JPH0451382B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a braking device for a vehicle in which two front steering wheels are each equipped with a drum brake.

(Prior art) When installing a drum brake on each front wheel of a three- or four-wheeled vehicle having two steering front wheels, conventionally, a flange extending in the radial direction is formed integrally with the front wheel axle, and the drum brake is attached to this flange. The back plate that holds the brake shoes, etc., was bolted on. The bolts that secure this back plate here are installed parallel to the front wheel axis. For this reason, there was a problem in that the kingpin position was far away from the front wheel center plane that was perpendicular to the front wheel axis.

Particularly in small vehicles that use small-diameter front wheels, if the kingpin is far away from the center plane of the front wheel, the offset between the extension of the kingpin axis and the tire grounding point (kingpin offset) will increase, resulting in increased steering force and front wheel alignment. This has the disadvantage of increasing design limitations.

(Object of the Invention) The present invention was made in view of the above circumstances, and it is possible to increase the degree of freedom in designing front wheel alignment even when a small diameter front wheel is used by bringing the king pin and back plate closer together. In addition, it is an object of the present invention to provide a brake device for a vehicle that is easy to assemble and is suitable for reducing the number of parts.

(Structure of the Invention) According to the present invention, the object is to hold two front steering wheels rotatable to the left and right around the kingpin, and to install a drum brake near the widthwise center of each of these front steering wheels. In a vehicle, a back plate of the drum brake is fitted into a portion having a circular cross section formed on the root side of the front wheel axle from the tip side of the front wheel axle to position and fix the back plate, and a knuckle arm integral with the back plate and the front wheel axle is provided. This is achieved by a vehicle braking device characterized in that the braking reaction force is received by engaging concave and convex portions formed in the two portions. The present invention will be explained in detail below based on the illustrated embodiments.

(Example) Fig. 1 is a perspective view of a small four-wheel vehicle for traveling on rough terrain, which is an embodiment of the present invention, Fig. 2 is an elevational cross-sectional view of the vicinity of the front wheel axle, and Fig. 3 is a partially enlarged view thereof. FIG. 4 is a partially sectional plan view.

Two steering front wheels 10, 10 and two driving rear wheels 1
2 (only one shown) is equipped with wide ultra-low pressure tires. At both ends of the front axle 14 that connects both front wheels 10, 10, king pin brackets 16, which are approximately U-shaped when viewed from the front, are fixed so as to open toward the outside of the vehicle body. It is held by a king pin 18 so as to be movable. A front wheel axle 22 is integrally fixed substantially horizontally to this knuckle 20, and a known drum brake 24 is mounted on this front wheel axle 22. This drum brake 24 is located near the center of the steering front wheel 10 in the width direction.

This drum brake 24 is a brake shoe 26
The brake drum 30 includes a back plate 28 and a brake drum 30. On the root side of the front wheel axle 22, there is a third
As shown in the figure, there is a large diameter portion 32, a cylindrical medium diameter portion 36 adjacent to the large diameter portion 32 on the outside of the vehicle body via a flange surface 34, and a tapered portion 38 further outside the medium diameter portion 36. A cylindrical small diameter portion 40 located therebetween is formed. The back plate 28 is fitted into the medium diameter portion 36 and the small diameter portion 40,
One end surface thereof is in contact with the flange surface 34 to be positioned and fixed. The cylindrical boss portion 30a of the brake drum 30 is connected to the front wheel axle 2 by bearings 42 and 44.
It is supported by 2. A collar 46 is sandwiched between the inner races of these bearings 42, 44 to maintain a distance between them. The back plate 28 includes inner races and collars 46 of these bearings 42 and 44.
It is held pressed against the flange surface 34 by a nut 50 via a collar 48 on the shaft end side.

The camshaft 52 of the brake 24 is equipped with a nut 2.
A brake lever 54 that passes between the king pin 18 and the back plate 28 is fixed, and a brake wire 56 connected to its rotating end extends upward from near the upper end of the king pin 18. Therefore, the deflection of the wire 56 during steering is small.

At opposing edges of the back plate 28 and the brake drum 30, a waterproof labyrinth 58 is formed which has a complicated step-like cross section and faces each other with a slight distance between them. The brake drum 30 has a flange 60
is integrally molded, and a split wheel 62 is fixed thereto with bolts 64. This wheel 62
The above-mentioned wide ultra-low pressure tires are installed on the vehicle.

As shown in FIG. 4, the back plate 28 is integrally formed with a radially long recess 64, while a knuckle arm 66 is integrally fixed to the knuckle 20, and a recess 68 provided on the outer edge of the knuckle arm 66 is integrally formed with the back plate 28, as shown in FIG. is engaged with the recess 64.
A brake reaction force applied to the back plate 28 during braking is transmitted to the knuckle arm 66 and the knuckle 20 via these concave and convex portions 64 and 68.

In FIG. 1, 70 is a bar handle, 72 is a steering shaft, and the rotation of this steering shaft 72 is transmitted to the knuckle arm 66 via a pitman arm and a tie rod (both not shown) fixed to the lower end of the steering shaft. The front wheels 10 are steered.

In addition, as shown in FIG. 4, the knuckle arm 66
The inner edge 66a of the kingpin bracket 16 is connected to the inner surface 16 of the kingpin bracket 16 when the front wheel 10 is steered to the inside in the turning direction.
a, and functions as a steering stopper.

In Figure 1, 74 and 76 are the front and rear fenders, and 78
80 is an engine, 80 is a fuel tank, 82 is a driver's seat, and on the right side of the bar handle 70 is a brake lever 84 connected to the brake wire 56.
is installed.

Therefore, when this brake lever 84 is squeezed, the brake shoe 26 is pressed against the inner surface of the brake drum 30 by the camshaft 52, and a braking force is generated. As described above, the brake reaction force applied to the back plate 28 at this time is transmitted to the knuckle 20 via the concave and convex portions 64 and 68.

In this way, the back plate 28 has concave and convex portions 6.
4 and 68 engage the knuckle arm 66, there is no need to use bolts and nuts to fix the back plate to the front wheel shaft side flange as in conventional devices, and the distance between the knuckle 20 and the back plate 28 can be reduced. In other words, the king pin 18 can be brought closer to the center plane of the front wheel 10. Therefore, even with a small diameter front wheel, the king pin offset does not become excessive, increasing the degree of freedom in designing the front wheel alignment.

Furthermore, since the back plate 28 is held directly at the root side of the front wheel axle 22, only the bearings 42, 44 and the front wheel axle 22 are interposed between the brake drum 30 and the back plate 28. Therefore, if the thicknesses of the flange surface 34 and the boss portion of the back plate 28 are controlled with high precision, the distance between the opposing outer peripheral edges of the brake drum 30 and the back plate 28 can also be maintained with high precision. Therefore, the waterproof labyrinth 58
The dimensions can also be set smaller, making it possible to improve waterproof and dustproof properties. In addition, since a medium diameter portion 36 and a large diameter portion 32 are installed on the root side of the front wheel axle 22, the front wheel axle 22
while increasing the strength against bending stress of the front wheel axle 22.
The tip side of the brake drum 30 can be made thinner, which is suitable for reducing the diameter of the boss portion 30a of the brake drum 30 and further reducing the size of the brake 24 itself. Furthermore, since the back plate 28 is fitted to the circumferential surfaces of the medium and small diameter portions 36 and 40, there is no need for special disassembly tools required when the back plate 28 is tapered fitted to the front wheel axle 22. , the ease of disassembly and maintenance also improves.

(Effects of the Invention) As described above, the present invention provides a cross section in which a back plate is formed near the root of the front wheel axle when a drum brake is installed near the widthwise center of a steering front wheel that rotates left and right around a king pin. Fits into the circular part from the tip side of this front wheel axle to position and fix it, while
The brake reaction force is received by engaging the concave and convex parts formed on the knuckle arm and the back plate, which are integral with the front wheel axle, so that
The kingpin can be brought closer to the brake compared to the conventional device in which a flange is provided at the base of the front wheel axle and the back plate is bolted to this flange. Therefore, even when using small-diameter tires, the king pin offset does not become excessive, increasing the degree of freedom in designing the front wheel alignment. Furthermore, the number of parts is reduced and ease of assembly is improved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a four-wheeled vehicle according to the present invention, FIG. 2 is a sectional view of the vicinity of the front wheel axle, FIG. 3 is a partially enlarged view thereof, and FIG. 4 is a partially sectional plan view. 10...Front wheel, 22...Front wheel axle, 24...Drum brake, 28...Back plate, 32...
Large diameter part on the root side, 40... Small diameter part on the root side, 64
...Concave portion, 66...Natsukuru arm, 68...Convex portion.

Claims (1)

[Scope of Claims] 1. In a vehicle in which two front steering wheels are each held rotatably to the left and right around a king pin, and each of the front steering wheels is equipped with a drum brake near the widthwise center thereof, The back plate is fitted from the tip side of the front wheel axle into a circular section formed at the root side of the front wheel axle to position and fix the back plate, and a recess formed in the back plate and a knuckle arm integral with the front wheel axle. - A vehicle brake device characterized in that a convex portion is engaged to receive a brake reaction force.