JPH09175368A - Brake device of winch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep small the operation amount and operating force of a brake pedal while the stroke of a brake cylinder is enlarged, and give a good operating feeling by suppressing the hysteresis of the brake characteristics. SOLUTION: A brake device concerned for a winch is equipped with a master cylinder 10 to emit a brake operation pressure Pout in compliance with the stamping of a brake pedal 11, a positive cylinder 7 to work in the direction of braking a winch drum 3 in response to the brake operation pressure Pout, and a negative cylinder 8 which works in the direction of braking the drum 3 when the brake disengaging pressure Pr given from a hydraulic pump 14 lowers and works in the direction of disengaging the brake application on the drum 3 when the brake disengaging pressure Pr rises. An interlocking mechanism 19 is furnished to sink Pr applied to the negative cylinder 8 interlocking with the braking operation of the brake operation member 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winch brake device for braking the rotation of a winch by using hydraulic pressure or the like.

[0002]

2. Description of the Related Art As a winch braking device mounted on a construction machine such as a crane, a master cylinder which operates in response to a depression operation of a brake pedal, and a direction in which a winch winding drum is braked by an output pressure of the master cylinder. When a predetermined brake release pressure is introduced from a pressure source such as a hydraulic pump, a first brake cylinder that operates to the above and a biasing means such as a spring constantly biases the hoisting drum in a braking direction. There is a second brake cylinder that operates in the direction of releasing the braking of the winding drum against the above (see, for example, JP-A-1-145997). In addition, a general winch drive circuit,
A clutch for connecting and disconnecting the winch driving hydraulic motor and the winch winding drum is provided. The brake by the first brake cylinder described above may be called a positive brake, and the brake by the second brake cylinder may be called a negative brake.

In a winch equipped with the above two types of brake mechanisms and clutches, when the clutch is turned on to connect the hydraulic motor to the winding drum and the braking of the winding drum by each brake cylinder is released, the winding drum is hydraulically operated. It is driven according to the rotation of the motor. On the other hand, when releasing the brake release pressure from the second brake cylinder,
The winding drum is prevented from rotating regardless of whether the clutch is turned on or off or the brake pedal is depressed. Then, when the brake pedal is loosened while the clutch is off and the braking by the second brake cylinder is released, the hoisting drum rotates in the hoisting direction due to the weight of the suspended load or hook, which is a so-called free-fall state. .

[0004]

In the above-mentioned brake device, the brake cylinder provided around the outer periphery of the winding drum is tightened by the brake cylinder,
Alternatively, a brake shoe fixed to a piston rod of a brake cylinder is pressed against the winding drum to brake the winding drum by frictional force. For this reason, unless the operating stroke of the brake cylinder is set sufficiently large, the friction member such as the brake band comes into contact with the hoisting drum during free fall, causing abnormal noise or abnormal heat generation.
Problems such as a lightweight suspended load not falling will occur. However, with respect to the brake cylinder (first brake cylinder) of the positive brake, when the stroke is increased, the amount of depression of the brake pedal increases, and the operability deteriorates.

In order to reduce the amount of depression of the brake pedal, the diameter of the brake cylinder is reduced, the diameter of the master cylinder is increased, and the displacement of the brake pedal is transmitted to the master cylinder with a larger displacement than before (for example, the brake pedal). There is a means such as reducing the turning radius of. However, any of these means causes an increase in the pedal effort of the brake pedal. In addition, when the diameter of the master cylinder is increased, the sliding resistance of the piston built in the master cylinder increases, the hysteresis of the brake characteristic expands, and the operation feeling of the brake is impaired. That is, when the operation direction of the brake pedal is switched from the depression direction to the release direction, for example, the piston of the master cylinder is held in a fixed position by sliding resistance until the release amount of the pedal reaches a certain amount, and the braking force does not change. Therefore, there is a discrepancy between the brake characteristic when the brake pedal is depressed (the relationship between the depression amount and the braking force) and the brake characteristic when the brake pedal is loosened. The larger the deviation, the more difficult it becomes to adjust the braking force by a minute operation of the brake pedal, and the brake device becomes difficult for the operator to use.

According to the present invention, the operation stroke and operation force of the operation member such as the brake pedal can be kept small while expanding the operation stroke of the brake cylinder, and moreover, the hysteresis of the brake characteristic can be suppressed to provide a good operation feeling. It is an object of the present invention to provide a winch braking device obtained.

[0007]

When the invention of claim 1 is described in association with FIG. 1 showing an embodiment of the invention, a brake operating pressure Pout according to a braking operation of a brake operating member 11 is output. The master cylinder 10, the first brake cylinder 7 that operates in a direction to brake the winch winding drum 3 in response to the brake operating pressure Pout from the master cylinder 10, and the brake release pressure Pr introduced from the pressure source 14 decrease. Then, it is applied to a winch brake device including a second brake cylinder 8 that operates in a direction to brake the hoisting drum 3 and operates in a direction to release the braking of the hoisting drum 3 when the brake release pressure Pr increases. . The linking means 19 for reducing the brake release pressure Pr acting on the second brake cylinder 8 in cooperation with the braking operation of the brake operating member 11 is provided to achieve the above-mentioned object. The invention of claim 2 is applied to the winch brake device of claim 1, and the linkage means 19 limits the brake release pressure Pr only to the extent that the braking force by the first brake cylinder 7 exceeds a predetermined value (T2 in FIG. 4). Lower.
The invention according to claim 3 is applied to the winch brake device according to claim 2, and assist means for increasing the brake operating pressure Pout above the pressure (pressure according to the straight line L1 in FIG. 3) obtained by the operating force of the brake operating member 11. 13 and 14 are provided, and the brake operating pressure Pout is increased by the assisting means 13 and 14 at a stage (T1 in FIG. 4) before the braking force by the first brake cylinder 7 reaches the predetermined value (T2 in FIG. 4). Is configured to start. The invention of claim 4 is applied to the winch brake device of claim 2 or 3, wherein the predetermined value corresponds to a braking force (T2 in Fig. 4) required when a rated load is applied to the winding drum 3.

In the invention of claim 1, the brake operating member 1
When the brake operation 1 is performed, the brake operating pressure Pout corresponding to the operation is output from the master cylinder 10, and the first brake cylinder 7 operates in response to the operation pressure Pout to brake the hoisting drum 3. This braking mechanism corresponds to a so-called positive brake. The second brake cylinder 8 lowers the brake release pressure Pr and causes the hoist drum 3 to rotate.
Although a so-called negative brake is configured to brake the brake, the brake release pressure Pr is reduced even when the brake operating member 11 is braked by the action of the linking means 19. Therefore, by the braking operation of the brake operating member 11,
Not only the braking force of the first brake cylinder 7 but also the braking force of the second brake cylinder 8 acts on the winding drum 3. According to the second aspect of the present invention, even if the brake operating member 11 is brake-operated, the braking force by the second brake cylinder 8 does not act until the braking force by the first brake cylinder 7 reaches a predetermined value. When the braking force by the brake cylinder 7 exceeds the predetermined value, the braking force by the second brake cylinder 8 is added. According to the third aspect of the invention, when the brake operating member 11 is brake-operated, first, the assisting means 13 and 14 cause the first operation.
The braking force by the brake cylinder 7 is increased, and when the braking force exceeds a predetermined value, the braking force by the second brake cylinder 8 is added. In the invention of claim 4, when the load of the winding drum 3 is less than or equal to the rated load, the braking force by the second brake cylinder 8 does not act even if the brake operating member 11 is braked, and the winding drum 3
If the load exceeds the rated load, the second brake cylinder 8
The braking force by is added.

In the means and means for solving the above problems which explain the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a main part of a winch driving hydraulic circuit in which a brake device according to an embodiment of the present invention is incorporated. 1 is a hydraulic motor, 2 is a clutch cylinder, and 3 is a winch winding drum. When the oil chamber 2a of the clutch cylinder 2 is equal to the tank pressure, the spring 2b drives the piston rod 2c to the right in the figure to turn on the clutch, that is, the hydraulic motor 1 and the winding drum 3 are connected. When a predetermined clutch release pressure acts on the oil chamber 2a, the piston rod 2c moves to the left in the drawing against the spring 2b and the clutch is turned off, that is, the hydraulic motor 1 and the winding drum 3 are separated. Winding drum 3
For example, a hoisting rope (not shown) for raising and lowering the hook of the crane is wound up.

A brake band 4 is provided on the outer periphery of the hoisting drum 3, one end of which is connected to a bracket 5 protruding from a fixed portion of the crane body, and the other end of which is rotatably connected to the tip of a lever 6. There is. A lining material (not shown) having a high frictional resistance is appropriately attached to the inner circumference of the brake band 4. The lever 6 is provided so as to be rotatable about a shaft 6a, and its base end side includes a piston cylinder 7 as a brake cylinder and a piston rod 7 of a negative cylinder 8.
a and 8a are connected. When the lever 6 is driven in the direction of arrow B in the figure by these cylinders 7 and 8, the brake band 4 is tightened to brake the winding drum 3, and when the lever 6 is driven in the direction of arrow R, the winding drum 3 of the winding drum 3 moves. Braking is released. Reference numeral 9 is a spring that biases the lever 6 in the direction of arrow R.

The output pressure Pout of the bore side oil chamber 10a of the master cylinder 10 is introduced into the bore side oil chamber 7b of the positive cylinder 7. Piston rod 10b of master cylinder 10
Is the brake pedal 11 provided in the driver's seat of the crane.
Is connected via a link 12. Brake pedal 11
When is depressed, the piston rod 10b is displaced leftward in the drawing, the output pressure Pout of the bore side oil chamber 10a rises, and the braking force of the hoisting rod 3 by the positive cylinder 7 increases. Oil chamber 10 on the rod side of the master cylinder 10
The assist pressure Pa from the pressure reducing valve 13 is introduced to c. The pressure reducing valve 13 uses the secondary pressure (assist pressure Pa) of itself and the spring 13a to control the rod side oil chamber 10c and the tank 15.
And the output pressure Pout of the master cylinder 10 so that the hydraulic pump 14 and the rod-side oil chamber 10c communicate with each other. By adding the assist pressure Pa from the pressure reducing valve 13, the output pressure Pout of the master cylinder 10 becomes higher than the pressure obtained only by the pedal effort of the brake pedal 11. Here, the assist pressure Pa by the pressure reducing valve 13 is expressed by the following equation.

## EQU1 ## Pa = Pout-Psp (1) Psp is a set pressure by the spring 13a.

FIG. 3 shows the relationship between changes in the pedaling force F of the brake pedal 11 and the output pressure Pout when the above assist pressure Pa is applied. The straight line L1 in FIG. 3 is the assist pressure Pa.
Shows the output pressure when not applying, in other words, the pressure obtained only by the pedaling force F, and the solid line L2 shows the output pressure Pout when the assist pressure Pa is applied. In the range where the pedal effort F is smaller than the pedal effort F1 corresponding to the set pressure Psp by the spring 13a, the pressure reducing valve 13 is constrained to the b position and the assist pressure Pa escapes to the tank 15, so the output pressure Pout changes according to the straight line L1. However, when the output pressure Pout becomes equal to or higher than the set pressure Psp, the assist pressure Pa starts to increase, and the output pressure Pout becomes higher than the pressure (straight line L1) obtained by the pedaling force F.

The pressure supplied from the hydraulic pump 13 is Pp.
Then, the pedaling forces F1 and F2 when the output pressure Pout is Psp and Pp + Psp are as follows.

[Number 2] _{F1 = Psp × A B / L} F2 = {(Pp + Psp) × A B -Pp × A R} / L Note, A _B, A _R is the bore receiving area and the rod side of the master cylinder 10, respectively The pressure receiving area, L is the lever ratio of the brake pedal 11 (the amount of depression of the brake pedal 11 / the amount of movement of the piston rod 10b). Assist pressure Pa
Is the supply pressure Pp from the hydraulic pump 13, and the assist force Famax at that time is as follows.

## EQU3 ## Famax = Pamax × A _R = Pp × A _{R After the} assist force reaches Famax, the output pressure Pout increases depending only on the increase in the pedaling force F of the brake pedal 11.

Referring again to FIG. Negative cylinder 8
The piston rod 8a is always biased to the right in the figure (the direction in which the winding drum 3 is braked) by the spring 8b.
When a predetermined brake release pressure Pr is introduced into the oil chamber 8c, the piston rod 8a is displaced leftward in the figure against the spring 8b, and the braking of the hoisting drum 3 by the negative cylinder 8 is released.

Clutch cylinder 2 and negative cylinder 8
In order to control the operation of the above, in the hydraulic circuit of the present embodiment, the changeover valves 16 to 18, the pressure reducing valve 19, and the mode changeover switch 2
0 is provided. The switching valve 16 is switched to either the a position or the b position by the excitation and demagnetization of the solenoid portion 16a according to the ON / OFF of the mode changeover switch 20. The switching valves 17 and 18 switch between the a position and the b position according to the operating state of the operating lever 21 with respect to the hydraulic motor 1. That is, when the operation lever 21 is in the neutral position shown in the drawing, the secondary side of the pressure reducing valves 22 and 23 is the tank 15
The pilot pressure introduced from the pressure reducing valves 22 and 23 to the switching valves 17 and 18 via the shuttle valve 24 is reduced to the tank pressure, and the switching valves 17 and 18 are held at the illustrated position a. At this time, the control valve 25 of the hydraulic motor 1 is constrained to the neutral position where the hydraulic oil is confined in the hydraulic motor 1, whereby the hydraulic motor 1 is stopped. When the operation lever 21 is tilted from the neutral position to the left or right in the figure, the secondary pressure of the pressure reducing valve 22 or 23 increases according to the amount of operation. As a result, the control valve 25 is switched to start the rotation of the hydraulic motor 1, and the switching valves 17 and 18 are switched to the b position side shown in the figure.

In the pressure reducing valve 19, the output pressure Pout of the master cylinder 10 introduced as the pilot pressure of the pressure reducing valve 19 has a predetermined value Pn.
In the following range, the output pressure Pout is constrained at the illustrated position a.
Exceeds a predetermined value Pn, the output pressure out increases and b
Move gradually to the position side. This predetermined value Pn is the pressure reducing valve 1
Output pressure P when the assist pressure Pa due to 3 reaches the maximum
It is set somewhat lower than p + Psp (see FIGS. 3 and 4). The mode selector switch 20 can be operated by the operator in the driver's seat.

Next, the operation will be described. First, when the mode changeover switch 20 is turned off as shown in FIG. 1, the changeover valve 16 is restricted to the a position, and the changeover valve 17 is changed to the a position and the b position.
Oil chamber 2a of clutch cylinder 2 in any position
Communicate with the tank 15. Therefore, the clutch cylinder 2 is always in the clutch-on state in which the hydraulic motor 1 and the winding drum 3 are connected regardless of the operation of the operation lever 21. On the other hand, in the negative cylinder 8, when the switching valve 18 is in the a position, that is, when the operating lever 21 is in the neutral position, the oil chamber 8 of the negative cylinder 8 is in the a position or the b position.
c is maintained in a state of communicating with the tank 15 and braking the winding drum 3.

When the operating lever 21 is operated to drive the hydraulic motor 1 from the state shown in FIG. 1, the switching valve 18 is switched to the b position and the discharge pressure of the hydraulic pump 14 is guided from the switching valve 18 to the pressure reducing valve 19. Get burned. If the brake pedal 11 is not stepped on, the pressure reducing valve 19 is held in the a position, so that the discharge pressure of the hydraulic pump 14 is guided to the oil chamber 8c of the negative cylinder 8 as the brake release pressure Pr and the negative cylinder 8 causes the hoisting drum 3 to rotate. Braking is released. As a result, the winding drum 3 is driven by the hydraulic motor 1.

As shown in FIG. 2, the mode selector switch 2
When 0 is turned on, the switching valve 16 is switched to the b position, and the switching valve 16 switches the switching valves 17 and 18 to the hydraulic pump 14.
Discharge pressure is introduced. Therefore, the clutch cylinder 2
Is in a clutch-off state in which the hydraulic motor 1 and the winding drum 3 are disconnected when the switching valve 17 is in the a position, and is in a clutch-on state in the b position. In other words, the clutch is off when the operation lever 21 is in the neutral position, and the clutch is on when the operation lever 21 is operated to drive the hydraulic motor 1. Further, since the discharge pressure of the hydraulic pump 14 is guided to the pressure reducing valve 19 regardless of whether the switching valve 18 is in the a position or the b position, the negative cylinder 8 operates according to the position of the pressure reducing valve 19. Here, the pressure reducing valve 19 is held in the a position until the output pressure Pout of the master cylinder 10 reaches a predetermined value Pn (FIG. 4). Therefore, when the operation lever 21 is set to the neutral position and the brake pedal 11 is loosened, not only the braking of the hoisting drum 3 by the positive cylinder 7 is released, but also the brake release pressure P is applied to the oil chamber 8c of the negative cylinder 8.
The discharge pressure of the hydraulic pump 14 is guided as r, the braking of the winding drum 3 by the negative cylinder 8 is also released, and the winding drum 3 free falls.

To prevent the free fall, the brake pedal 11 is depressed to brake the winding drum 3. Here, the relationship between the output pressure Pout of the master cylinder 10 when the brake pedal 11 is depressed and the braking force acting on the winding drum 3 is as shown in FIG. The braking force is small in the initial stage when the output pressure Pout is less than the set pressure Psp by the spring 13a of the pressure reducing valve 13, but when the output pressure Pout becomes equal to or higher than the set pressure Psp, the assist pressure Pa is added to the master cylinder 10 and the brake pedal 11 is obtained only by the depression force. A braking force larger than the applied force acts on the hoisting drum 3. Assist pressure Pa
Approaches the limit value (the discharge pressure Pp of the hydraulic pump 14),
The pressure reducing valve 19 starts to move to the b position, and the brake release pressure Pr introduced into the oil chamber 8c of the negative cylinder 8 becomes the output pressure P.
The pressure is gradually reduced as out increases. As a result, the braking force of the negative cylinder 8 is added to the braking force of the positive cylinder 7, and the hoisting drum 3 is braked more strongly than when the positive cylinder 7 alone is used for braking. Therefore, if the maximum braking force Tmax is the same as the conventional one, the diameter of the positive cylinder 7 is smaller than that of the conventional example in which the hoisting drum 3 is braked only by the positive cylinder 7, and therefore, the master cylinder 10 while ensuring a sufficient stroke of the positive cylinder 7.
Therefore, the amount of oil to be supplied to the positive cylinder 7 can be reduced to reduce the diameter of the master cylinder 10 and the depression amount of the brake pedal 11.

Even when the mode selector switch 20 is on, when the operating lever 21 is operated from the neutral position, the clutch cylinder 2 is turned on and the hydraulic motor 1 is released in response to the release of the depression operation of the brake pedal 11.
The driving of the winding drum 3 is started.

Here, as shown in FIG. 4, the amount of change in the braking force acting on the winding drum 3 is defined by a point T1 at which the assist pressure Pa starts to rise and a point T2 at which braking by the negative cylinder 8 is started. Is different. The positions of the points T1 and T2 may be appropriately set according to the required braking force. For example, at the point T1, the play of the brake band 4 is zero, that is, the brake band 4 is in close contact with the hoisting drum 3 and is substantially in contact. Point T2
Is set to the braking force required when the rated load acts on the hoisting drum 3. With such a setting, the braking force of the negative cylinder 8 is used only when a load larger than the rated load acts on the hoisting drum 3, and as long as the load on the hoisting drum 3 is limited within the rated load. The winding drum 3 is braked only by the braking force strengthened by the assist pressure Pa, and during that period,
Since the braking force changes linearly with respect to the pedaling force of the brake pedal 11, the operation feeling is further improved together with the reduction in diameter of the master cylinder 10.

In the embodiment of the invention described above, the brake pedal 11 serves as the brake operating member, the output pressure Pout of the master cylinder 10 serves as the brake operating pressure, the positive cylinder 7 serves as the first brake cylinder, and the negative cylinder 8 serves as the second brake cylinder. The hydraulic pump 14 constitutes a pressure source for the second brake cylinder, the pressure reducing valve 19 constitutes a linking means, and the pressure reducing valve 13 and the hydraulic pump 14 constitute an assisting means. In the embodiment of the invention described above, the braking by the negative cylinder 8 is started when the braking force becomes considerably large. However, if the operation characteristic of the pressure reducing valve 19 is changed,
It is also possible to set to gradually increase the braking force by the negative cylinder 8 from the initial stage of the step of depressing the brake pedal 11. Output pressure Pout of master cylinder 10
Is not limited to the example in which the positive cylinder is directly guided to the positive cylinder 8, but a higher pressure is introduced to the positive cylinder 7 by guiding it to a booster cylinder or the like.
The present invention can be applied even in the case of leading to.

[0025]

As described above, according to the present invention,
Since the braking force of the negative brake system using the second brake cylinder is added when the hoisting drum is braked by the positive brake system using the first brake cylinder, the diameter of the first brake cylinder is made smaller than before. However, the required braking force is secured. By reducing the diameter of the first brake cylinder, the supply flow rate from the master cylinder is reduced while ensuring a sufficient stroke, the diameter of the master cylinder and the operation amount of the brake operating member are reduced, and the operating force of the brake operating member is also small. Can be kept. By reducing the diameter of the master cylinder, it is possible to suppress hysteresis of the brake characteristics and obtain a good operation feeling. Particularly, in the invention of claim 2, the braking force by the second brake cylinder can be added only in the region where the braking force by the first brake cylinder is insufficient. In the invention of claim 3, the assisting means boosts the brake operating pressure. The braking force of the second brake cylinder can be added only in the region where the braking force is insufficient while increasing the braking force of the positive brake, so that the master cylinder can be made sufficiently small to obtain an extremely good operation feeling. You can In the invention of claim 4, the shortage of the braking force by the first brake cylinder can be compensated by the braking force by the second brake cylinder only when a load exceeding the rated load is applied to the winding drum.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a winch driving hydraulic circuit in which a brake device according to an embodiment of the present invention is incorporated.

FIG. 2 is a diagram showing a state in which a winding drum is free-falling in the winch drive circuit of FIG.

FIG. 3 is a diagram showing a relationship between a pedal effort of a brake pedal and an output pressure of a master cylinder.

FIG. 4 is a diagram showing a relationship between an output pressure of a master cylinder and a braking force acting on a winding drum.

[Explanation of symbols]

 1 Hydraulic motor for driving winch 2 Clutch cylinder 3 Winding drum of winch 4 Brake band 7 Positive cylinder 8 Negative cylinder 10 Master cylinder 11 Brake pedal 13, 19 Pressure reducing valve 14 Hydraulic pump 20 Mode selector switch

Claims (4)

[Claims] 1. A master cylinder that outputs a brake operating pressure according to a braking operation of a brake operating member, and a first cylinder that operates in a direction to brake a winch winding drum in response to the brake operating pressure from the master cylinder. Brake cylinder and second brake cylinder that operates in a direction to brake the winding drum when the brake release pressure introduced from the pressure source decreases, and operates in a direction to release the braking of the winding drum when the brake release pressure increases. A winch brake device including: and a linking unit that links the brake operation of the brake operation member to reduce the brake release pressure acting on the second brake cylinder. Winch braking system. 2. The winch brake device according to claim 1, wherein the linking means reduces the brake release pressure only within a range in which the braking force of the first brake cylinder exceeds a predetermined value. 3. Assist means for increasing the brake operating pressure higher than the pressure obtained by the operating force of the brake operating member is provided, and at a stage before the braking force by the first brake cylinder reaches the predetermined value. The winch brake device according to claim 2, wherein the assisting means is configured to start increasing the brake operating pressure. 4. The winch brake device according to claim 2, wherein the predetermined value corresponds to a braking force required when a rated load is applied to the winding drum.