thislid portion 48 a. In contrast, an annularfitting projection portion 59 to be fitted to theannular recess 58 is provided in a projecting manner in the opening end portion of the first accommodatingcylindrical portion 45. Thelid portion 48 a and the first accommodatingcylindrical portion 45 are bonded to each other in the state in which thefitting projection portion 59 is fitted to theannular recess 58. This enables the relative position in the circumferential direction of theconnector portion 48 b with respect to the first accommodatingcylindrical portion 45 to be selected at a plurality of positions about the axial line of the first accommodatingcylindrical portion 45, increases the freedom of the position of theconnector portion 48 b with respect to theactuator case 39, and facilitates changes in the orientation of theconnector portion 48 b. - The
second cover member 49 is coupled to the casemain body 47 via bonding or welding so as to form agear chamber 60 between thesecond cover member 49 and the casemain body 47. In addition, themotion conversion mechanism 41 has anut 61 to be screwed onto thescrew shaft 38 as one component and is accommodated in thegear chamber 60. - The
motion conversion mechanism 41 includes adriving gear 62 provided in themotor shaft 54 of theelectric motor 40, an intermediate large-diameter gear 63 to be meshed with thedriving gear 62, an intermediate small-diameter gear 64 that rotates together with the intermediate large-diameter gear 63, a drivengear 65 that is meshed with this intermediate small-diameter gear, and thenut 61 to be connected to this drivengear 65 that enables the relative movement in the axial direction of the drivengear 65 and disables the relative rotation about the axial line, and thenut 61 is screwed onto thescrew shaft 38. In addition, the intermediate large-diameter gear 63 and the intermediate small-diameter gear 64 are formed integrally with each other and are rotatably supported by asupport shaft 66 arranged in parallel with themotor shaft 54 and thescrew shaft 38. - Referring to
FIG. 7 together, thenut 61 is formed to include a large-diametercylindrical portion 61 a rotatably accommodated in the second accommodatingcylindrical portion 46, aninward collar portion 61 b that overhangs radially inward from the end portion of the large-diametercylindrical portion 61 a on the opposite side of thesecond cover member 49, and a small-diametercylindrical portion 61 c that is continuous to the inner peripheral edge of thisinward collar portion 61 b, extends toward the opposite side of thesecond cover member 49, and passes through thescrew shaft 38. -
Female threads 67 to be screwed onto thescrew shaft 38 are engraved in the inner periphery of the small-diametercylindrical portion 61 c. In addition, aball bearing 68 is interposed between the small-diametercylindrical portion 61 c and the end portion of the second accommodatingcylindrical portion 46 close to theend wall portion 46 a. Anouter race 68 a of thisball bearing 68 is press-fitted to the second accommodatingcylindrical portion 46 and the small-diametercylindrical portion 61 c of thenut 61 is inserted into aninner race 68 b of theball bearing 68 movably in the axial direction. - Referring to
FIG. 8 together, anannular projection portion 70 projecting radially outward is provided integrally in a projecting manner in the intermediate portion in the longitudinal direction of the outer periphery of the large-diametercylindrical portion 61 a, and slits 71 extending in the axial direction are formed so as to cut theannular projection portion 70 at a plurality of positions (for example, four positions) spaced in the circumferential direction of thisannular projection portion 70. On the other hand, guideprojection portions 72 extending long in the axial direction are provided integrally in a projecting manner so as to project radially inward at a plurality of positions corresponding to theslits 71 in the inner periphery of the drivengear 65 and theguide projection portions 72 are slidably fitted to theslits 71. That is, the drivengear 65 is fitted onto the outer periphery of the large-diametercylindrical portion 61 a of thenut 61 while enabling relative movement in the axial direction and disabling relative rotation about the axial line. - Referring to
FIG. 9 together, thesecond cover member 49 of theactuator case 39 is formed by integrally providing, in a linked manner, acover plate portion 49 a coupled to the casemain body 47 so as to cover thegear chamber 60 and a bottomedcylindrical portion 49 b projecting from thecover plate portion 49 a so as to surround thescrew shaft 38 and a guidecylindrical portion 74 a integrally owned by aninsertion member 74 accommodated and fixed in theactuator case 39 is fitted to thecylindrical portion 49 b. - The guide
cylindrical portion 74 a is formed to include acylindrical part 74 aa and a plurality ofoverhang parts 74 ab overhanging radially from thecylindrical part 74 aa and the pair ofoverhang parts 74 ab is disposed in one diameter line of thecylindrical part 74 aa in the embodiment. In addition, theoverhang part 74 ab formsrotation restricting grooves 75 extending along the axial line of thecylindrical part 74 aa. Thecylindrical portion 49 b of thissecond cover member 49 is formed to have an inner surface shape corresponding to the outer surface shape of the guidecylindrical portion 74 a. - The
insertion member 74 is integrally provided with an extendedcylindrical portion 74 b that is continuous to the guidecylindrical portion 74 a and enters thegear chamber 60, a plurality of (for example, two)mount arm portions 74 c that overhang outward to the side from the end portion of the guidecylindrical portion 74 a close to thegear chamber 60 along the inner surface of thecover plate portion 49 a of thesecond cover member 49, and onesupport arm portion 74 d that overhands outward to the side from the end portion of the guidecylindrical portion 74 a close to thegear chamber 60 along the inner surface of thecover plate portion 49 a. - In addition, a
positioning projection portion 74 e projecting toward the second accommodatingcylindrical portion 46 is provided integrally in a projecting manner in a front end portion of themount arm portion 74 c and theinsertion member 74 is accommodated and fixed in theactuator case 39 by sandwiching the front end portion of themount arm portion 74 c and thepositioning projection portion 74 e between the second accommodatingcylindrical portion 46 and thecover plate portion 49 a of thesecond cover member 49. - In addition, both end portions of the
support shaft 66 for rotatably supporting the intermediate large-diameter gear 63 and the intermediate small-diameter gear 64 are supported between the front end portion of thesupport arm portion 74 d and thesupport wall portion 45 a of the first accommodatingcylindrical portion 45. - Focusing on
FIG. 9 , a rotation restricting means 73 for restricting the rotation of thescrew shaft 38 is provided between the guidecylindrical portion 74 a of theinsertion member 74 and thescrew shaft 38 and this rotation restricting means 73 includes a plurality of (two in the embodiment) rotation restrictingprojection portions 76 b that are provided in the end portion of thescrew shaft 38 on the opposite side of thebrake cable 37 and radially project from thescrew shaft 38 and the plurality of (two in the embodiment)rotation restricting grooves 75 that are formed in the guidecylindrical portion 74 a so as to be entered by the rotation restrictingprojection portions 76 b. - A
cap 76 is put on the end portion of thescrew shaft 38 on the opposite side of thebrake cable 37. Thiscap 76 is formed by integrally providing a bottomedcylindrical portion 76 a to which the end portion of thescrew shaft 38 is fitted and the plurality of the rotation restrictingprojection portions 76 b radially projecting from the bottomedcylindrical portion 76 a so as to be inserted into therotation restricting grooves 75 of the guidecylindrical portion 74 a of theinsertion member 74 and, in the embodiment, the pair of rotation restrictingprojection portions 76 b projects radially outward from the bottomedcylindrical portion 76 a along the one diameter line of the bottomedcylindrical portion 76 a. In addition, thecap 76 is fixed to thescrew shaft 38 via apin 77 that passes through thescrew shaft 38 and the bottomedcylindrical portion 76 a along the one diameter line. This provides the pair of rotation restrictingprojection portions 76 b in the end portion of thescrew shaft 38 on the opposite side of thebrake cable 37, causes the rotation restrictingprojection portions 76 b to enter therotation restricting grooves 75 of theinsertion member 74 accommodated and fixed in theactuator case 39, and makes thescrew shaft 38 movable in a direction along the axial line while being prevented from rotating about the axial line. - By the way, when the
brake cable 37 is pulled to drive theparking brake lever 34 toward the operation position, thescrew shaft 38 moves so as to cause thecap 76 to separate from thenut 61 as illustrated inFIG. 5 . When thebrake cable 37 is loosened to return theparking brake lever 34 from the operation position toward the non-operation position, thescrew shaft 38 moves so as to cause thecap 76 to come close to thenut 61 as illustrated inFIG. 4 . The movement end of thescrew shaft 38 in movement in the direction loosening thebrake cable 37 is restricted by causing thecap 76 to abut against amovement restricting portion 74 f accommodated and fixed in theactuator case 39 and, in the embodiment, themovement restricting portion 74 f is integrally provided at the front end of the extendedcylindrical portion 74 b of theinsertion member 74. That is, themovement restricting portion 74 f is integrally provided in the front end portion of the extendedcylindrical portion 74 b so as to overhang radially inward from the front end portion of the extendedcylindrical portion 74 b. - By the way, in the state in which the
cap 76 abuts against themovement restricting portion 74 f as illustrated inFIG. 10(a) and then theelectric motor 40 continues the operation when thescrew shaft 38 moves in the direction loosening thebrake cable 37, thenut 61 that rotates relative to thescrew shaft 38 that has stopped movement in the axial direction moves in the axial direction so as to increase the interval from theball bearing 68 as illustrated inFIG. 10(b) and a plurality of disc springs 80 as resilient members compressed in response to the movement in the axial direction of thenut 61 is disposed between thenut 61 and theinsertion member 74. - The
nut 61 is provided with arecess 81 defined by the large-diametercylindrical portion 61 a and theinward collar portion 61 b of thenut 61 so that therecess 81 is opened toward theinsertion member 74, and the disc springs 80 are accommodated in therecess 81. - The plurality of disc springs 80 and a disc-shaped
retainer 82 that sandwiches these disc springs 80 between the disc-shapedretainer 82 and theinward collar portion 61 b of thenut 61 are accommodated in therecess 81. Thenut 61 is provided with a holdingmember 83 for preventing the disc springs 80 and theretainer 82 from being removed from therecess 81 on the opening end side of therecess 80, this holdingmember 83 is formed to integrally have aring plate portion 83 a that abuts against the end portion of the large-diametercylindrical portion 61 a of thenut 61 close to theinsertion member 74 and a shortcylindrical portion 83 b that is continuous to the inner periphery of thisring plate portion 83 a and press-fitted to the large-diametercylindrical portion 61 a of thenut 61, the inner diameter of the shortcylindrical portion 83 b is set larger than the outer diameter of themovement restricting portion 74 f, and the side wall of the extendedcylindrical portion 74 b of theinsertion member 74 is provided with anotch portion 84 formed by cutting a part of the side wall of the extendedcylindrical portion 74 b to allow the holdingmember 83 to move. - When the
brake cable 37 is pulled as illustrated inFIG. 5 to drive theparking brake lever 34 from the non-operation position toward the operation position, the disc springs 80 are prevented from being removed from therecess 81 because the outer peripheral portion of theretainer 82 makes contact with the shortcylindrical portion 83 b of the holdingmember 83. In addition, when thescrew shaft 38 moves so as to loosen thebrake cable 37, thecap 76 abuts against themovement restricting portion 74 f as illustrated inFIG. 10(a) , and then theelectric motor 40 continues the operation, thenut 61 that rotates relative to thescrew shaft 38 that stops movement in the axial direction moves in the axial direction so as to increase the interval from theball bearing 68 as illustrated inFIG. 10(b) , theretainer 82 abuts against themovement restricting portion 74 f of theinsertion member 74 in response to the movement in the axial direction of thenut 61, the disc springs 80 are compressed between thenut 61 and themovement restricting portion 74 f, thereby enabling an increase in the load on theelectric motor 40. - A mount
cylindrical portion 85 extending backward and inward in the vehicle width direction is provided integrally in a projecting manner on theback plate 13 of thedrum brake device 11. This mountcylindrical portion 85 is provided with a large-diametercylindrical portion 85 a with one end that is open backward and inward in the vehicle width direction and a small-diametercylindrical portion 85 c that is concentrically continuous to the large-diametercylindrical portion 85 a with astep portion 85 b provided between the small-diametercylindrical portion 85 c and the other end of the large-diametercylindrical portion 85 a. In addition, theactuator case 39 is mounted to the mount cylindrical portion by inserting the second accommodatingcylindrical portion 46 of thefirst cover member 48 in theactuator case 39 of theelectric actuator 36 into the large-diametercylindrical portion 85 a and engaging a C-shapedlocking ring 88 mounted to the outer periphery of the second accommodatingcylindrical portion 46 with a lockinggroove 87 formed in the inner periphery of the large-diametercylindrical portion 85 a. - When the
actuator case 39 is mounted to the mountcylindrical portion 85 of theback plate 13 as described above, theactuator case 39 is mounted to the rear side in the front-rear direction of the vehicle of theback plate 13 and theconnector portion 48 b is oriented to the rear side in the front-rear direction of the vehicle. In addition, abellows boot 89 for covering a projection portion of thescrew shaft 38 from the second accommodatingcylindrical portion 46 is provided between the outer periphery of the supportcylindrical portion 46 b of the second accommodatingcylindrical portion 46 and the outer periphery of one end portion of thescrew shaft 38. - The
brake cable 37 is a bunch of a plurality oftwisted wires 92 and generates a twisting force in the direction indicated byarrow 91 inFIGS. 11(a) and 11(b) when pulled in the direction indicated byarrow 90 inFIG. 11(a) to obtain the parking brake state. A setting is made so that the direction in which the twisting force in this case acts on thescrew shaft 38 is the same as the rotational direction of thenut 61 when theelectric motor 40 operates in the direction loosening thebrake cable 37 for switching from the parking brake state to the parking brake release state. - Next, the operation of the embodiment will be described. The
nut 61 of themotion conversion mechanism 41 capable of converting a rotational motion generated by theelectric motor 40 to a linear motion of thescrew shaft 38 connected to thebrake cable 37 is screwed onto thescrew shaft 38 movably in the axial direction within a restricted range in a direction along the axial line of thescrew shaft 38, themovement restricting portion 74 f that restricts the movement end in the axial direction of thescrew shaft 38 in movement to the side loosening thebrake cable 37 to reach the parking brake release state is provided in a fixed position in theactuator case 39, and the disc springs 80, which are resilient members, are interposed between thenut 61 and theinsertion member 74 accommodated and fixed in theactuator case 39 so as to be compressed in response to movement of thenut 61 in the axial direction after thecap 76 fixed to thescrew shaft 38 abuts against themovement restricting portion 74 f when thescrew shaft 38 moves in the axial direction to the side loosening thebrake cable 37, so the load on theelectric motor 40 can be increased by compression of the disc springs 80. Accordingly, theelectric motor 40 can be controlled appropriately and the members constituting themotion conversion mechanism 41 can be prevented from shifting to a lock state. Furthermore, since thenut 61 is relatively movable in the axial direction with respect to thescrew shaft 38, generation of an operating sound in parking brake release operation can be prevented. In addition, since the disc springs 80 are provided between theinsertion member 74 accommodated and fixed in theactuator case 39 and thenut 61, the strength of theactuator case 39 does not need to be increased more than necessity. - In addition, since the
movement restricting portion 74 f is provided integrally with theinsertion member 74 so that the disc springs 80 are present between themovement restricting portion 74 f and thenut 61, the internal structure of theactuator case 39 can be simplified while suppressing an increase in the number of components by providing the disc springs 80 between thenut 61 and themovement restricting portion 74 f provided integrally with theinsertion member 74. - Furthermore, since the resilient members are the disc springs 80, the space that needs to be reserved in the
actuator case 39 to dispose the disc springs 80 can be reduced and theactuator case 39 can be small-sized. - In addition, since the
brake cable 37 is formed by twisting the plurality ofwires 92 so as to generate a twisting force when pulled and the direction in which the twisting force acts on thescrew shaft 38 is the same as the rotational direction of thenut 61 when thebrake cable 37 is loosened, even if thenut 61 is rotated so as to obtain the parking brake state, thescrew shaft 38 is rotated and reaches a rotary position A indicated by the dotted line inFIG. 9 due to the rotation of thenut 61, and the rotation restrictingprojection portions 76 b abut against the side surface of therotation restricting grooves 75, the twisting force generated in thebrake cable 37 acts on thescrew shaft 38 in the direction in which the rotation restrictingprojection portions 76 b moves away from the side surface of therotation restricting grooves 75. Accordingly, when thescrew shaft 38 is moved in the axial direction to shift to the parking brake state by pulling thebrake cable 37, it is possible to prevent the components (that is, the guidecylindrical portion 74 a of theinsertion member 74 and the rotation restrictingprojection portions 76 b of the cap 76) constituting the rotation restricting means 73 from making strong contact with each other, reduce the driving torque of theelectric motor 40 by reducing the sliding resistance, and reduce wear of the guidecylindrical portion 74 a and thecap 76. - In addition, the rotation restricting
projection portions 76 b are returned to the vicinity of a rotary position B indicated by the dotted line inFIG. 9 by the twisting force from thebrake cable 37 when the parking brake state is maintained. Even when the rotation restrictingprojection portions 76 b of thecap 76 reach the rotary position B by the backward rotation of thenut 61 during switching from the parking brake state to the parking brake release state and make contact with the side surface of therotation restricting grooves 75 of theinsertion member 74, it is possible to prevent thecap 76 and theinsertion member 74 from strongly colliding with each other, suppress the generation of a slapping sound, and reduce the operating sound. - In addition, since the rotation restricting means 73 includes the plurality of rotation restricting
projection portions 76 b that are provided in the end portion of thescrew shaft 38 opposite to thebrake cable 37 and radially project from thescrew shaft 38 and the plurality of therotation restricting grooves 75 formed in theinsertion member 74 so as to be entered by the rotation restrictingprojection portions 76 b, the operating sound can be reduced more effectively by restricting the rotation of thescrew shaft 38 at a plurality of positions in the circumferential direction of thescrew shaft 38. - Although an embodiment of the invention has been described above, the invention is not limited to the above embodiment and various design changes can be made without departing from the spirit of the invention.
- For example, the insertion member does not need to be accommodated and fixed in the actuator case and the rotation restricting grooves may be formed in the actuator case.
Claims (2)
1. An electric parking brake device comprising:
a screw shaft that is connected to a brake cable;
an actuator case that supports the screw shaft movably in an axial direction thereof;
an electric motor that is supported by the actuator case rotatably forward and backward;
a motion conversion mechanism that has a nut to be screwed onto the screw shaft, enables conversion from a rotational motion generated in the electric motor to a linear motion of the screw shaft, and is accommodated in the actuator case; and
a rotation restricting device that restricts a rotational motion of the screw shaft,
wherein switching between pulling the brake cable and loosening the brake cable is performed by a change in a rotational direction of the electric motor,
wherein the brake cable is formed by twisting a plurality of wires, the direction of twisting is rotational direction of the nut when the brake cable is pulled.
2. The electric parking brake device according to claim 1 ,
wherein the rotation restricting device includes a plurality of rotation restricting projection portions that are provided in an end portion of the screw shaft opposite to the brake cable and radially project from the screw shaft, and
a plurality of rotation restricting grooves that is formed in the actuator case or an insertion member accommodated and fixed in the actuator case and entered by the rotation restricting projection portions.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US18/370,576 US20240010177A1 (en) | 2018-03-30 | 2023-09-20 | Electric parking brake device |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2018-068037 | 2018-03-30 | ||
JP2018068037 | 2018-03-30 | ||
PCT/JP2018/044929 WO2019187361A1 (en) | 2018-03-30 | 2018-12-06 | Electric parking brake device |
US202017043296A | 2020-09-29 | 2020-09-29 | |
US18/370,576 US20240010177A1 (en) | 2018-03-30 | 2023-09-20 | Electric parking brake device |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2018/044929 Division WO2019187361A1 (en) | 2018-03-30 | 2018-12-06 | Electric parking brake device |
US17/043,296 Division US11794710B2 (en) | 2018-03-30 | 2018-12-06 | Electric parking brake device |
Publications (1)
Publication Number | Publication Date |
---|---|
US20240010177A1 true US20240010177A1 (en) | 2024-01-11 |
Family
ID=68060559
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/043,296 Active 2040-07-27 US11794710B2 (en) | 2018-03-30 | 2018-12-06 | Electric parking brake device |
US18/370,576 Pending US20240010177A1 (en) | 2018-03-30 | 2023-09-20 | Electric parking brake device |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US17/043,296 Active 2040-07-27 US11794710B2 (en) | 2018-03-30 | 2018-12-06 | Electric parking brake device |
Country Status (5)
Country | Link |
---|---|
US (2) | US11794710B2 (en) |
EP (2) | EP3779230B1 (en) |
JP (2) | JP7240379B2 (en) |
CN (1) | CN111936761B (en) |
WO (1) | WO2019187361A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11794710B2 (en) * | 2018-03-30 | 2023-10-24 | Hitachi Astemo, Ltd. | Electric parking brake device |
CN111936760B (en) * | 2018-03-30 | 2022-04-19 | 日立安斯泰莫株式会社 | Electric parking brake device |
Family Cites Families (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
PL176894B1 (en) * | 1995-07-28 | 1999-08-31 | Edward Sosna | Inertial brake for trailers |
KR100279565B1 (en) * | 1998-12-29 | 2001-04-02 | 홍영철 | Steel cords for rubber reinforcement having different twist densities and twisting directions, and apparatus for manufacturing same |
JP4371286B2 (en) | 2000-04-12 | 2009-11-25 | 日清紡ホールディングス株式会社 | Operation cable connection device |
US6533082B2 (en) * | 2000-12-01 | 2003-03-18 | Dura Global Technologies, Inc. | Electric parking brake |
DE10361127C5 (en) * | 2003-12-22 | 2013-10-24 | Brose Fahrzeugteile GmbH & Co. Kommanditgesellschaft, Würzburg | Control device, in particular motor vehicle parking brake |
JP4176669B2 (en) * | 2004-03-26 | 2008-11-05 | 本田技研工業株式会社 | Parking brake device |
JP4928085B2 (en) * | 2004-06-30 | 2012-05-09 | 株式会社ハイレックスコーポレーション | Electric brake device |
EP2457785A1 (en) * | 2004-06-30 | 2012-05-30 | HI-LEX Corporation, Inc. | An electric cable drive device |
DE502004003693D1 (en) * | 2004-07-23 | 2007-06-14 | Siemens Ag | Control device, in particular motor vehicle parking brake |
US9211877B2 (en) * | 2006-01-16 | 2015-12-15 | Brose Fahrzeugteile Gmbh & Co. Kommanditgesellschaft, Wuerzburg | Actuator, particularly for a motor vehicle parking brake |
DE102006018625A1 (en) * | 2006-04-21 | 2007-10-25 | Siemens Ag | Control device, in particular motor vehicle parking brake |
JP2008075799A (en) * | 2006-09-22 | 2008-04-03 | Aisin Seiki Co Ltd | Linear motion actuator |
JP2012159164A (en) | 2011-02-02 | 2012-08-23 | Advics Co Ltd | Electric parking brake device |
JP2015110967A (en) * | 2013-12-06 | 2015-06-18 | 曙ブレーキ工業株式会社 | Actuator unit for drum-type electric parking brake |
US10138966B2 (en) * | 2014-03-11 | 2018-11-27 | Nissin Kogyo Co., Ltd. | Vehicle brake apparatus |
KR102297129B1 (en) | 2014-11-04 | 2021-09-02 | 현대모비스 주식회사 | Electronic parking brake apparatus |
JP6596294B2 (en) * | 2015-10-13 | 2019-10-23 | 日信工業株式会社 | Brake device for vehicle |
JP2017082834A (en) * | 2015-10-23 | 2017-05-18 | 株式会社アドヴィックス | Brake for vehicle |
CN111936760B (en) * | 2018-03-30 | 2022-04-19 | 日立安斯泰莫株式会社 | Electric parking brake device |
US11794710B2 (en) * | 2018-03-30 | 2023-10-24 | Hitachi Astemo, Ltd. | Electric parking brake device |
-
2018
- 2018-12-06 US US17/043,296 patent/US11794710B2/en active Active
- 2018-12-06 CN CN201880092036.3A patent/CN111936761B/en active Active
- 2018-12-06 EP EP18912782.2A patent/EP3779230B1/en active Active
- 2018-12-06 JP JP2020509628A patent/JP7240379B2/en active Active
- 2018-12-06 EP EP23207058.1A patent/EP4293247A3/en active Pending
- 2018-12-06 WO PCT/JP2018/044929 patent/WO2019187361A1/en active Application Filing
-
2023
- 2023-03-02 JP JP2023032078A patent/JP2023067950A/en active Pending
- 2023-09-20 US US18/370,576 patent/US20240010177A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
EP3779230A1 (en) | 2021-02-17 |
CN111936761A (en) | 2020-11-13 |
CN111936761B (en) | 2022-04-19 |
EP3779230B1 (en) | 2023-12-06 |
US11794710B2 (en) | 2023-10-24 |
EP4293247A3 (en) | 2024-03-13 |
JP7240379B2 (en) | 2023-03-15 |
JPWO2019187361A1 (en) | 2021-03-25 |
WO2019187361A1 (en) | 2019-10-03 |
EP3779230A4 (en) | 2021-12-22 |
EP4293247A2 (en) | 2023-12-20 |
JP2023067950A (en) | 2023-05-16 |
US20210016762A1 (en) | 2021-01-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20240010177A1 (en) | Electric parking brake device | |
CN109114132B (en) | Electric actuator and electric parking brake device | |
CN109114133B (en) | Drum brake device | |
US11787379B2 (en) | Electronic parking brake system | |
US11400908B2 (en) | Electric parking brake device | |
CN109649365B (en) | Electric parking brake device | |
CN111226055B (en) | Electric parking brake device | |
US20230061860A1 (en) | Electric parking brake and vehicle having the same | |
JP6896520B2 (en) | Vehicle drum brake device | |
JP7426473B2 (en) | Electric parking brake device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |