Brake device for winch and crane having the same

Abstract

To provide a brake device for a winch that is simpler in structure and can contribute to space saving.SOLUTION: A brake device for a winch includes a plurality of pedal units (50) provided in correspondence with a plurality of winches (105, 106). Each of the pedal units (50) includes: a brake pedal (51); a brake valve (6) that brakes the winch in conjunction with an operation of the brake pedal (51); and a brake characteristic setting mechanism (53) interposed between the brake pedal (51) and the brake valve (6). The brake characteristic setting mechanism (53) includes a cam plate (57) that sets a relation of an amount of displacement of a stroke of the brake valve (6) with the operation of the brake pedal (51).SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a winch braking device and a crane equipped with the same.

Background Art

[0002] As a background art in this technical field, for example, the winch braking device described in Patent Document 1 includes a brake for braking a winch drum, a brake pedal disposed so as to be depressible with respect to a vehicle body, a reaction force applying element for applying a reaction force to the brake pedal, a rotation link that rotates in conjunction with the depression operation of the brake pedal, a brake control valve that is connected to the rotation link and causes a secondary pressure to act on the brake in response to the depression operation of the brake pedal, a tension spring having one end attached to the vehicle body and the other end attached to the rotation link, and biasing the brake pedal in a direction opposite to the depression operation direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The load applied to the winch during crane operation varies depending on the work content and also on the weight of the suspended load. Therefore, from the viewpoint of workability, it is preferable to set the braking characteristics (i.e., brake characteristics) of the optimal winch braking device according to the crane operation. However, since the winch braking device described in Patent Document 1 has a configuration including a link mechanism, when attempting to change the brake characteristics, the link mechanism becomes complicated. Moreover, when the link mechanism becomes complicated, space is also required accordingly.

[0005] Therefore, the main object of the present invention is to provide a winch braking device that is simpler in structure and can contribute to space saving.

Means for Solving the Problems

[0006] To achieve the above object, a typical aspect of the present invention is a winch braking device mounted on a crane, comprising a plurality of winches and a plurality of pedal units provided corresponding to each of the plurality of winches, wherein each pedal unit includes a pedal, a brake valve that applies braking to the winch in conjunction with the operation of the pedal, and a brake characteristic setting mechanism interposed between the pedal and the brake valve, and the brake characteristic setting mechanism includes a cam plate that sets the relationship of the displacement amount of the stroke of the brake valve with respect to the operation of the pedal.

[0007] According to the present invention, it is possible to obtain a winch braking device that is simpler in structure and can contribute to space saving, and a crane equipped with the same. In addition, problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of a crane according to the present invention will be described with reference to the drawings.

[0010] FIG. 1 is a side view of a crane 100 equipped with a braking device according to an embodiment. The crane 100 is a crawler crane and has a traveling body 101, a revolving body 103 rotatably provided on the traveling body 101 via a slewing ring 102, and a boom 104 rotatably supported by the revolving body 103. The traveling body 101 has a truck frame 101a and crawlers 101b attached to the truck frame 101a.

[0011] The revolving body 103 is provided with a driver's cab 109, and in addition to an engine 107 which is a prime mover, a winch 105 for hoisting and a winch 106 for boom raising and lowering are mounted. A hoisting rope 105a is wound around the hoisting winch 105, and the hoisting rope 105a is wound up or paid out by driving the hoisting winch 105, and the hook 110 is raised and lowered. A raising and lowering rope 106a is wound around the raising and lowering winch 106, and the raising and lowering rope 106a is wound up or paid out by driving the raising and lowering winch 106, and the boom 104 is raised and lowered.

[0012] The slewing body 103 is slewing-driven by a slewing hydraulic motor (not shown) via a slewing ring 102, the hoisting winch 105 is driven by a hoisting hydraulic motor (see FIG. 3), and the luffing winch 106 is driven by a luffing hydraulic motor (not shown).

[0013] FIG. 2 is a perspective view showing the entirety of the driver's cab 109. As shown in FIG. 2, the driver's cab 109 is provided with a driver's seat 201 on which an operator sits, a right lever group (travel lever, hoisting operation lever 13, etc.) 210 that is operated by the operator sitting on the driver's seat 201 with the right hand, and a left lever (slewing lever) 221 that is operated by the operator sitting on the driver's seat 201 with the left hand. Further, a display device 231 is provided at the left front of the driver's seat 201, and various information such as the operating state and warnings of the crane 100 is displayed thereon.

[0014] On the floor of the driver's cab 109, a hoisting drum brake pedal 251 for braking the hoisting winch 105, a rear drum brake pedal 252 for braking the luffing winch 106, an accelerator pedal 261 for increasing or decreasing the rotational speed of the engine 107, and a slewing brake pedal 262 for braking the slewing body 103 are provided.

[0015] The hoisting drum brake pedal 251 is an example of a brake pedal provided in a brake device for braking the hoisting winch 105. That is, the hoisting drum brake pedal 251 receives a stepping operation by the operator. Then, according to the depression amount (operation amount) of the hoisting drum brake pedal 251 by the operator, the braking force (operation amount) of the hoisting winch 105 is adjusted. That is, in order to brake the hoisting winch 105 with a desired braking force, it is necessary to accurately detect the depression amount of the hoisting drum brake pedal 251.

[0016] Note that the brake device according to the present embodiment is applied to a pedal unit 50 including the hoisting drum brake pedal 251, but is similarly applied to a pedal unit including the rear drum brake pedal 252.

[0017] FIG. 3 is a hydraulic circuit diagram of the braking device according to the present embodiment. In FIG. 3, a hydraulic circuit for driving the hoisting winch 105 is illustrated, and a hydraulic circuit for driving the luffing winch 106 is omitted from illustration.

[0018] The crane 100 includes a controller 18 that controls the operations of each part of the crane 100, an engine (not shown), a main pump 12, a cooling oil pump 19, and a pilot pump 9 that are driven by the engine (not shown). The main pump 12, the cooling oil pump 19, and the pilot pump 9 discharge the hydraulic oil in the tank 10 as pressure oil.

[0019] The controller 18 includes, although not shown, a CPU that performs various operations and the like, a storage device such as a ROM or an HDD that stores programs for executing operations by the CPU, a RAM that serves as a work area when the CPU executes programs, and hardware including a communication interface that is an interface for transmitting and receiving data to and from other devices, and software stored in the storage device and executed by the CPU. Each function of the controller 18 is realized by the CPU loading various programs stored in the storage device into the RAM and executing them.

[0020] The hoisting winch 105 includes a winding drum 3, a hydraulic motor 1, a main pump 12, a control valve 11, a planetary reduction mechanism 2, and a brake 4. The main pump 12 supplies pressure oil to the hydraulic motor 1, drives the hydraulic motor 1, and drives the winding drum 3 for hoisting and lowering. The control valve 11 controls the flow of pressure oil from the main pump 12 to the hydraulic motor 1. The planetary reduction mechanism 2 transmits the driving force of the hydraulic motor 1 to the winding drum 3. The brake 4 prevents the free rotation of the winding drum 3 by braking the carrier shaft 4f of the planetary reduction mechanism 2.

[0021] The planetary reduction mechanism 2 is composed of a sun gear 2a, planetary gears 2b, and a ring gear 2c. The output shaft of the hydraulic motor 1 is connected to the sun gear 2a of the planetary reduction mechanism 2. Planetary gears 2b are meshed with the sun gear 2a, and a ring gear 2c provided on the inner circumferential side of the winding drum 3 is meshed with the planetary gears 2b. The planetary gears 2b are supported by a planetary carrier 2d. A carrier shaft 4f to which the planetary carrier 2d is fixed is supported by bearings inside the brake 4.

[0022] The brake 4 also has a function as a clutch device that transmits or cuts off rotation between the hydraulic motor 1 and the winding drum 3. That is, the brake 4 functions as a clutch and a parking brake during power winding and stopping, and has a function as a service brake (normal brake) during free fall.

[0023] The brake 4 applied to this embodiment is of the negative type and is a wet multi-plate brake having a plurality of inner disks (friction plates) 4a. The brake 4 includes a plurality of inner disks 4a housed in a brake case 4e, a plurality of outer disks 4b, a brake disk 4c, and a spring 4d. The inner disks 4a are axially movably engaged with the carrier shaft 4f by spline connection, and the inner disks 4a and the carrier shaft 4f can rotate integrally. The outer disks 4b are axially movably engaged with the inner circumferential surface of the brake case 4e by spline connection.

[0024] The outer disks 4b and the inner disks 4a are arranged alternately in the axial direction. A brake disk 4c is arranged on the axially lateral side of the end of the carrier shaft 4f. A spring 4d is arranged between the brake disk 4c and the brake case 4e.

[0025] A biasing force of a spring 4d always acts on a brake disk 4c so as to press an inner disk 4a and an outer disk 4b together. Inside a brake case 4e, a brake cylinder having the brake disk 4c as a piston is formed by the brake disk 4c, an oil chamber 4g, and the spring 4d. When no hydraulic pressure acts on the oil chamber 4g, the brake disk 4c is pushed in the direction of A shown in the figure by the biasing force of the spring 4d. As a result, a frictional force acts on the surface of the inner disk 4a, and the rotation of the inner disk 4a is blocked.

[0026] Further, when pressure oil is supplied from a hydraulic circuit described later to the oil chamber 4g, a hydraulic pressure (brake release pressure) that resists the biasing force of the spring 4d acts on the brake disk 4c, and the brake disk 4c is pushed in the direction of B shown in the figure. As a result, the pressing contact force between the inner disk 4a and the outer disk 4b is removed, and the carrier shaft 4f becomes rotatable.

[0027] Here, in order to cool the brake 4, cooling oil (pressure oil) is forcibly circulated by a cooling oil pump 19. Specifically, the cooling oil discharged from the cooling oil pump 19 is supplied into the brake 4 from the IN port of the oil chamber 4g, absorbs the heat of the brake disk (inner disk 4a and outer disk 4b), and then is discharged from the OUT port of the oil chamber 4g and returns to the tank 10. The upper limit of the discharge pressure of the cooling oil pump 19 is limited by a casing internal pressure protection valve 20 which is a relief valve. Therefore, the internal pressure of the brake 4 is also maintained below the upper limit of the casing internal pressure protection valve 20.

[0028] A hydraulic circuit for driving a hoisting winch 105 is provided with a motor brake switching valve 7 that is switched and controlled by an operation of a hoisting operation lever 13 (right lever group 210), a motor brake cylinder 8, a brake valve 6 that is operated by a brake pedal 51 of a pedal unit 50, an electromagnetic switching valve 5 that is switched and controlled by a controller 18, and a casing internal pressure protection valve 20.

[0029] In addition, this hydraulic circuit is provided with a plurality of operation pressure sensors 15 and one brake circuit pressure sensor 16 to switch the electromagnetic switching valve 5 to switch the operation mode of the brake 4 (brake mode / free mode), and they are respectively connected to the controller 18. Further, a brake mode switching switch 17 is connected to the controller 18. The brake mode switching switch 17 is a switch for selecting whether the operation mode of the brake 4 is in the brake mode or the free mode.

[0030] When the hoisting operation lever 13 shown in FIG. 3 is operated to the hoisting position or the lowering position, the pilot pressure from the pilot pump 9 acts on the control valve 11 to drive the spool of the control valve 11, and the pressure oil discharged from the main pump 12 is supplied to the hydraulic motor 1 through the control valve 11. At the same time, the pilot pressure from the pilot pump 9 also acts on the motor brake switching valve 7 through the high-pressure selection valve 14. As a result, the motor brake switching valve 7 is switched to the position (A), and the pilot pressure from the pilot pump 9 drives the motor brake cylinder 8 to the brake release side, so that the hydraulic motor 1 is rotationally driven.

[0031] The brake valve 6 is a pressure reducing valve and is provided with a push rod 6a that strokes according to the operation amount of the brake device. The secondary pressure of the pressure oil passing through the brake valve 6, that is, the brake release pressure, becomes smaller as the push rod 6a is pushed into the brake valve 6.

[0032] A brake characteristic setting mechanism 53 that transmits the pedal stepping force generated when the brake pedal 51 of the pedal unit 50 is stepped on to the brake valve 6 is connected to the push rod 6a of the brake valve 6. The brake characteristic setting mechanism 53 will be described in detail later. However, the push rod 6a strokes in conjunction with the stepping operation of the brake pedal 51, and the degree of pressure reduction of the brake valve 6 is determined according to the stroke amount. Therefore, when the brake pedal 51 is stepped on, the secondary pressure corresponding to the operation amount acts on the brake 4, and a braking force corresponding to the operation amount is generated.

[0033] The electromagnetic switching valve 5 is switched between a brake mode and a free mode by operating the brake mode changeover switch 17. When the brake mode changeover switch 17 is turned on, it switches to position (C), and when it is turned off, it switches to position (D). The switching between the brake mode and the free mode is performed by operating the electromagnetic switching valve 5 according to a command from the controller 18 based on the respective determination values of the operation pressure sensor 15, the brake circuit pressure sensor 16, and the brake mode changeover switch 17.

[0034] Figure 3 shows the state in the brake mode. In the brake mode, the electromagnetic switching valve 5 is in a non-excited state. Therefore, the electromagnetic switching valve 5 has switched to position (D). The pilot pressure from the pilot pump 9, which is the brake release pressure, is blocked by the electromagnetic switching valve 5, and the oil chamber 4g of the brake 4 communicates with the tank 10 and becomes the tank pressure. When the oil chamber 4g reaches the tank pressure, the brake disk 4c is pushed in the direction shown by A in the figure by the biasing force of the spring 4d. Therefore, the inner disk 4a and the outer disk 4b are pressed against each other, and a braking force is applied to the carrier shaft 4f, and the carrier shaft 4f is fixed.

[0035] In the brake mode, when the sun gear 2a of the planetary reduction mechanism 2 rotates by the rotational driving force of the hydraulic motor 1, the planetary gear 2b rotates, and the ring gear 2c and the winding drum 3 connected to the ring gear 2c rotate, and winding or unwinding by power is performed.

[0036] When the brake mode switching switch 17 is switched to the operation position of the free mode, the electromagnetic switching valve 5 is excited, and the operation mode is switched to the free mode. In the free mode, the electromagnetic switching valve 5 is in the excited state and switches to the position (C). Then, the pilot pressure (pilot pressure corresponding to the depression amount of the brake pedal 51) adjusted by the brake valve 6 is applied to the electromagnetic switching valve 5, and this pilot pressure acts on the oil chamber 4g of the brake 4. Therefore, a pressing force corresponding to the difference between the biasing force of the spring 4d and the pilot pressure acting on the oil chamber 4g acts on the brake disc 4c, and the brake disc 4c is pushed in the direction of B shown in the figure. As a result, the pressure contact force between the inner disc 4a and the outer disc 4b is removed, and the carrier shaft 4f becomes rotatable.

[0037] As described above, the secondary pressure (brake release pressure) of the pressure oil passing through the brake valve 6 becomes smaller as the push rod 6a is pushed into the brake valve 6. Therefore, in the free mode, the braking force (operation amount) of the hoisting winch 105 is adjusted according to the depression amount (operation amount) of the brake pedal 51 by the operator.

[0038] Next, the pedal unit 50 of the brake device according to the present embodiment will be described with reference to FIGS. 4 to 11.

[0039] FIG. 4 is a perspective view of a pedal unit 50 provided in the brake device according to the present embodiment, FIG. 5 is a side view of the pedal unit 50, FIG. 6 is a perspective view of a brake characteristic setting mechanism 53 provided in the pedal unit 50, FIG. 7 is a front view of a cam plate 57 provided in the brake characteristic setting mechanism 53, FIG. 8 is a side view of the pedal unit 50 showing the state before the brake pedal 51 is depressed, and FIG. 9 is a side view of the pedal unit 50 showing the state during the depression of the brake pedal 51. Further, FIG. 10 is a perspective view showing an operation of changing the engagement position of the cam plate 57, and FIG. 11 is a side view of the pedal unit 50 after the engagement position of the cam plate 57 is changed.

[0040] As shown in FIGS. 4 to 9, the pedal unit 50 mainly includes a brake pedal 51, a pedal lever 52 that rotates in conjunction with the operation of the brake pedal 51, a brake valve 6 that applies braking to the hoisting winch 105 in conjunction with the pedal lever 52, and a brake characteristic setting mechanism 53 interposed between the pedal lever 52 and the brake valve 6.

[0041] The pedal lever 52 is a long member that rotates (swings) by a stepping operation by the operator. A brake pedal 51 that receives the stepping operation by the operator is fixed to one end (upper end) of the pedal lever 52. Further, a cylindrical shaft portion 54 is provided at the other end of the pedal lever 52, and this shaft portion 54 is inserted into a fixed shaft 56 provided on a pedal bracket 55, which will be described later, of the brake characteristic setting mechanism 53. That is, the pedal lever 52 is rotatably supported by the fixed shaft 56 with the axis of the shaft portion 54 as the rotation center. Further, one key groove 54a is formed on the outer peripheral surface of the shaft portion 54.

[0042] The brake characteristic setting mechanism 53 mainly includes a pedal bracket 55, a cam plate 57, a cam follower 58, and an intermediate lever 59. The pedal bracket 55 has an L-shaped bracket body 55a, a mounting plate 55b provided at a corner portion of the bracket body 55a, and a pair of side plates 55c hanging down from the front side of the bracket body 55a. The upper surface plate extending in the horizontal direction of the bracket body 55a is disposed on the floor surface of the driver's cab 109, and the brake valve 6 is attached to the rear surface plate hanging down from the upper surface plate of the bracket body 55a.

[0043] An intermediate lever 59 is rotatably supported by a support shaft 64 on a mounting plate 55b of a pedal bracket 55, and a cam follower 58 is provided on one end side of the intermediate lever 59. One end portion of a connecting bar 65 is pivotally supported on the other end side of the intermediate lever 59, and the other end portion of the connecting bar 65 is connected to a push rod 6a of a brake valve 6. Further, a tension coil spring 60 is stretched between a side plate 55c of the pedal bracket 55 and a lower end portion of the pedal bracket 55, and the pedal bracket 55 is biased in the counterclockwise direction in FIG. 5 by the spring force of the tension coil spring 60.

[0044] The cam plate 57 is a member that sets the relationship between the displacement amount of the stroke of the brake valve 6 with respect to the operation (unit operation amount) of the brake pedal 51. In other words, the cam plate 57 is a member that varies the lever ratio defined by the displacement amount of the stroke of the brake valve 6 with respect to the operation of the pedal lever 52. As shown in FIG. 7, two cam curve portions (a first cam curve portion S1 and a second cam curve portion S2) are formed at different positions in the circumferential direction on the outer peripheral surface of the cam plate 57, and these first cam curve portion S1 and second cam curve portion S2 have shapes corresponding to the predetermined lever ratios, respectively.

[0045] The cam plate 57 has a mounting hole 57a supported by a shaft portion 54 of the pedal lever 52 and is an exchange member that can be attached to and detached from the pedal lever 52. Two key grooves (a first key groove 57b and a second key groove 57c) are formed at different positions along the circumferential direction on the outer edge portion of the mounting hole 57a. The cam plate 57 is rotatably supported by the shaft portion 54 of the pedal lever 52, but is fixed at a predetermined mounting angle with respect to the shaft portion 54 by inserting a key 61 between the first key groove 57b of the cam plate 57 and a key groove 54a formed in the shaft portion 54.

[0046] Incidentally, the mounting angle of the cam plate 57 with respect to the shaft portion 54 can be changed. By opposing the second key groove 57c of the cam plate 57 to the key groove 54a of the shaft portion 54 and inserting a key 61 between these second key groove 57c and key groove 54a, the cam plate 57 can be fixed to the shaft portion 54 at another mounting angle. That is, the key groove 54a of the shaft portion 54, the two key grooves 57b, 57c of the cam plate 57, and the key 61 constitute an engaging means capable of changing the engagement position of the cam plate 57 with respect to the pedal lever 52. Further, as shown in FIG. 6, a stop plate 62 that abuts against one end of the key 61 is attached to the shaft portion 54 of the pedal lever 52 using a screw 63. This stop plate 62 prevents the key 61 from falling out of the key groove 54a.

[0047] The cam plate 57 is fixed to the shaft portion 54 so that the rotation center coincides with that of the pedal lever 52 and rotates integrally with the pedal lever 52. The cam follower 58 is in contact with either one of the two cam curve portions S1, S2 of the cam plate 57. When the cam plate 57 rotates integrally with the pedal lever 52, the contact position between the cam follower 58 and the corresponding cam curve portion (S1 or S2) changes accordingly. Specifically, when the first key groove 57b of the cam plate 57 is engaged with the key groove 54a of the shaft portion 54 via the key 61, as shown in FIGS. 8 and 9, the cam follower 58 moves on the first cam curve portion S1 as the cam plate 57 rotates. Also, when the engagement position of the cam plate 57 with respect to the pedal lever 52 is changed and the second key groove 57c of the cam plate 57 is engaged with the key groove 54a of the shaft portion 54 via the key 61, the cam follower 58 moves on the second cam curve portion S2 as the cam plate 57 rotates (see FIG. 11). The procedure for changing the engagement position of the cam plate 57 will be described later.

[0048] As shown in FIG. 8, in the state before the brake pedal 51 is depressed, the pedal bracket 55 is pushed in the counterclockwise direction in FIG. 8 under the biasing force of the tension coil spring 60, and the cam follower 58 is in contact with a predetermined position (starting point) of the first cam curve portion S1 formed on the cam plate 57.

[0049] When the operator depresses the brake pedal 51 in this state, the pedal bracket 55 rotates (swings) in the clockwise direction of FIG. 8 around the fixed shaft 56, and the cam plate 57 also rotates in the same direction around the fixed shaft 56 integrally with the pedal lever 52. As a result, as shown in FIG. 9, the cam follower 58 provided at one end side of the intermediate lever 59 moves from the starting point to the ending point on the first cam curve portion S1 of the cam plate 57, and accordingly, the intermediate lever 59 rotates counterclockwise in FIG. 9 around the support shaft 64. As a result, the push rod 6a of the brake valve 6 is driven by the connecting bar 65 pivotally supported on the other end side of the intermediate lever 59. In this case, the stroke amount of the push rod 6a is displaced based on the lever ratio defined by the first cam curve portion S1 with respect to the depression amount of the brake pedal 51. As described above, the degree of pressure reduction of the brake valve 6 is determined according to the stroke amount of the push rod 6a (see FIG. 3). As the protruding amount of the push rod 6a increases, the hydraulic pressure acting on the oil chamber 4g of the brake 4 decreases, and the braking force increases.

[0050] When the brake pedal 51 is depressed in this way, the cam follower 58 that contacts the first cam curve portion S1 of the cam plate 57 also swings along with the swinging motion of the intermediate lever 59. Therefore, an offset amount with respect to the rotation center axis of the cam plate 57 is generated by the swinging motion of the cam follower 58. In the present embodiment, the cam follower 58 is arranged so that this set amount becomes as small as possible, and thus a smooth cam operation is performed. Specifically, the center of the cam follower 58 at the starting point of the first cam curve portion S1 shown in FIG. 8 and the center of the cam follower 58 at the ending point of the first cam curve portion S1 shown in FIG. 9 are both located on a vertical line passing through the rotation center of the cam plate 57.

[0051] As described above, the cam plate 57 can change the engagement position with respect to the pedal lever 52. By changing the engagement position of the cam plate 57 with respect to the pedal lever 52, the cam follower 58 can be selectively brought into contact with either the first cam curve portion S1 or the second cam curve portion S2 of the cam plate 57.

[0052] Next, with reference to FIGS. 10 and 11, the operation procedure for changing the engagement position of the cam plate 57 will be described.

[0053] When changing the portion where the cam follower 58 abuts from the first cam curve portion S1 to the second cam curve portion S2 of the cam plate 57, first, loosen the screw 63 to remove the retaining plate 62 from the shaft portion 54, and remove the key 61 from the first key groove 57b of the cam plate 57 and the key groove 54a of the shaft portion 54. As a result, the cam plate 57 becomes rotatable with respect to the shaft portion 54. Therefore, as shown in FIG. 10, rotate the cam plate 57 around the shaft portion 54 so that the second key groove 57c faces the key groove 54a. In this state, by inserting the key groove 54a between the second key groove 57c and the key groove 54a, after fixing the cam plate 57 to the shaft portion 54, fix the retaining plate 62 to the shaft portion 54 using the screw 63. As a result, as shown in FIG. 11, the cam follower 58 can be brought into contact with the second cam curve portion S2 of the cam plate 57.

[0054] As shown in FIG. 11, in the form where the cam follower 58 is in contact with the second cam curve portion S2 of the cam plate 57, when the operator depresses the brake pedal 51, the cam follower 58 moves on the second cam curve portion S2. In this case, the stroke amount of the push rod 6a of the brake valve 6 is displaced based on the lever ratio defined by the second cam curve portion S2 with respect to the depression amount of the brake pedal 51.

[0055] The operation of changing the engagement position of the cam plate 57 described above can be performed while the cam plate 57 is mounted on the shaft portion 54 without removing it from the pedal lever 52. Further, the first key groove 57b and the second key groove 57c of the cam plate 57 and the key groove 54a of the shaft portion 54 can be used as marks indicating the engagement position of the cam plate 57 with respect to the pedal lever 52, so that the cam plate 57 can be easily aligned. Note that alignment marks such as imprints may be provided separately on each of the cam plate 57 and the pedal lever 52.

[0056] Here, in the crane 100 equipped with the braking device according to the present embodiment, a plurality of winches (drums) are used, including a hoisting winch 105 which is a winch for hoisting and a boom hoisting winch 106 which is a winch for boom hoisting. The loads applied to these multiple winches change depending on the work content and also on the load of the suspended load. Therefore, the control characteristics of the pedal required for the braking device that brakes each winch are not uniform, and in order to improve the operability, it is preferable to give different control characteristics to the pedals of each braking device. Also, for the foot brake of the crane, the adjustment range of the braking force is wide from light load to heavy load. In order to obtain good operability on top of that, the characteristics are relaxed and a wide adjustment range is allocated during light load, and the characteristics are made steeper and a large braking force is obtained with a small adjustment range during heavy load, which is desirable for the characteristics. Furthermore, the control characteristics appropriate for the working conditions vary depending on the type of work and the preference of the operator. In view of such circumstances, in the present embodiment, by forming a plurality of types of cam curve portions on the cam plate 57, it is possible to select a pedal lever ratio according to the working characteristics.

[0057] FIG. 12 is an explanatory diagram showing the relationship between the pedal angle of the brake pedal 51 and the stroke amount of the brake valve 6 (push rod 6a).

[0058] Generally, a braking device has a "braking region" where a pressing member is brought into contact with a friction generating member to generate a braking force, and a "release region" where the pressing member is separated from the friction generating member to idle. In the "release region", it is necessary to separate the pressing member from the friction generating member by a predetermined amount so as to minimize the idle torque (drag resistance) of the braking device. In particular, in a wet multi-plate braking device, this separation amount (backstroke) is designed to be relatively large. As shown in FIG. 3, in a negative-type braking device that presses the pressing member by a spring force, the "release region" is also allocated to the pedal depression amount, so the pedal depression amount from the initial position of the brake pedal to the "braking region" becomes the "play region".

[0059] In the braking device according to this embodiment, there is "play" from the start of pressure control by the brake valve 6 until the braking force is output, and the vicinity of the initial depression of the brake pedal 51 becomes a "play area" where no braking force is output. In FIG. 12, the stroke amount of the push rod 6a is in the "play area" until it reaches around 0 to 2, and when the stroke amount of the push rod 6a reaches around 2, the output of the braking force starts.

[0060] In FIG. 12, reference numeral (1) indicates a linear characteristic, reference numeral (2) indicates a quadratic-curve non-linear characteristic, and reference numeral (3) indicates a cubic-curve non-linear characteristic. The linear characteristic (1) is a characteristic in which the stroke amount (lift-up amount) of the push rod 6a changes with a constant slope as the pedal angle increases (unit operation amount of the brake pedal 51), that is, a characteristic in which the braking force changes linearly according to the depression amount of the brake pedal 51. The non-linear characteristic (2) is a characteristic in which the stroke amount of the push rod 6a changes in a quadratic curve as the pedal angle increases, and since the start point of the braking force output is on the deeper side of the pedal angle (around 8°), the effective pedal stroke is reduced by that amount.

[0061] The non-linear characteristic (3) is a characteristic in which the stroke amount of the push rod 6a changes in a cubic curve as the pedal angle increases, and since the starting point of the braking force output is on the front side of the pedal angle (around 4°), a decrease in the effective pedal stroke can be suppressed. And this cubic curve non-linear characteristic (3) has a first region (pedal angle 4° to around 10°) where the slope of the stroke amount (valve stroke) of the push rod 6a with respect to the pedal angle (unit operation amount of the brake pedal 51) after the braking force output gradually becomes smaller, and a second region (pedal angle 10° or more) where the slope of the stroke amount of the push rod 6a with respect to the pedal angle becomes larger thereafter. Therefore, while flattening the slope of the braking characteristic during light load and allocating a wide adjustment range, a large braking force can be obtained with a small adjustment range by raising the slope of the braking characteristic during heavy load. Also, this cubic curve non-linear characteristic (3) has a third region where the slope of the stroke amount of the push rod 6a with respect to the pedal angle before the brake output (pedal angle 4° or less) gradually becomes larger. The slope of the non-linear characteristic (3) in this third region is larger than that in the first region and smaller than that in the second region. Therefore, a large stroke amount of the push rod 6a with respect to the unit operation amount (pedal angle) of the brake pedal 51 can be obtained at the initial movement of the pedal operation, then it is flattened (the stroke amount per unit operation amount is made smaller), and then raised (the stroke amount per unit operation amount is made larger), giving it a characteristic like a cubic curve.

[0062] Note that in this embodiment, the cam shape corresponding to the cubic curve non-linear characteristic (3) is formed in the first cam curve portion S1 of the cam plate 57, and the cam shape corresponding to the linear characteristic (1) is formed in the second cam curve portion S2 of the cam plate 57. However, the combination of cam shapes in the cam plate 57 is not limited to this. For example, a cam shape corresponding to a quadratic curve non-linear characteristic (2) may be formed in the second cam curve portion S2 instead of the linear characteristic (1), or a cam shape corresponding to a non-linear characteristic such as a quartic curve may be used. Also, the number of cam curve portions formed in the cam plate 57 is not limited to two, and one or three or more cam curve portions may be formed in the cam plate 57, or a plurality of cam curve portions having the same shape may be formed in the cam plate 57.

[0063] As described above, in the brake device of the winch according to the present embodiment, a plurality of pedal units 50 provided corresponding to each of the plurality of winches 105 and 106 include a brake pedal 51, a brake valve 6 that applies braking to the winch in conjunction with the operation of the brake pedal 51, and a brake characteristic setting mechanism 53 interposed between the brake pedal 51 and the brake valve 6. Since the brake characteristic setting mechanism 53 includes a cam plate 57 that sets the relationship of the displacement amount of the stroke of the brake valve 6 with respect to the operation of the brake pedal 51, the lever control characteristic ratio can be easily changed according to the cam shape of the cam plate 57, and a winch brake device with a simpler structure and more space-saving can be realized.

[0064] In addition, since the pedal unit 50 includes a pedal lever 52 that rotates in conjunction with the operation of the brake pedal 51, and the cam plate 57 is configured as a detachable replacement member with respect to the pedal lever 52, it is possible to easily vary the displacement amount of the stroke of the brake valve 6 with respect to the operation amount of the brake pedal 51 by simply replacing the cam plate 57. Note that detachable means excluding irreversible removal such as damage during removal by press-fitting or welding.

[0065] In addition, the cam plate 57 is fixed to the shaft portion 54 so that the rotation center coincides with the pedal lever 52 and rotates integrally with the pedal lever 52, so that the structure is simple and the number of parts can be reduced.

[0066] In addition, the cam plate 57 has a first cam curve portion S1 and a second cam curve portion S2 at different positions in the circumferential direction, and these first cam curve portion S1 and second cam curve portion S2 are respectively set in the predetermined relationship (the relationship of the displacement amount of the stroke of the brake valve 6 with respect to the operation of the brake pedal 51). Therefore, the brake characteristics can be easily changed according to the plurality of cam curve portions S1 and S2. Note that the number of cam curve portions formed on the cam plate 57 is not limited to two, and three or more cam curve portions may be formed on the cam plate 57.

[0067] In addition, an engaging means for changing the engaging position of the cam plate 57 with respect to the pedal lever 52 is provided, and since a plurality of cam curve portions S1, S2 and the engaging position of the cam plate 57 are associated with each other in advance, the braking characteristics can be easily changed by changing the engaging position of the pedal lever 52 and the cam plate 57. As such an engaging means, key fastening, spline fastening, or the like can be used.

[0068] Further, the pedal lever 52 has a shaft portion 54 that rotatably supports the cam plate 57, and the engaging means includes a first key groove 57b and a second key groove 57c provided in the cam plate 57, a key groove 54a provided in the shaft portion 54 of the pedal lever 52, and a detachable key 61 that selectively connects between these key grooves 54a, 57b, and 57c. Therefore, the engaging position of the cam plate 57 with respect to the pedal lever 52 can be changed while the cam plate 57 is mounted on the shaft portion 54 without removing the cam plate 57 from the pedal lever 52.

[0069] Moreover, the first key groove 57b and the second key groove 57c of the cam plate 57 and the key groove 54a of the shaft portion 54 can be used as marks indicating the engaging position of the cam plate 57 with respect to the pedal lever 52, so that the cam plate 57 can be easily aligned. Note that alignment marks made of engraving or the like may be separately provided on each of the cam plate 57 and the pedal lever 52.

[0070] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention. All technical matters included in the technical idea described in the claims are the subject of the present invention. The above embodiments show preferred examples, but those skilled in the art can realize various alternative examples, modification examples, variation examples, or improvement examples from the content disclosed in this specification, and these are included in the technical scope described in the appended claims.

[0071] For example, the winch brake device according to the present invention can also be applied to a crane equipped with a third winch in addition to the hoisting winch 105 which is a winch for hoisting and the luffing winch 106 which is a winch for luffing the boom. Here, as the third winch, for example, it is a winch for luffing the jib boom in a tower crane, a supplementary winding winch for hoisting an auxiliary hook, or the like. When the third winch is mounted, different braking characteristics are required compared to the hoisting winch 105 and the luffing winch 106. By applying the winch brake device according to the present invention, suitable braking characteristics for the third winch can be easily realized.

Explanation of Signs

[0072] 4 Brake 4a Oil Chamber 5 Electromagnetic Changeover Valve 6 Brake Valve 6a Push Rod 50 Pedal Unit 51 Brake Pedal (Pedal) 52 Pedal Lever 53 Brake Characteristic Setting Mechanism 54 Shaft Portion 54a Keyway 55 Pedal Bracket 57 Cam Plate 57a Mounting Hole 57b First Keyway 57c Second Keyway 58 Cam Follower 59 Intermediate Lever 61 Key 62 Stop Plate 65 Connecting Bar 100 Crane 105 Hoisting Winch 106 Luffing Winch S1 First Cam Curve Portion (Cam Curve Portion) S2 Second Cam Curve Portion (Cam Curve Portion)

Claims

1. Mounted on a crane, A winch brake device comprising a plurality of winches and a plurality of pedal units provided corresponding to each of the plurality of winches, Each of the pedal units A pedal, A brake valve that applies braking to the winch in conjunction with the operation of the pedal, A brake characteristic setting mechanism interposed between the pedal and the brake valve, Comprising, The brake characteristic setting mechanism Includes a cam plate that sets the relationship of the displacement amount of the stroke of the brake valve with respect to the operation of the pedal, A winch brake device characterized by this.

2. In the winch brake device according to Claim 1, Comprises a pedal lever that rotates in conjunction with the operation of the pedal, The cam plate is configured as a replaceable member that can be attached to and detached from the pedal lever, A winch brake device characterized by this.

3. In the winch brake device according to Claim 1, The cam plate is provided so that the rotation centers in the operation of the pedal coincide, and rotates integrally with the operation of the pedal, A winch brake device characterized by this.

4. In the winch brake device according to Claim 1, The cam plate has a plurality of cam curve portions at different positions in the circumferential direction, The plurality of cam curve portions are each set in the predetermined relationship, A winch brake device characterized by this.

5. In the winch brake device according to Claim 4, A pedal lever that rotates in conjunction with the operation of the pedal, Engaging means capable of changing the engagement position of the cam plate with respect to the pedal lever, The plurality of cam curve portions and the engagement position of the cam plate are pre-associated, A winch brake device characterized by this.

6. In the winch brake device according to Claim 5, The pedal lever has a shaft portion that rotatably supports the cam plate, The engaging means is composed of key grooves provided on each of the shaft portion and the cam plate, and a detachable key that connects between these key grooves, A winch brake device characterized by this.

7. In the winch brake device according to Claim 5 or 6, Each of the plurality of cam curve portions of the cam plate is provided with a mark indicating the engagement position with the pedal lever, A winch brake device characterized by this.

8. In the winch braking device according to claim 1, the cam plate has, as the relationship after the braking force output, a first region in which the relationship is set such that the displacement amount of the stroke with respect to the operation of the pedal becomes smaller as the operation of the pedal progresses, and a region after the first region, which is a second region in which the relationship is set such that the displacement amount of the stroke with respect to the operation of the pedal becomes larger than that in the first region as the operation of the pedal progresses. A winch braking device characterized by the above.

9. In the winch braking device according to claim 8, the cam plate has, as the relationship before the brake output, a third region in which the relationship is set such that the displacement amount of the stroke with respect to the operation of the pedal is larger than that in the first region and smaller than that in the second region as the operation of the pedal progresses. A winch braking device characterized by the above.

10. A crane equipped with the winch braking device according to any one of claims 1 to 6, 8, and 9.

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