JPS61291254A - Braking system structure for straddle type 4-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To enable a sufficient braking force to be provided by configurating a device in such a way that both a brake device and a related controlling device are provided for each of front wheels and rear wheels separately, and a two-leading type drum brake is applied to the front wheel as a front wheel brake device. CONSTITUTION:A saddle type four wheel drive vehicle 102 is so configurated that both two front wheels 105 and two rear wheels 106 are simultaneously driven by the power of an engine 103 which is mounted approximately at the center of a frame by the medium of a differential gear. In this case, two front wheels are provided with brake devices 3 and 4 consisting of two leading type drum brakes, and the rear left wheel 106 is provided with a brake device 38 consisting of a leading-trailing type drum brake. And the front wheel brake devices 3 and 4 are operated by applying fluid pressure which is produced by a master cylinder 1 with a brake lever 131 operated through a pressure control valve 2 which restricts an increase in pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a braking device structure for a straddle type four-wheel drive vehicle in which front and rear wheels are directly connected and driven.

<Prior Art> Four-wheeled vehicles equipped with low-pressure tires called balloon tires on four wheels are known, mainly for driving over rough terrain such as rough terrain, sandy terrain, and snowy terrain.

In order to further improve the running performance of such vehicles, for example, as disclosed in Japanese Utility Model Application Publication No. 60-61931,
It is advantageous to use all four wheels as driving wheels. Moreover, since a balloon tire is used that can be relatively easily deformed,
It is also possible to not provide a special differential device between the left and right wheels or between the front and rear wheels, which simplifies the structure and enables cost reduction and improved reliability of the vehicle.

<Problems to be Solved by the Invention> When designing a braking device for such a vehicle, problems specific to straddle type four-wheel drive vehicles arise.

First, since it is a straddle type, the rider tends to perform driving operations similar to those of a two-wheeled motor vehicle. In motorcycles, the front wheel is generally braked by a brake lever installed on the handlebar grip, the rear wheel is braked by a foot pedal, and the braking force between the front and rear wheels is balanced as necessary. I try to take it. Therefore, it is possible that a rider may try to brake only one of the front or rear wheels, but in a direct-coupled four-wheel drive vehicle, no matter which wheel the braking force is applied to, all brakes are applied via the drive shaft. It is also conceivable that the braking force is transmitted to the wheels, and for example, the braking force is generated on all wheels only by applying the brakes on the front wheels. Therefore, it is desirable that the brakes have sufficient capacity, but on the other hand, it is not necessarily desirable that an excessive braking force be generated when the vehicle is backed up due to the rider's straddling posture.

<Means for Solving the Problems> The present invention provides that a person who drives such a straddle type four-wheel vehicle,
It was created in consideration of the tendency to perform operations similar to braking a motorcycle when braking, and its main characteristics are:
This is a braking device structure for a straddle type four-wheeled vehicle in which the front and rear wheels are directly connected and driven, in which the braking device and its actuating device are provided separately for the front and rear wheels, and a two-leading type drum brake is used as the front wheel braking device. It is in.

In particular, it is preferable that the front wheel brake device be a hydraulically operated brake device, and that a pressure limiting valve be provided in the fluid pressure passage.

<Operation> Since a two-leading braking system is used for the front wheels, strong braking force can be obtained on the front wheels during normal driving even when using relatively small-diameter drum brakes, and when braking is applied when the vehicle is moving backwards. Therefore, excessive braking force is not generated.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 shows the entirety of a straddle-type four-wheel drive vehicle equipped with a braking device according to the present invention, with the body shell and seat removed.

The straddle type four-wheel drive vehicle 101 has an engine 103 mounted on a substantially medium-sized frame 102 made of a welded steel pipe structure.
The vehicle is equipped with a gearbox 11104 so that two front wheels 105 and two rear wheels 106 can be driven simultaneously. These front wheels 105 and rear wheels 106 use low-pressure tires called so-called balloon tires, and are driven by a direct coupling system without a center differential.

An air cleaner 107 is mounted above the engine 103, a muffler 109 connected to the exhaust manifold 108 of the engine and a gun tank 110 are arranged in parallel at the rear, and a battery 111 is arranged at the rear end. There is.

These upper parts are covered with a seat (not shown), and together with a pair of steps St protruding from the center of the lower part of the frame 102 in the left-right direction, the rider can ride in a saddle riding position.

The suspension system is a swing axle type for both the front and rear axles.
On the front axis side, a swing arm 112 is attached to the front of the frame 102.
A front axle 115, to which driving force is transmitted via a leading drive shaft 113 and a differential gear 114, which is pivotally supported to be able to swing freely, is attached to the front frame by a shock absorber 116 consisting of a coil spring and an oil damper. It is suspended from 102a. Braking devices 3.4 consisting of two-leading drum brakes, which will be described later, are mounted on both ends of the front axle.

The rear axle side has approximately the same configuration as the front axle side, but no differential device is provided, and the driving force is transmitted from a trailing drive shaft 117 to a rear axle 119 via a bevel gear box 118. .

The rear axle 119 side is also from the rear frame 102b,
Shock absorber 1 as well as front axle 115
It is suspended by 20. A braking device 38 consisting of a leading-trailing type drum brake is mounted on the right wheel side of the rear axle (see FIG. 1).

A relay arm 1 is installed approximately in the middle of the front axle 115.
21 are pivotally connected, and the right end of the relay arm and the knuckle arm 122 of the left front wheel 105 are connected to the tie rod 12.
3, and a knuckle arm 122 of the right front wheel 105 is connected to the left end by a tie rod 124.

Furthermore, the right end of the relay arm 121 and the tip of a pitman arm 126 fixed to the lower end of the steering shaft 125 are connected by a drag rod 127 using, for example, a ball joint. It is connected to a bar handle 129 that is rotatably provided on a steering column 128 that is tilted upward and fixed, and the front wheels can be steered by operating the bar handle.

The bar handle 129 is provided with grips 130 on the left and right sides, similar to a motorcycle, and brake levers 131 and 132 are provided on the front side of each grip. When the right brake lever 131 is gripped, fluid pressure is applied to the front wheel braking device 3 via the mask cylinder 1 (described later).
．． 4, and when the left brake lever 132 is grasped, the rear wheel braking device 38 is transmitted via the control cable 39.
is activated. The rear wheel braking device 38 is operated by fluid pressure from the mask cylinder 41 when the foot pedal 40 is pressed during driving, but it can also be used as a parking brake by using the left brake lever 132 of the bar handle 129. (See Figure 1).

1 and 2 schematically show a braking device according to the present invention, in which a right brake lever 131 is provided near a grip 130 of a bar handle 129 of a four-wheel drive vehicle.
It has a mask cylinder 1 operated by a pressure limiting valve (PCV) 2 for limiting the increase in fluid pressure, and a braking device 3.4 consisting of a two-leading drum brake provided on the left front wheel. On the other hand, as described above, a braking device 38 consisting of a leading trailing drum brake that applies braking force to the axle is installed on the right wheel side of the rear wheel, and a mask cylinder actuated by a foot pedal 40 while driving. Braking is performed by fluid pressure from 41, and when the vehicle is stopped, it is connected to the left brake lever 132 by a control cable 39 and used as a parking brake.

The mask cylinder 1 is of known type, in which the force applied to the brake lever 131 is applied via the piston rod 8 to the piston 9, which can exert pressure on the working fluid inside the cylinder chamber 11 and furthermore A fluid reservoir 10 is provided to prevent the working fluid inside 11 from being depleted.

The fluid pressure generated by the mask cylinder 1 is transmitted via the line 5 to the pressure limiting valve 2 .

The pressure limiting valve 2, as best shown in FIG. 2, has a casing 12 provided with an inlet 13 for introducing fluid and an outlet 14 for delivering fluid to the slave cylinder of the brake. . The outlet 14 is bifurcated so that the fluid can be sent equally to the left and right front wheels. Inside the casing 12, a small diameter bore 15 and a large diameter bore 16 are provided coaxially in the front and rear, respectively, and each outer end is closed by the casing 12 and a cover plate 17. Inside the small diameter bore 15 is a hollow spool valve body 18.
is received, and the skirt portion 18a of the spool valve body 18 extends into the large diameter bore 16.

Two annular seal members 19.20 are provided on the outer periphery of the spool valve body 18 at the front and rear, and an annular chamber 21 is formed between these two seal members 19.20.
It communicates with A cavity 22 is formed between the free end surface of the spool valve body 18 and the free end surface of the small diameter bore 15, and is always in communication with the outlet 14. A small diameter hole 23 is bored in the center of the free end of the spool valve body 18, into which the free end 24a of the auxiliary valve body 24 received in the hollow interior of the spool valve body 18 protrudes. Compared to the main body portion of the auxiliary valve body 24, its free end portion 24a is formed to have a smaller diameter, and the free end portion 24a is in contact with the main body portion.
1#a portion 24a is a valve seat formed at the inner opening of the hole 23 that receives the free end 24a of the auxiliary valve body 24 at the free end of the spool valve body 18. By working together with the spool valve body 18, communication between the inside and outside of the spool valve body 18 can be cut off.

Further, the main body portion of the auxiliary valve body 24 is biased away from a stopper member 25 by a compression coil spring 26, which is fluid-tightly and slidably received inside the skirt portion 8a of the spool valve body 18. and the stopper member 2
The other end of 5 is in contact with the cover plate 17. A compression coil spring 27 is sandwiched between the cover plate 17 and the spool valve body 18,
The spool valve body 18 is urged in the right direction in FIG. The outlet 14 of the fluid pressure restriction valve 2 is connected to the conduit 6.
7 to the left and right front wheel braking devices 3.4.

Next, the brake devices 3.4 for the front wheels will be explained, but since the configurations of the left and right brake devices are the same, one brake device 3.4 will be explained.
I will only explain about.

This braking device includes a brake drum 30 that is part of a wheel.
Two slave cylinders 31 are fixed to a base plate fixed to the vehicle body.

A piston rod 32 is connected from one end of the slave cylinder 31.
protrudes, and a locking member 33 is provided protruding from the other end of each slave cylinder 31. This locking member 33 can be moved in and out by rotating an adjustment screw 34.

Each end of the brake shoe 35 is locked in a groove formed at the tip of the locking member 33 and the piston rod 32, and a known brake lining 36 is attached to the outer peripheral surface of the brake shoe 35. There is. Further, a tension coil spring 37 is stretched between the base end side and the free end side of the two brake shoes 35.

This braking device is of a so-called two-leading type, in which each brake shoe 35 is pushed out in the same direction as arrow A), which is the rotational direction of the drum, as shown by arrow B. Since the servo action is strong, it generates a larger braking force for the fluid pressure applied to the slave cylinder 31 than a leading-trailing type braking device.

Next, the operation of the present invention will be explained.

Fluid pressure generated by the mask cylinder 1 is introduced from the inlet 13 of the pressure limiting valve 2, displacing the spool valve body 18 to the left in FIG. 1 to a position where it balances the restoring force of the compression coil spring 26.

When the input fluid pressure becomes higher than the above level, the spool valve body 1
8 is sufficiently displaced to the left, the auxiliary valve body 24 closes, and no further input fluid pressure is transmitted to the outlet 14. When the pressure on the outlet 14 side becomes relatively high, such as when the pressure in the mask cylinder 1 is released, the auxiliary valve body 24 is displaced to the left in FIG. 1, and the fluid pressure is transferred from the outlet 14 to the inlet. 1
It can be returned to 3.

Therefore, as the input pressure increases, the output pressure also increases.
If the input pressure increases beyond this point, the increase in output pressure will reach a plateau. The output pressure of the pressure limiting valve 2 is transmitted to the slave cylinder 3 of the brake device 3.4 of the left and right front wheels via a pipe 6.7.
1, and by pushing the brake shoes 35 apart and pressing the lining 36 against the brake drum 30, the required braking force can be generated. At this time, since the opening direction of both brake shoes 35 and the rotating direction of the brake drum 30 match, a strong self-servo action occurs and a strong braking force can be generated.

Figure 3 shows the relationship between input hydraulic pressure, braking force, and output hydraulic pressure. Curves P and Q indicate the braking force versus input hydraulic pressure for two-leading drum brakes and leading-trailing drum brakes, respectively. , curve S shows the output hydraulic pressure. The braking force of the two-leading drum brake is strongly applied to the given hydraulic pressure due to self-servo action, but due to the action of the pressure limiting valve 2,
When the input hydraulic pressure exceeds the level P, as shown by the solid line after Po, the increase in the output hydraulic pressure reaches a plateau, and accordingly, the increase in the braking force also reaches a plateau.

Therefore, when using such a two-leading drum brake, hydraulic pressure input can be easily controlled by using a pressure limiting valve.
After obtaining sufficient initial braking force, it is possible to easily control the braking force using the brake lever and improve the brake feeling. Further, as a characteristic of the two-leading type drum brake, the braking force when the vehicle is moving backward is smaller than the braking force Q of the leading-trailing type drum brake, as shown by the curve R in FIG. As a result, when a straddle-type four-wheeled vehicle backs up, even if the occupant operates the brake lever to apply strong front brakes, the braking force is evenly applied to all four wheels, stabilizing the vehicle. Since the vehicle can be stopped automatically, the vehicle is not braked suddenly.

<Effects of the Invention> As described above, according to the present invention, by using a two-leading drum brake, it is possible to obtain strong braking force even when using a drum brake with a relatively small diameter, and moreover, it is possible to obtain a strong braking force even when using a drum brake with a relatively small diameter. Even when only the front wheel braking device is activated, excessive braking force is not generated, which improves the usability of the vehicle.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of a chassis showing the configuration of a drive system and a brake system. FIG. 2 is an explanatory diagram schematically showing the configuration of a front wheel braking device according to the present invention. FIG. 3 is a graph showing changes in output hydraulic pressure and braking force with respect to input hydraulic pressure. FIG. 4 is an overall perspective view showing an example of a four-wheel drive vehicle to which the braking device shown in FIG. 1 is applied. 1...Mask cylinder 2...Pressure limiting valve 3.
4...Brake device @ 5-7...Pipe line 8...Piston rod 9...Piston 10...Fluid reservoir
11... Cylinder chamber 12... Casing 13.
...Inlet 14...Outlet 15.16...Bore 17...Lid plate 18...Spool valve body 1
8a...Skirt part 19.20...Seal member 2
1... Annular chamber 22... Vacancy 23... Hole
24... Auxiliary valve body 24a... Free end part
25... Stopper member 26. 27... Compression coil spring 30... Brake drum 31... Slave cylinder 32... Piston rod 33... Locking member 34...
・Adjustment screw 35...Brake shoe 36...
Lining 37...Tension coil spring 38...
Rear wheel braking device 39...Control cable 40...Foot pedal 41...Mask cylinder 1
01... Straddle type four-wheel drive vehicle 102... Frame 102a... Front frame 102b... Rear frame 103... Engine 104... Transmission 105.
...Front wheel 106...Rear wheel 107...Air cleaner 108...Exhaust manifold 109...Muffler 110...Gasoline tank 111...Battery 112...Swing arm 113...Leading type drive shaft 114... Differential device
115... Front axle 116... Shock absorber 117... Trailing drive shift V-shift 118.
... Bevel gear box 119 ... Rear axle 120 ... Shock absorber 121 ... Relay arm 122 ... Knuckle arm 123.124 ... Tie rod 125 ... Steering shaft 126 ... Pitman arm 127 ...・Drag rod 128...Steering column 129...Bar handle 130...Grip 131
...Right side brake lever 132...Left side brake lever Patent application Person: Honda Motor Co., Ltd. Representative Patent attorney: Yo Oshima - Figure 1 Figure 3

Claims (2)

[Claims] (1) A braking device structure for a straddle-type four-wheeled vehicle in which the front and rear wheels are directly connected and driven, in which the braking device and its actuating device are provided separately for the front and rear wheels, and a two-leading drum brake is used as the front wheel braking device. A braking device structure for a straddle type four-wheel drive vehicle characterized by the use of the brake system. (2) the front wheel braking device is a fluid pressure operated braking device;
A braking device structure for a straddle type four-wheel drive vehicle according to claim 1, characterized in that a pressure limiting valve is provided in the fluid pressure passage.