JP6298777B2 - Disc brake device - Google Patents

Description

  The present invention relates to a technique for preventing brake noise in a ball cam type disc brake device.

  Conventionally, a technique in which a ball cam type disc brake device is mounted as a braking device for a traveling vehicle has been publicly known (see, for example, Patent Document 1). A ball cam type disc brake device includes a friction plate engaged with a brake shaft, a brake plate engaged with a brake housing, a cam plate that presses the friction plate against the brake plate, and a cam. A ball arranged between the plate and the housing, and a brake arm for rotating the cam plate, the cam plate is formed in a ring shape, and an engagement groove for engaging the ball is formed on one side of the same circumference. A plurality of the engaging grooves are arranged at predetermined angles on the upper side, and the engaging grooves are inclined in the rotational direction and formed in the shape of raindrops (tears). In such a configuration, when the brake arm is rotated by operating means such as a brake pedal, the cam plate is rotated, the ball rides on the slope, and the gap between the cam plate and the housing is widened to press the friction plate and the brake plate. It was set as the structure which made it brake.

JP 7-332404 A

  In the case of the ball cam type disc brake device as described above, the brake arm acts on the cam plate at a position off the center of the cam plate and rotates. Becomes uneven in the circumferential direction. As a result, a brake squeal occurred and uneven wear occurred on the friction plate, brake plate, and cam plate. Therefore, the bias of the pressing force due to the cam plate is corrected so that the friction plate and the brake plate are pressed uniformly to prevent brake squeal and to prevent uneven wear and prolong the life of the parts.

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
That is, in claim 1, a friction plate and a brake plate disposed on the brake shaft, a ring-shaped cam plate provided with an engagement groove for engaging a plurality of balls on one side surface, and the cam plate are rotated. A plurality of balls arranged on the same circumference around the brake shaft, and an interval between the plurality of balls arranged on the brake actuator side. It is so wide that it is arranged, and it is arranged so as to be narrow on the opposite side.

In claim 2, the engagement insertion groove that engages the front Symbol ball deep enough to be placed on the brake actuating side are those shallow enough to be positioned on the opposite side.

As effects of the present invention, the following effects can be obtained.
In other words, when the brake arm is rotated and braked, the friction plate and the brake plate are evenly pressed to prevent the occurrence of brake squealing and the friction plate and the brake plate can be prevented from wearing unevenly. The life of the friction plate and brake plate can be extended.

The whole side view of a tractor provided with the ball cam type disc brake device concerning the embodiment of the present invention. A front sectional view of a rear axle case that houses a ball cam type disc brake device. Similarly side view. The side view of a cam plate, and sectional drawing of an engaging groove. The figure of the Example which has arrange | positioned the ball unbalanced. The figure of embodiment which made the magnitude | size of a ball | bowl small as the brake actuator side. The figure of embodiment which made the thickness of the cam plate thin toward the brake operation body side. The figure of embodiment which leaves | separates the arrangement | positioning value of a ball | bowl from the center toward the brake actuating body side. The side view of the rear axle case of the Example which changes a natural frequency. The partial side view of the Example which opens a hole in protrusion and changes a natural frequency. The side view of the Example which arrange | positions several processus | protrusions and changes a natural frequency. The partial side view of the Example which provides a notch in a processus | protrusion, arrange | positions a ball | bowl and an elastic body, and changes a natural frequency. Front sectional drawing which shows other embodiment of the rear axle case which accommodated the ball cam type disc brake device.

  First, the overall configuration of the tractor 1 will be described with reference to FIG. 1 as an example of a work vehicle. In the following description, the F direction is defined as the front. An engine 3 is installed inside the bonnet 2, a steering handle 4 is provided at the rear of the bonnet 2, and a driver's seat 5 is disposed behind the steering handle 4.

  A transmission case 6 is connected to the rear portion of the engine 3 via a clutch housing, and rear axle cases 8 and 8 are connected to both sides of the transmission case 6. The rear axle cases 8 and 8 support rear wheels 10 and 10 via axles 13 and 13, and the vehicle body frame 11 supporting the engine 3 supports front wheels 9 and 9 via a front axle case. .

  The power from the engine 3 is transmitted to the rear wheels 10 and 10 via a transmission in the transmission case 6 so that the vehicle can run. Further, power is transmitted from the engine 3 to the PTO shaft via the PTO transmission in the transmission case 6 so that a working machine (not shown) can be driven.

  As shown in FIGS. 2 and 3, a ball cam type wet disc brake device 20, a speed reducer 30, and an axle 13 are accommodated in the rear axle case 8. The speed reduction device 30 is a planetary gear type, and the power after the shift is input to the differential device, and the differential output shaft 31 (hereinafter referred to as the brake shaft 31) protrudes left and right from the differential device via a differential mechanism. Is done. The brake device 20 is disposed on the differential output shaft 31 and on the outer periphery thereof. A sun gear 31a is formed at the tip of the brake shaft 31, and the sun gear 31a is inserted into the rear axle case 8, and the outer periphery of the sun gear 31a is engaged with the planetary gears 32, 32, and 32, respectively. The three planetary gears 32, 32, and 32 are meshed with the inner teeth of the ring gear 33 whose outer peripheral side is fixed to the inner surface of the rear axle case 8. The planetary gears 32, 32, and 32 are rotatably supported on a shaft provided on the carrier 34, the carrier 34 extends outward from the machine body, and the central portion of the extended portion of the carrier 34 is one end of the axle 13. Fixed to. The axle 13 is rotatably supported by the rear axle case 8, and the rear wheel 10 is fixed to the other end. Thus, the power transmitted to the differential device is decelerated by the planetary gear type reduction device 30 and transmitted to the axle 13. However, the speed reducer 30 is not limited to the planetary gear type, and may be constituted by a spur gear type speed reducer 30 comprising a small diameter gear (sun gear) 31a and a large diameter gear 35 as shown in FIG. is there. Further, the disc brake device 20 and the speed reduction device 30 may be arranged in the mission case 6 or the differential case.

  The brake device 20 includes a friction plate 21, a brake plate 22, a ball 23, a cam plate 24, and a brake operating body 25. In addition, although this embodiment demonstrates a multi-plate type brake, it is applicable also to a multi-plate type clutch. Disc-shaped friction plates 21 and 21 are disposed on the brake shaft 31, and ring-shaped brake plates 22 and 22 are disposed on the outer peripheral side of the friction plates 21 and 21 and are supported by the rear axle case 8. The friction plate 21 is fitted on the brake shaft 31 by a spline (or serration) so as to be slidable in the axial direction but not relatively rotatable. The brake plate 22 is arranged alternately with the friction plates 21 and 21 on the outer peripheral side of the friction plate 21, and is engaged with the rear axle case 8 serving as a housing so as to be slidable in the axial direction and not relatively rotatable. A cam plate 24 is arranged on one of the friction plate 21 and the brake plate 22 (on the right side in FIG. 2), and a plurality of balls 23, 23. The ring gear 33 is disposed opposite to the ring gear 33. An engagement groove 33a for engaging the ball 23 is formed on one surface of the ring gear 33 (left surface in FIG. 2). However, since the cam plate 24 is used to press-contact the friction plate 21 and the brake plate 22, the opposed member is not limited to the ring gear 33, but a housing such as the rear axle case 8 and the transmission case 6. Or a member fixed to the housing.

  As shown in FIG. 4, the cam plate 24 is formed in a ring shape and is disposed so as to be rotatable in the rear axle case 8. On one side of the cam plate 24, engagement grooves 24a, 24a, and the like for engaging the balls 23, 23,... At predetermined intervals (predetermined angles) are formed on the same circumference. The engaging groove 24a is formed in an approximately elliptical shape (a teardrop shape or a raindrop shape) in a side view, and is formed in an inclined groove so as to be shallow in the circumferential direction in a sectional view. Further, a protrusion 24b is formed at one end of the outer periphery of the cam plate 24 so as to protrude outward in the radial direction, and is disposed so as to be able to contact the brake operating body 25.

  As shown in FIGS. 2 and 4, the brake operating body 25 includes a brake arm 26 and an operating shaft 27. The operating shaft 27 is rotatable in parallel with the brake shaft 31 (axle 13) to the rear axle case 8. One end of the brake arm 26 is fixed to one end of the operating shaft 27. A semicircular (or two-sided) abutting portion 27a is formed in the middle portion of the operating shaft 27 in the axial direction, and the protrusion 24b of the cam plate 24 is disposed on the corresponding abutting portion 27a so as to be abuttable. . The other end of the brake arm 26 is connected to a brake pedal, a brake actuator, or the like via a wire or a rod (FIG. 1).

  In such a configuration, when the brake pedal is depressed, the brake arm 26 is rotated and the operating shaft 27 is also rotated. By this rotation, the contact portion 27a pushes the projection 24b to rotate the cam plate 24. When the cam plate 24 is rotated, the balls 23, 23... Move toward the shallower side of the engagement groove 24a, and the cam plate 24 moves in the axial direction to press the friction plate 21 and the brake plate 22 in pressure contact. . Thus, the brake shaft 31 is braked.

  A predetermined gap is provided between the cam plate 24 and the rear axle case 8 in order to facilitate assembly and make the cam plate 24 rotatable. In this configuration, when the balls 23, 23... And the engaging grooves 24a, 24a... Have the same shape and are arranged evenly on the concentric circumference, the brake device 20 is operated to brake the ball. In this case, the projection 24b arranged on one side of the cam plate 24 is pushed, and the surface pressure on one side of the cam plate 24 (in this embodiment, the projection 24b side and the brake operating body 25 side) is high, The opposite side tends to be lower, and the cam plate 24 cannot press the friction plate 21 and the brake plate 22 uniformly, and a frictional force is generated between the friction plate 21 and the brake plate 22. An unstable vibration occurred and a brake squeal occurred. Furthermore, uneven wear also occurred because the surface pressure was not constant.

  Therefore, in the first embodiment of the present invention, the balls 23, 23,... Are unequally arranged so that the surface pressure during braking is as uniform as possible. That is, as shown in FIG. 5, the distance between the balls 23 is arranged such that the brake actuating body 25 side is wide and the opposite side to the brake shaft 31 is narrow. In other words, the angle θ between the ball 23 and the center of the brake shaft 31 of the ball 23 is θ1, and the angle θ2, θ3, θ4 with the adjacent ball 23 is the angle with the brake actuator 25. It arrange | positions so that it may become so small as the opposite side ((theta) 1> (theta) 2> = (theta) 3> = (theta) 4). Furthermore, in other words, the number of balls 23 is such that the brake actuating body 25 side is small and the opposite side is many. In the present embodiment, the number of balls 23 is six, but the number is not limited and may be three or more. In addition, the balls 23, 23,... Are arranged vertically (or left / right) symmetrically, but can be asymmetrical. In this case, it corresponds to the rotation direction of the cam plate 24, the size of the gap, and the like. Thus, the friction plate 21 and the brake plate 22 are pressed evenly.

  In the second embodiment for making the surface pressure during braking substantially equal, as shown in FIG. 4, the depth of the engaging groove 24a for engaging the balls 23, 23. The engagement groove 24a is formed deeper as it is arranged on the 25th side, and shallower as it is arranged on the opposite side. That is, the depth E of the shallowest portion of the engaging groove 24a where the ball 23 is located when the friction plate 21 and the brake plate 22 are pressed against each other is the shallowest depth of the engaging groove 24a disposed on the brake operating body 25 side. The depth E2 of the shallowest part of the engaging groove 24a located on the opposite side is shallower (E1> E2) than the depth E1 of the part. In the case of FIG. 4, the engaging grooves 24a, 24a... Are arranged at an equal angle.

  Further, in the third embodiment for making the surface pressure at the time of braking substantially equal, as shown in FIG. 6, the size of the ball 23 is so small that it is arranged on the brake operating body 25 side, and on the opposite side. It is formed so large that it is arranged. That is, when the diameter of the ball 23 disposed on the brake actuating body 25 side is R1, the diameters R2 and R3 of the ball 23 disposed on the opposite side are larger (R1 <R2 <R3).

  Further, in the fourth embodiment for making the surface pressure at the time of braking substantially equal, as shown in FIG. 7, the thickness D of the cam plate 24 is thinner toward the brake actuating body 25 side, and is arranged on the opposite side. It is formed to be thicker. That is, the thickness D1 on the protrusion 24b side is configured to be smaller than the thickness D2 on the opposite side (D1 <D2). Note that this embodiment can also be applied to a cam-type multi-plate brake (clutch) that does not use balls.

  Further, in the fifth embodiment for making the surface pressure during braking substantially equal, as shown in FIG. 8, the arrangement position of the engaging groove 24a for engaging the balls 23, 23. The engaging groove 24a is arranged on the center side as it is arranged on the 25th side, and is arranged on the outer peripheral side as it is arranged on the opposite side. In other words, the distance (radius) L1 from the center of the engaging groove 24a on the brake operating body 25 side is configured to be shorter than the distance L2 (L1 <L2) from the center of the engaging groove 24a disposed on the opposite side. Configured to be

  However, in order to make the surface pressure during braking substantially equal, any two or more of the first to fifth embodiments may be combined. Further, in order to make the surface pressure during braking substantially equal, the hardness of the balls 23, 23... And the hardness of the cam plate 24 can be made softer toward the brake actuator 25 and harder toward the opposite side. It is.

  As described above, the friction plate 21 and the brake plate 22 disposed on the brake shaft 31, the ring-shaped cam plate 24 provided with the engagement groove 24a for engaging the plurality of balls 23 on one side surface, and the cam plate 24. In the ball cam type disc brake device 20 including the brake actuating body 25 that rotates the plurality of balls 23, 23,... Are arranged on the same circumference around the brake shaft 31, and the balls 23, 23,. Is disposed so as to be disposed closer to the brake actuating body 25 and is disposed closer to the opposite side, so that when the brake actuating body 25 is operated to bring the friction plate 21 and the brake plate 22 into pressure contact with each other. It is possible to reduce the unevenness and press the parts with a substantially uniform surface pressure to prevent the brake squealing and to prevent the friction plate 21 and the brake plate 22 from being unevenly worn. It was cut way. Further, the engaging groove for engaging the balls 23, 23... Can be easily formed by changing the processing position by cutting.

  Further, in the ball cam type disc brake device, the engaging grooves 24a, 24a,... For engaging the balls 23, 23,. Since it is formed so shallow that it is arranged on the side, when the friction plate 21 and the brake plate 22 are brought into pressure contact with each other, the bias can be reduced and contact can be made with substantially uniform surface pressure to prevent brake noise. Uneven wear of the friction plate 21 and the brake plate 22 can be prevented.

  Further, in the ball cam type disc brake device, the size of the ball 23 is smaller as it is disposed on the brake actuating body 25 side and larger as it is disposed on the opposite side, so that the friction plate 21 and the brake plate 22 Can be brought into pressure contact with substantially equal surface pressure, brake noise can be prevented, and uneven wear of the friction plate 21 and the brake plate 22 can be prevented. Further, in the ball cam type disc brake device, the cam plate 24 is formed so as to be thinner as it is disposed on the brake operating body 25 side and thicker as it is disposed on the opposite side, so that the friction plate 21 and the brake plate 22 are formed. Can be brought into pressure contact with a substantially uniform surface pressure to prevent brake noise and uneven wear of the friction plate 21 and the brake plate 22 can be prevented.

  Further, in order to prevent resonance (squeal) between the friction plate 21 and the brake plate 22, means for changing the natural frequency at the engaging portion between the brake plate 22 and the rear axle case (housing) 8 is provided. It is also possible to provide a configuration. That is, as a first embodiment of the means for changing the natural frequency, as shown in FIG. 9, a protrusion 22 a is formed on a part of the outer periphery of the brake plate 22 in order to lock the brake plate 22 to the rear axle case 8. A recess 8a for engaging the projection 22a is formed on the inner surface of the rear axle case 8. The elastic body 40 is interposed between the protrusion 22a and the recess 8a in a state where the protrusion 22a and the recess 8a are engaged. The elastic body 40 changes the natural frequency related to brake noise. Further, as a second embodiment of the means for changing the natural frequency, the elastic body 40 may be arranged at another position where the brake plate 22 and the rear axle case 8 come into contact. For example, the elastic body 40 is arranged at a position 180 degrees out of phase with the protrusion 22a. As the elastic body 40, for example, a spring, rubber or the like is employed.

  Further, as a third embodiment of the means for changing the natural frequency, as shown in FIG. 10, it is possible to adopt a configuration in which a hole 22b is opened in the protrusion 22a. By opening the hole 22b, a spring element is added to the protrusion 22a, and the natural frequency is changed.

  As a fourth embodiment of the means for changing the natural frequency, a plurality of spring elements may be arranged. For example, as shown in FIG. 11, several protrusions 22a having holes 22b are provided at appropriate intervals.

  As a fifth embodiment of the means for changing the natural frequency, as shown in FIG. 12, a notch 22c is provided in place of the protrusion 22a, and a ball 23 is fitted into the notch 22c, and the ball 23 and the recess 8a. The elastic body 40 may be interposed between the two. With the above configuration, when the friction plate 21 and the brake plate 22 are brought into pressure contact with each other, the natural frequency of the brake plate 22 is not changed to vibrate, and the brake squeal can be prevented.

20 Disc brake device 21 Friction plate 22 Brake plate 23 Ball 24 Mu plate 24a Engagement groove 25 Brake actuator 31 Brake shaft

Claims (2)

A ball cam comprising: a friction plate and a brake plate arranged on a brake shaft; a ring-shaped cam plate provided with an engagement groove for engaging a plurality of balls on one side; and a brake operating body for rotating the cam plate. Type disc brake device,
The plurality of balls are arranged on the same circumference around the brake shaft,
The disc brake device characterized in that an interval at which the plurality of balls are arranged is wider as it is arranged on the brake actuator side, and is narrower on the opposite side. Engaging insertion groove that engages the ball, the higher is disposed on the brake operating side deeply, disc brake device according to claim 1, characterized in that it is formed shallower is disposed on the opposite side.

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