JPH05112215A - Brake pedal device of car - Google Patents

Abstract

PURPOSE:To reduce the frequency of generation of high pressure in a brake device by quickly increasing the pedal stamping force at the stage as going beyond the normal braking zone, and giving the operator a sense of stroke end. CONSTITUTION:A liquid pressure cylinder 8 is provided, which is operated approx. in the middle of the pedal stroke S when a brake pedal 1 is stamped, and is connected with an accumulator 15 through a high pressure hose 14. The accumulator 15 accommodates a compression coil spring 18 in the condition that it is given an initial shrinkage for providing a preload. When the accumulator 15 is operated via the cylinder 8 by stamping the pedal 1, at its early stage, the preload due to initial shrinkage of the spring 16 is added to the pedal stamping force, which thus increases rapidly to give the operator a sense of stroke end expressly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake pedal device suitable for vehicles, more specifically for industrial vehicles such as forklifts.

[0002]

Brake pedal devices for vehicles are generally
As shown in FIG. 6, the link system is established. FIG. 6 shows the case of an organ type brake pedal, and when the brake pedal 51 is depressed, the link arm 52,
The brake device 55 is operated via the push rod 53 and the master cylinder or the booster 54, and the relationship between the pedal stroke and the pedal effort (reaction force from the push rod 53 side) is generally Figure 7
As shown in, the characteristics are almost linear. However, in reality, there are some differences due to the play of the pedal, the change of the link ratio, and the like. As the booster, a hydraulic booster, an air pressure booster, a vacuum booster, or the like is used, although it depends on the vehicle type.

Further, depending on the vehicle, as shown in FIG. 8, a brake having a pedaling force characteristic such that a light pedaling force is obtained in the first period (normal braking region) of depression of the brake pedal and the pedaling force gradually increases in the latter period of pedaling (emergency braking region). Pedal devices have been put to practical use. An example of such a brake pedal device is JP-B-63-21455.

[0004]

In recent years, in order to reduce operator fatigue, the link ratio of a brake operating system is increased, especially the servo ratio of a booster, in order to obtain a desired braking ability with a light pedaling force. Improvements have been made. However, while such an improvement measure is effective in reducing operator fatigue, it has the side effect that the pedal stroke easily reaches full stroke with a light pedal force, which means that the pedal stroke is relatively small. This is especially noticeable in the case of organ type brake pedals.

As a result, the load on the brake device increases more than necessary, and durability is required more than before. Especially in the case of a forklift with a torque converter,
During the cargo handling work by operating the inching pedal, the operator deeply depresses the inching pedal in consideration of the unexpected movement of the vehicle due to the relation of the work mode (the brake pedal is interlocked with the depressing direction of the inching pedal).
There is a problem in that the hydraulic pressure of the brake device always rises to the maximum level, which adversely affects the life of the brake.

Even in the case of a brake pedal device having a pedaling force characteristic as shown in FIG. 8, it is actually difficult to clearly inform the operator of an inflection point (indicated by a broken line circle) at which the characteristic changes. Therefore, there is a high possibility that the pedal will be depressed more than necessary and the same problem as described above will occur.

By the way, the braking ability of the brake device is determined so as to comply with various standards and regulations in consideration of sudden braking in an emergency. However, it is known that the braking ability that is actually frequently used as the regular braking range is within half of the ability of the braking device.

In view of this, the present invention provides a stroke-end feeling to the operator by abruptly raising the pedal effort when the brake pedal is stepped up to the vicinity of the normal braking range. It is a technical problem to be solved to provide a brake pedal device that can reduce the frequency of high pressure generation in the brake device during normal use.

[0009]

In order to solve the above problems, the present invention is configured as follows. That is, in the brake pedal device, a hydraulic cylinder and a piston are housed in the cylinder so as to be movable in the axial direction, and the piston is unidirectionally moved by a spring housed in a predetermined preload state in the cylinder. A piston type accumulator having a biased structure and a high-pressure pipe for introducing the liquid in the hydraulic cylinder into the accumulator when the hydraulic cylinder is operated, and the normal braking area of the pedal stroke when the brake pedal is depressed. When the hydraulic cylinder operates in conjunction with the pedal link system in the vicinity of exceeding the above, the spring preload of the accumulator is added to the pedaling force.

[0010]

In the brake pedal device according to the present invention constructed as described above, when the brake pedal is depressed, the hydraulic cylinder operates near the normal braking range during the pedal stroke. Therefore, the liquid in the hydraulic cylinder acts on the piston of the accumulator through the high pressure pipe. At this time, since the spring for urging the piston is preloaded, the brake pedal is only increased abruptly until the pressure of the hydraulic cylinder reaches the pressure equivalent to the preload of the spring. Is substantially prevented from stepping on. As a result, a stroke end feeling is clearly given to the operator, and excessive depression of the brake pedal during normal use is avoided. In an emergency that requires sudden braking, the required braking capacity of the brake device can be obtained by overcoming the spring force of the accumulator and further depressing the brake pedal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A brake pedal device according to an embodiment of the present invention will be specifically described below with reference to the drawings. First, a first embodiment will be described based on FIGS. 1 and 2. The brake pedal device of this embodiment is applied to an organ type brake pedal, and when the brake pedal 1 is depressed, the brake device 5 is operated via the link arm 2, the push rod 3, the master cylinder or the booster device 4. The configuration for activating is the same as the conventional one. The brake pedal 1 is held at the brake release position by a return spring (not shown). Further, in FIG. 1, 6
Indicates a floor, and 7 indicates a rotation fulcrum of the brake pedal 1.

A hydraulic cylinder 8 is mounted on the upper surface of the floor 6 facing the lower surface of the brake pedal 1 so as to face upward. The hydraulic cylinder 8 comprises a cylinder body 9, a piston 10 slidably accommodated in the cylinder body 9, and a piston rod 11 projecting from above the cylinder body 9, and the tip of the piston rod 11 is The height position of the brake pedal 1 is set so as to come into contact with the lower surface of the pedal at an almost intermediate position during the pedal stroke S of the brake pedal 1.

The hydraulic cylinder 8 has a low pressure port 9a opened to the cylinder body 9 near the lower surface of the piston 10, and this low pressure port 9a is connected to a reserve tank 13 via a low pressure hose 12. .. The hydraulic cylinder 8 has a high pressure port 9b opened at the bottom of the cylinder body 9, and this high pressure port 9b is connected to the high pressure hose 1.
It is connected to the accumulator 15 via 4.

The accumulator 15 includes a cylindrical body 16 and a piston 17 housed in the cylindrical body 16 so as to be slidable in the axial direction.
And a compression coil spring 18 that is housed in the cylindrical body 16 and presses and urges the piston 17, and the compression coil spring 18 is preliminarily compressed so as to preload the piston 10. .. And
The liquid from the hydraulic cylinder 8 is introduced to the side where the compression coil spring 18 is further compressed. The accumulator 15 is installed at an appropriate portion of the machine base, preferably on the lower surface side of the floor 6.

The brake pedal device of the present embodiment is constructed as described above, and when the brake pedal 1 is depressed, the accumulator 15 causes the front stroke A (normal braking range) of the pedal stroke S to a substantially intermediate position. ) Is not operated, but is operated in the remaining second stage stroke B (emergency braking range). Therefore, in the front stroke A, the brake pedal 1 can be depressed with a light pedaling force (reaction force from the push rod 3 side) as in the conventional case. On the other hand, in the second stroke B in which the accumulator 15 operates, the lower surface of the pedal abuts against and pushes the piston rod 11 of the hydraulic cylinder 8, and the piston 10 passes through the low pressure port 9a and disconnects from the reserve tank 13. ,
The liquid in the hydraulic cylinder 8 is pressure-fed to the accumulator 15 via the high-pressure hose 14, and the accumulator 15
Is activated. Therefore, in the rear stroke B, in addition to the reaction force from the push rod 3 side, the accumulator 15
Since the reaction force due to is added, the pedaling force becomes high.

However, since the compression coil spring 18 of the accumulator 15 is pre-loaded with the initial compression as described above, the pedal depression force rapidly rises at the initial stage of the second stroke B. That is, the pedal effort suddenly increases until it reaches a magnitude equivalent to the preload due to the initial contraction of the compression coil spring 18, and during that time, the depression of the brake pedal 1 is substantially prevented, so that the operator feels a stroke end feeling. Can be given to.

Thus, according to the brake pedal device of the present embodiment, as shown in FIG. 2, the pedal depression force characteristic in which the pedal depression force suddenly changes stepwise between the normal braking range and the emergency braking range can be obtained. .. Therefore, the operator receives a stroke end feeling at an almost intermediate position of the pedal stroke S during normal use, thereby avoiding an excessive depression of the brake pedal 1 and further depressing harder in an emergency when sudden braking is sufficient. It is possible to secure a sufficient braking force.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the hydraulic cylinder 8 is mounted on the lower surface of the floor 6, and the piston rod 11 of the hydraulic cylinder 8 is the link arm 2 of the brake pedal 1.
Thus, the operation is started at an almost intermediate position of the pedal stroke S. Further, the reserve tank 13 is installed on the upper surface side of the floor 6 in consideration of easy confirmation of the remaining amount of the enclosed liquid and easy replenishment of the liquid. Other configurations are similar to those of the above-described first embodiment. Therefore, according to the second embodiment, in addition to the effect and advantage described in the first embodiment, the hydraulic cylinder 8 mounted on the lower surface of the floor 6 can be protected from rainwater, soil of shoe soles, mud and the like. There are advantages.

FIG. 4 shows a third embodiment of the present invention. This embodiment is an example applied to a suspension type brake pedal 1, and a hydraulic cylinder 8 is disposed above the link arm 2 so as to be actuated by the link arm 2 of the brake pedal 1, for example. It Also in the case of such a suspension type brake pedal, the same operational effect as in the case of the organ type brake pedal can be obtained.

Further, FIG. 5 shows a fourth embodiment of the present invention. This embodiment is an example in which a tension coil spring 19 is used in place of the compression coil spring 18 of the accumulator 15, so that the piston rod 11 of the hydraulic cylinder 8 penetrates the through hole 2a formed in the link arm 2 and It has a structure in which a flange 20 for locking is provided at the tip. The flange 20 of the piston rod 11 engages with the link arm 2 at a substantially intermediate position of the pedal stroke S when the brake pedal 1 is depressed, and adds the reaction force of the accumulator 15 to the pedal depression force. As in the case of, the pedal force is suddenly raised near the point where the normal braking range is exceeded,
It is possible to give the operator a stroke-end feeling.

Although the above-described brake pedal device is particularly effective for a forklift that frequently uses the brake device, its applicable range is not limited to the forklift and can be applied to other vehicles.

[0022]

As described in detail above, according to the present invention,
By giving the operator a stroke-end feeling in the vicinity of the normal braking range, it is possible to avoid excessive depression of the brake pedal during normal use. As a result, the frequency of occurrence of high pressure in the brake device is reduced, the load on the entire brake device is reduced, and the life of the brake device is extended. In addition, the reduction of the high-pressure generation frequency also reduces the frequency of operation of the booster (for example, the frequency of operation of accumulating compressed air, rotating the vacuum pump, etc.), which is effective in saving energy. Becomes

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a brake pedal device according to a first embodiment of the present invention.

FIG. 2 is a pedal stroke-pedal depression force diagram of the present invention.

FIG. 3 is an explanatory diagram of a brake pedal device according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a brake pedal device according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a brake pedal device according to a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a conventional brake pedal device.

FIG. 7 is a conventional standard pedal stroke-pedal depression force diagram.

FIG. 8 is a diagram showing a conventional improved pedal stroke-pedal force.

[Explanation of symbols]

1 ... Brake pedal 2 ... Link arm 8 ... Hydraulic cylinder 10 ... Piston 11 ... Piston rod 13 ... Reserve tank 14 ... High pressure hose 15 ... Accumulator 16 ... Cylindrical body 17 ... Piston 18 ... Compression coil spring

Claims (1)

[Claims] 1. A hydraulic cylinder and a piston are housed in a cylinder so as to be movable in the axial direction, and the piston is biased in one direction by a spring housed in the cylinder with a predetermined preload applied. And a high-pressure pipe for introducing the liquid in the hydraulic cylinder into the accumulator when the hydraulic cylinder operates, and exceeds the normal braking range of the pedal stroke when the brake pedal is depressed. A brake pedal device configured such that a spring preload of the accumulator is added to a pedal effort by the hydraulic cylinder operating in the vicinity in cooperation with a pedal link system.