JPS625098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake device for a hoisting winch of a crane or the like.

Normally, a brake device such as a crane hoisting winch is composed of a pedal A, a master cylinder B, a wheel cylinder C, and a brake band D, as shown in Fig. 1. When the pedal A is operated, the master cylinder B is is discharged to operate the wheel cylinder C and tighten the brake band D. The advantage of such a brake device is that when the brake is applied, the vibration of the brake band D turns into vibration of fluid pressure in the wheel cylinder C.
Since the pressure flow is directly transmitted to the pedal A via the master cylinder B, a good operating feeling can be obtained, and therefore accurate brake adjustment, that is, rotation control of the drum E is possible. On the other hand,
This device has disadvantages in that it requires a large operating force and requires adjustment of the initial clearance of the brake band D and clearance adjustment as the shoe wears, which is disadvantageous in terms of maintenance.

Since the proper operating range of pedal A is determined,
It is not possible to increase the link ratio between pedal A and master cylinder B in order to reduce the above-mentioned operating force, and reducing the size of master cylinder B will reduce the required fluid discharge amount, which is dangerous. . In other words, the master cylinder B has a capacity that can discharge enough fluid to fill the initial gap in the brake band D or the gap that increases as the brake shoe wears, that is, the play in the brake band, and to tighten the brake band D. It had to be large, and for that reason it had to become large. The relationship between this point, that is, the relationship between the rod stroke of master cylinder B and the fluid pressure of wheel cylinder C is shown in FIG.

The dotted curve A in the figure shows the initial state of the conventional device, and the curve B shows the state after the brake shoe has worn out. In curve A, the required rod stroke of master cylinder B is 0 to _S4 , and the fluid pressure in the wheel cylinder during that period is 0 to _P4 . Of the rod strokes 0 to _S4 , _S1 to _S4 are the effective brake control range, and 0 to _S1 are the strokes necessary to compensate for play in the brake band at the initial stage of operation. As the brake shoe wears, the play in the brake band D increases, so curve A gradually moves parallel to curve B, and the stroke play of master cylinder B increases from 0 to _S3 , making it difficult to control the brake. To do this, a stroke of 0 to _S5 is required. As described above, in the conventional device, it is necessary to compensate for the play in the brake band, which increases the capacity of the master cylinder and increases the operating force. In addition, with conventional devices, during assembly, it is necessary to adjust the brake band shoe clearance in order to obtain the performance of curve A, and the brake shoe wear progresses, causing the relationship between the wheel cylinder fluid pressure and the master cylinder stroke to change. If it moved to the right on the diagram from curve B in Figure 2, it would be necessary to adjust the brake band to close the shoe clearance.

In order to overcome these drawbacks, some systems have conventionally adopted a system that uses high oil pressure to control the fluid pressure in wheel cylinder C, but with this method, the original good operating feeling is lost. I didn't like it because of that.

In FIG. 2, the solid curve C shows the braking characteristics that the present invention seeks to obtain. That is, in the present invention, the rod stroke of master cylinder B is 0 regardless of the size of the brake band gap.
Wheel cylinder C within the range from to S ₀
It is intended that the fluid pressure within the brake can be increased to the brake effective pressure _P1 , and therefore the stroke _S0 to _S2 can always be in the effective brake control range. By doing this, the required stroke of master cylinder B can be reduced from S ₅ to S ₂ , and the link ratio between master cylinder B and pedal A can be correspondingly increased, so the operating force can be reduced to S ₂ of the conventional device. /S Can be increased by ₅ times (<1). In addition, in the brake control range, the wheel cylinder pressure is controlled in the same way as conventional devices, so a good operating feel is not lost. Furthermore, when the master cylinder stroke reaches S ₀ , the wheel cylinder pressure changes to P ₁ . Since the fluid is supplied from the outside, there is no need to adjust the shoe clearance, which is very advantageous in terms of maintenance.

The structural features of the present invention mainly reside in the master cylinder B. In other words, the rod of the master cylinder moves by itself from when the pedal begins to be depressed until it is depressed by a predetermined amount, and after that, the rod and piston are separated and a predetermined gap is created so that the rod pushes the piston. The tube side wall of the cylinder is provided with a pressure fluid inlet connected to a pressure fluid supply source outside the cylinder, and the piston of the cylinder has one end facing the pressure fluid inlet and the other end facing the pressure fluid inlet. A fluid passage that opens to the fluid outlet side in the cylinder tube and a valve mechanism that opens and closes the passage are provided, and the valve mechanism is opened during the pushing stroke of the rod alone at the initial stage of depression of the pedal, and the pressure is increased. By sending pressurized fluid from the fluid supply source into the wheel cylinder through the fluid passage, the fluid pressure within the wheel cylinder is increased to a predetermined value, and subsequent strokes are mastered by the rod pushing the piston. The structure is such that the fluid inside the cylinder is sent to the wheel cylinder.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows master cylinder B in an inoperative state.

1 is a cylinder tube, 2 is a piston, and 3 is a rod connected to pedal A. Piston 2 and rod 3 are separated so that only rod 3 can move a predetermined stroke independently at the initial stage of depression of pedal A, as will be described later. It's getting old.

Caps 11 and 12 are attached to both the rod side and the head side (hereinafter referred to as the right side and left side according to the diagram) of the cylinder tube 1, and the outlet port 13 provided on the left side cap 12 is connected to the wheel cylinder C. has been done. A compression coil spring 4 is interposed between the left side cap 12 and the piston 2, and this spring 4 always pushes the piston 2 to the right, so that the right end surface of the piston 2 is connected to the right side cap 1.
It is in contact with the inner surface of 1.

The piston 2 includes a passage 21 extending in the radial direction of the piston in an axially intermediate portion, and a passage 21 extending through the piston in the radial direction of the piston.
It has a right chamber 22 formed inside the right half of the piston perpendicular to the piston, and a left chamber 23 formed inside the left half in communication with the right chamber 22, and the right chamber 22 is connected to the cylinder tube 1. The inner rod side and left chamber 23 open to the head (fluid outlet) side, respectively. right ventricle 2
2 is constantly connected to the tank. Also, passage 21
is in continuous communication with a pressure fluid inlet 14 provided on the side wall of the cylinder tube 1, which inlet 14 is connected to a pressure fluid supply source (not shown).

5 is a plunger built into the piston 2, and 6 is a check valve thereof. The plunger 5 is slidably provided in the axial direction at the intersection of the passage 21 and the right chamber 22 of the piston 2, and is applied with spring force by coil springs 7 and 8 from both sides in the axial direction. The left spring 8 has a smaller spring force than the right spring 7 interposed between the plunger 5 and the rod 3, and when the plunger 5 is pushed by the rod 3 via the right spring 7, the left spring 8 is easily compressed and the plunger 5 moves to the left. FIG. 4 shows an enlarged view of the flow path structure of the plunger 5. As shown in the figure, the plunger 5 has a passage that communicates with the fluid passage 21 of the piston 2 and simultaneously closes communication with the right chamber 22 when the plunger 5 is pushed by the rod 3 and moved to the left by more than the play y as described above. 51 and the passage 5
A passage 52 extending to the left is formed continuously with the rod 3. When the rod 3 is not operated, the passage 52 is formed continuously with the rod 3.
2 opens into the right ventricle 22, that is, the tank.

The check valve 6 has a headed pin shape and is fitted into the left end of the left chamber 23 of the piston 2 so as to be slidable in the axial direction. A flow path 61 communicating with the piston left chamber 23 is formed in the axial center of the check valve 6, and this flow path 61 opens into the head side of the cylinder tube 1 through a hole 62. The check valve 6 has its right end stopped by a pin 15 which passes through the left chamber 23 of the piston 2 in the radial direction and is fixed to the cylinder tube 1, and its left end is supported by a spring 9.

The rod 3 is introduced into the cylinder tube 1 through the right side cap 11, and its left end is connected to the piston 2.
It is inserted into the right ventricle 22 of. A flange portion 31 is formed near the left end of the rod 3, and the rod 3 is pushed to the right by the spring force of the return spring 100 of the pedal A, and the flange portion 31 is in contact with the inner surface of the right side cap 11. In this state, a gap x is formed between the flange 31 and the right end surface of the piston 2, and the rod 3 can slide independently of the piston 2 within this gap x. Note that the rod 3 is provided with a notch 200 for communicating the right chamber 22 with the tank even when the flange 31 comes into contact with the right end surface of the piston 2.

Next, the operation of this brake device will be explained.

From the state shown in FIG. 3, when the pedal A is started to be depressed and the rod 3 is pushed in, the plunger 5 is pushed to the left via the coil spring 7 as described above. If the plunger 5 moves beyond the play y, the pressure fluid from the pressure fluid supply source will flow from the pressure fluid inlet 14 to the passage 21 of the piston 2 - the passage 51 of the plunger 5 -
It flows into the head side of the cylinder tube 1 through the path 52, the left chamber 23 of the piston 2, the flow path 61 of the check valve 6, and the hole 62, and is fed into the wheel cylinder C from the outlet port 13. At this time, the passage 21 of the piston 2 and the piston right chamber 22 are blocked by the plunger 5.

In this way, the cylinder pressure of the wheel cylinder C increases, and at the same time, the pressure on the outflow side of the plunger 5 increases, and if the force determined by multiplying the cross-sectional area of the plunger 5 by the pressure overcomes the spring force of the coil spring 7, then Plunger 5 is pushed back to the right. As a result, the passage 21 is blocked and the supply of pressure fluid to the wheel cylinder C is stopped. The wheel cylinder pressure P at this time is the coil spring 7
When the spring constant k is the pushing amount S of the rod 3, and the cross-sectional area N of the plunger 5, it is given by P=k(S-y)/N. If you push rod 3 further, P
Based on the above formula, increases in proportion to the rod pushing amount. Therefore, regardless of the size of the shoe clearance of the brake band D, fluid is fed into the wheel cylinder C up to a pressure determined by the amount of rod depression.

As mentioned above, the spring force of the coil spring 7 is selected so that the wheel cylinder pressure P becomes the brake effective starting point pressure P ₁ in Fig. 2 when the rod 3 moves x strokes independently and hits the piston 2. If this is done, regardless of the amount of play in the brake band D, if the rod 3 makes x strokes, the wheel cylinder pressure will definitely fall within the brake control range P ₁ to _{P 4} in FIG. 2.

In addition, rod 3 makes x stroke and piston 2
At the time when the check valve 6 is hit, the hole 62 is slightly opened, so the pressure in the wheel cylinder C is maintained at P ₁ while the check valve 6 strokes by the opening distance t, and the piston 2 is moved beyond the distance t. The pressure starts to rise from the moment the check valve 6 closes after the stroke. Therefore, the increase curve of the wheel cylinder pressure P with respect to the rod stroke is, in detail, the fifth curve.
The result will be as shown in the figure. However, since the strokes y and t are minute, they are omitted in FIG. 2.

From the time when the check valve 6 is closed, the rod 3 directly operates the piston 2 in the same way as in the conventional piston-rod direct connection type master cylinder, thereby controlling the pressure rise from point Q on the curve C in FIG. During this time, the left chamber 23 of the piston 2 always maintains the pressure of _P1 .

Then, when the rod 3 is returned, the wheel cylinder pressure decreases along the curve C in FIG. 2, contrary to the pressure increase, and the master cylinder B returns to the state shown in FIG. 3.

In the above embodiment, the piston has a built-in valve mechanism that increases and decreases the pressure according to the rod stroke, but the configuration of the valve mechanism and the piston can be changed as appropriate for implementation. Furthermore, the present invention is not limited to winches for cranes, etc.
It can be widely applied to brake systems that use master cylinders and wheel cylinders in automobiles and other various machines.

As described above, according to the present invention, there is no difference in the brake control range from conventional brake devices, and therefore it is possible to reduce the operating force while maintaining a good operating feeling, and also to adjust the brake band clearance. This makes it unnecessary, and is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of the brake device, Fig. 2 is a diagram showing the rise curve of wheel cylinder pressure with respect to the rod stroke of the master cylinder, Fig. 3 is a sectional view of the master cylinder according to the present invention, and Fig. 4 5 is an enlarged sectional view of the same part, and FIG. 5 is a diagram showing the pressure increase curve in FIG. 2C in more detail. A...Pedal, B...Master cylinder, C...
...Wheel cylinder, D...Brake band, 1
...Master cylinder cylinder tube, 2...
...Same piston, 3...Same rod, 14...Pressure fluid inlet, 21, 23, 51, 52, 61, 62...
...Passage for pressure fluid, 5... Plunger, 6... Check valve, x... Stroke by rod alone.

Claims (1)

[Claims] 1. In a brake device such as a winch that operates a brake band via a master cylinder and a wheel cylinder by pedal operation, the rod of the master cylinder moves by itself from the start of pedal depression until the time when the pedal is depressed by a predetermined amount. After that, the rod and piston are separated and placed facing each other with a predetermined gap so that the rod pushes the piston, and the tube side wall of the cylinder is
A pressure fluid inlet connected to a pressure fluid supply source outside the cylinder is provided, and the piston of the cylinder has a fluid passage whose one end faces the pressure fluid inlet and the other end opens to the fluid outlet side in the cylinder tube; A valve mechanism for opening and closing the passage is provided, and the valve mechanism is opened during the pushing stroke of the rod alone at the initial stage of depression of the pedal, and the pressure fluid from the pressure fluid supply source is passed through the fluid passage. By feeding the fluid into the wheel cylinder, the fluid pressure in the wheel cylinder is increased to a predetermined value, and the subsequent stroke is such that the rod pushes the piston to feed the fluid in the master cylinder into the wheel cylinder. A brake device for a winch, etc., characterized by: