JP2018043824A - Brake device of winch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operability of a negative-type brake device.SOLUTION: A brake device of a winch comprises: a first brake mechanism having a pressing member for making a plurality of friction plates pressure-contact with each other to generate a brake force, a first elastic member for pressing the pressing member toward the friction plates, and a first brake working fluid chamber for pressing the pressing member to a direction in which the pressing member is separated from the friction plates by being supplied with pressure oil, and lowering the brake force; and a second brake mechanism having an abutment part abutting on the pressing member, a second elastic member for pressing the pressing member toward the friction plates via the abutment part, and a second brake working fluid chamber for pressing the abutment part to a direction in which the abutment part is separated from the pressing member by being supplied with the pressure oil, and lowering the brake force.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a winch brake device.

  A winch brake device that brakes free fall rotation of a winch drum that is driven to rotate by a hydraulic motor is known (see Patent Documents 1 and 2). The brake device for a winch described in Patent Document 1 includes a brake cylinder having a positive side oil chamber that is pressurized in the braking action direction and a negative side oil chamber that is pressurized in the brake release direction.

  In Patent Document 1, an electromagnetic proportional pressure reducing valve is adopted as a brake valve connected to the positive side oil chamber, and the controller controls the brake valve in response to the output of the potentiometer being changed by operating a pedal or the like. It is described to do.

  Patent Document 2 discloses the pilot pressure in the negative side oil chamber in both cases of using a brake device as a service brake at the time of free fall and using a brake device as a parking brake (clutch) at the time of power hoisting. A negative brake device is disclosed in which the braking force is released by increasing the braking force and the braking force is generated by reducing the pilot pressure in the negative oil chamber.

JP 2000-16772 A Japanese Patent Laid-Open No. 2015-221702

  Patent Document 1 describes the adjustment of the pressure of the positive side oil chamber that is pressurized in the brake acting direction in order to improve the operability, but the negative side oil that is pressurized in the brake releasing direction. There is no mention of adjusting the chamber pressure.

  There is a demand for improvement in operability in a negative brake device that uses a brake device as a service brake when free-falling a suspended load.

  A winch brake device according to one aspect of the present invention is a negative brake device that generates a braking force based on a depression operation of a brake pedal, and a pressing member that presses a plurality of friction plates to generate a braking force; A first elastic member that presses the pressing member toward the friction plate, and a first brake operation that reduces the braking force by pressing the pressing member away from the friction plate when pressurized oil is supplied. A first brake mechanism having an oil chamber; a contact portion that contacts the pressing member; a second elastic member that presses the pressing member toward the friction plate via the contact portion; A second brake mechanism including a second brake hydraulic oil chamber that presses the contact portion in a direction away from the pressing member when pressure oil is supplied, and reduces the braking force. And said that you are.

  According to the present invention, operability can be improved in a negative brake device.

The external side view of the crane provided with the brake device. The hydraulic circuit diagram which shows the structure of the winch apparatus which has a brake device which concerns on the 1st Embodiment of this invention. The figure which shows the structure of a brake. (A) is the schematic diagram which looked at the rotational friction board from the axial direction, (b) is the EE sectional view schematic diagram of Fig.4 (a). (A) is a figure which shows the pressing force characteristic of a 1st piston, (b) is a figure which shows the pressing force characteristic of a 2nd piston, (c) is a figure which shows a brake pedal characteristic and a brake control valve characteristic, (d) is a figure. The figure which shows a braking force characteristic. The figure which shows the characteristic of the brake device which concerns on the modification of the 1st Embodiment of this invention. The hydraulic circuit diagram which shows the structure of the winch apparatus which has a brake device which concerns on the 2nd Embodiment of this invention. (A) is a figure which shows the pressing force characteristic of the 1st piston of the brake device which concerns on the 2nd Embodiment of this invention, (b) is the 2nd piston of the brake device which concerns on the 2nd Embodiment of this invention. The figure which shows the pressing force characteristic of this, (c) is a figure which shows the brake-pedal characteristic and brake-control-valve characteristic of the brake device based on the 2nd Embodiment of this invention, (d) is the 2nd Embodiment of this invention The figure which shows the control pressure characteristic of the 2nd piston of the brake device which concerns on a form, (e) is a figure which shows the braking force characteristic of the brake device which concerns on the 2nd Embodiment of this invention. The hydraulic circuit diagram which shows the structure of the winch apparatus which has a brake device which concerns on the 3rd Embodiment of this invention. (A) is a figure which shows the control pressure characteristic of the 2nd piston of the brake device which concerns on the 3rd Embodiment of this invention, (b) is the braking force characteristic of the brake device which concerns on the 3rd Embodiment of this invention. (C) is a figure which shows the control pressure characteristic of the 2nd piston of the brake device which concerns on the modification of the 3rd Embodiment of this invention, (d) is a figure of the 3rd Embodiment of this invention. The figure which shows the braking force characteristic of the brake device which concerns on a modification. The hydraulic circuit diagram which shows the structure of the winch apparatus which has a brake device which concerns on the 4th Embodiment of this invention. (A) is a figure which shows the pressing force characteristic of the 1st piston of the brake device which concerns on the 4th Embodiment of this invention, (b) is the 2nd piston of the brake device which concerns on the 4th Embodiment of this invention. The figure which shows the pressing force characteristic of this, (c) is a figure which shows the brake-pedal characteristic and brake-control-valve characteristic of the brake device which concern on the 4th Embodiment of this invention, (d) is the 4th Embodiment of this invention The figure which shows the braking force characteristic of the brake device which concerns on a form. (A) is a figure which shows the braking force characteristic of the brake device which concerns on the comparative example 1, (b) is a figure which shows the braking force characteristic of the brake device which concerns on the comparative example 2.

Hereinafter, an embodiment of a crane provided with a brake device according to the present invention will be described with reference to the drawings.
-First embodiment-
FIG. 1 is an external side view of a crane provided with a brake device. The crane 100 includes a traveling body 101, a revolving body 103 that is turnable on the traveling body 101, and a boom 104 that is pivotally supported by the revolving body 103. The revolving structure 103 is equipped with a hoisting winch 105 which is a winch for hoisting and a hoisting winch 106 which is a winch for raising and lowering a boom.

  A hoisting rope 105 a is wound around the hoisting winch 105, and the hoisting rope 105 a is wound or fed out by the rotation of the hoisting winch 105, and the hook 110 moves up and down. The hoisting rope 106 a is wound around the hoisting winch 106, and the hoisting rope 106 a is wound or fed out by the rotation of the hoisting winch 106, and the boom 104 is raised and lowered.

  FIG. 2 is a hydraulic circuit diagram showing the configuration of the winch device having the brake device according to the first embodiment of the present invention. In FIG. 2, the hydraulic circuit that drives the hoisting winch 105 is illustrated, and the hydraulic circuit that drives the hoisting winch 106 is not illustrated. The crane 100 includes a controller 18 that controls the operation 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.

  The controller 18 includes an arithmetic processing unit having a CPU and a storage device such as ROM and RAM, and other peripheral circuits, and controls the entire system of the crane 100.

  The winch device 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 device B. The main pump 12 supplies pressure oil to the hydraulic motor 1 and drives the hydraulic motor 1 to drive the winding drum 3 to wind up and down. 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 device B prevents free rotation of the winding drum 3 by braking the carrier shaft 4g of the planetary reduction mechanism 2.

  The brake device B includes a brake 4 mounted in the winding drum 3. The brake 4 is a wet multi-plate brake having a plurality of friction plates, and includes a first piston 4c and a second piston 4d that generate a braking force (braking force) by pressing the friction plates together.

  Hereinafter, for convenience of explanation, the rotation axis direction of the hoisting winch 105, that is, the central axis direction of the carrier shaft 4g is simply referred to as an axial direction. Further, the side on which the output shaft of the hydraulic motor 1 is disposed will be described as the front side of the winch device, and the opposite side in the axial direction will be described as the rear side of the winch device.

  The brake device B is a negative brake device (braking device), and includes a pressure contact force adjusting device that adjusts the pressure contact force between the friction plates. The pressure contact force adjusting device is supplied with pressure oil and a first spring 4e1 and a second spring 4e2 that apply a driving force to the first piston 4c and the second piston 4d so as to increase the pressure contact force between the friction plates. Thus, the first hydraulic cylinder device 4s1 and the second hydraulic cylinder device 4s2 are provided that apply a driving force to the first piston 4c and the second piston 4d so as to reduce the pressure contact force between the friction plates.

  In the present embodiment, the brake device B is a two-stage braking device including a first brake mechanism B1 and a second brake mechanism B2. In the brake device B, when the depression amount of the brake pedal 6a is small, the first brake mechanism B1 independently generates a braking force, and when the depression amount of the brake pedal 6a is large, the first brake mechanism B1 and the second brake mechanism B2 are used. Are configured to generate a braking force in cooperation with each other. Details of the structures of the first brake mechanism B1 and the second brake mechanism B2 will be described later.

  The brake device B also has a function as a clutch device that transmits and shuts off rotation between the hydraulic motor 1 and the winding drum 3. That is, the brake device B functions as a clutch and a parking brake at the time of power hoisting and stopping, and has a function as a service brake at the time of free fall. In this specification, the braking force required when the brake device B is used as a clutch is defined as “necessary clutch force”, and the braking force required when the brake device B is used as a service brake is “necessary braking force”. It is defined as

  The hydraulic circuit for driving the winch is switched by the controller 18 by the motor brake switching valve 7 that is controlled to be switched by the operation of the winch operating lever 13, the motor brake cylinder 8, the brake control valve 6 that is operated by the brake pedal 6a, and the controller 18. A brake switching valve 5 to be controlled and a cooling circuit safety valve 20 are provided. Further, in this hydraulic circuit, an operation pressure sensor 15 and a brake circuit pressure sensor 16 are provided to switch the operation mode of the brake 4 by switching the brake switching valve 5 and are connected to the controller 18, respectively. Further, a brake mode changeover switch 17 is connected to the controller 18. The operation mode of the brake 4 is switched to an automatic brake mode, which will be described later, or a neutral free mode.

  The planetary reduction mechanism 2 includes a sun gear 2a, a planetary gear 2b, and a ring gear 2c. The output shaft of the hydraulic motor 1 is connected to the sun gear 2 a of the planetary reduction mechanism 2. A planetary gear 2b is meshed with the sun gear 2a, and a ring gear 2c provided on the inner peripheral side of the take-up drum 3 is meshed with the planetary gear 2b. The planetary gear 2b is supported by a planetary carrier 2d. The carrier shaft 4g to which the planetary carrier 2d is fixed penetrates the side wall of the casing 4f of the brake 4 and reaches the brake 4. The carrier shaft 4g is supported by a bearing. A gap between the outer peripheral surface of the carrier shaft 4g and the through hole through which the carrier shaft 4g is inserted is sealed with an oil seal 4h.

  The casing 4f is a cylindrical housing member that houses a plurality of friction plates, pistons, springs, and the like. The casing 4f includes a first cylinder part 4f1 in which a plurality of friction plates are arranged on the inner side, a second cylinder part 4f2 in which the first piston 4c is arranged on the inner side, and a third cylinder in which the second piston 4d is arranged on the inner side. It has a cylinder part 4f3, a first end plate 4f4 that closes the opening end of the first cylinder part 4f1, and a second end plate 4f5 that closes the opening end of the third cylinder part 4f3. The first cylinder part 4f1, the second cylinder part 4f2, and the third cylinder part 4f3 are combined and integrated, and an accommodation space for accommodating each component of the brake 4 is formed inside the casing 4f.

  FIG. 3 is a diagram showing a configuration of the brake 4. FIG. 3 schematically shows a state where the friction plates are pressed against each other and a braking force is generated. In the housing space of the casing 4f, a first housing chamber 140a, a second housing chamber 140b, a carrier shaft chamber 141, a disk chamber 142, and an outer peripheral flow path 143 are formed.

  The first storage chamber 140a is a space in which the first piston 4c and the plurality of first springs 4e1 are stored. The second storage chamber 140b is a space in which the second piston 4d and the plurality of second springs 4e2 are stored. The carrier shaft chamber 141 is a space on the inner peripheral side of the disk chamber 142, and is a space in which the end of the carrier shaft 4g is accommodated. The disk chamber 142 is a space in which a plurality of annular friction plates (rotating friction plates 4a and fixed friction plates (mating plates) 4b) are accommodated. The outer peripheral flow path 143 is a space arranged on the outer peripheral side of the disk chamber 142.

  The carrier shaft chamber 141 is communicated with the outer peripheral flow path 143 via the disk chamber 142, and the outer peripheral flow path 143 is communicated with an inlet port 4j provided in the third cylindrical portion 4f3. The inlet port 4j provided in the third cylinder part 4f3 is communicated with the outer peripheral flow path 143 via a channel provided in the second cylinder part 4f2. The inlet port 4j is connected to the cooling oil pump 19 (see FIG. 2).

  The carrier shaft chamber 141 communicates with the spring chamber in the second storage chamber 140b through the opening of the first piston 4c and the opening of the second piston 4d. The spring chamber of the second storage chamber 140b communicates with an outlet port 4k provided in the second end plate 4f5. The outlet port 4k is connected to the tank 10 (see FIG. 2).

  The rotating friction plates 4 a and the fixed friction plates 4 b are alternately arranged in the axial direction in the disk chamber 142. A plurality of rotating friction plates 4a are engaged with the carrier shaft 4g so as to be movable in the axial direction by spline coupling, and the rotating friction plates 4a can rotate integrally with the carrier shaft 4g.

  A plurality of fixed friction plates 4b are engaged with the inner peripheral surface of the casing 4f so as to be movable in the axial direction by spline coupling. The fixed friction plates 4b are connected by a spring. For this reason, in the brake released state, the fixed friction plates 4b move so as to be separated from each other, and a gap is formed between the rotary friction plate 4a and the fixed friction plate 4b. A clearance is formed between the rotating friction plate 4a and the fixed friction plate 4b, so that drag torque during free fall (rotational resistance due to the viscosity of oil between the rotating friction plate 4a and the fixed friction plate 4b (so-called drag) Torque)) is reduced. In the present specification, the rotary friction plate 4a and the fixed friction plate 4b are also collectively referred to as a friction plate (brake disc).

  4A is a schematic view of the rotating friction plate 4a viewed from the axial direction, and FIG. 4B is a schematic cross-sectional view taken along the line EE of FIG. 4A. In the present embodiment, as shown in FIG. 4, annular friction material 148 having an outer diameter D1 and an inner diameter D2 is attached to both surfaces of the rotating friction plate 4a, and the friction material 148 of the rotating friction plate 4a When the fixed friction plate 4b is brought into pressure contact, a braking force (braking force) is generated by friction between the rotating friction plate 4a and the fixed friction plate 4b. The friction material 148 has a lattice-shaped groove 149 so that the cooling oil flows between the friction plates via the groove 149 even when the rotating friction plate 4 a and the fixed friction plate 4 b are in pressure contact with each other. become.

  As shown in FIG. 3, the first brake mechanism B1 and the second brake mechanism B2 are disposed between the end of the carrier shaft 4g and the second end plate 4f5 of the casing 4f. The first brake mechanism B1 has a first spring 4e1, a first piston 4c and a second cylinder part 4f2, and the second brake mechanism B2 has a second spring 4e2, a second piston 4d and a third cylinder part 4f3. doing.

  The first piston 4c includes a disk-shaped pressure plate 4c1 that is a pressing member that presses a plurality of friction plates to generate a braking force, a piston portion 4c2 that extends rearward from the outer peripheral portion of the pressure plate 4c1, have. The pressure plate 4c1 is disposed between the first spring 4e1 and the friction plate so as to separate the spring chamber of the first storage chamber 140a from the disk chamber 142.

  The pressure plate 4c1 includes a receiving portion 4q with which a contact portion 4d1 of a second piston 4d, which will be described later, is in contact, and a pressing portion 4r between the receiving portion 4q and the piston portion 4c2. A circular opening penetrating in the axial direction is provided in the central portion of the pressure plate 4c1, and an annular portion around the opening serves as a receiving portion 4q.

  The pressing portion 4r has a pressing surface 4r1 that comes into contact with the fixed friction plate 4b. The pressing surface 4r1 is an annular plane having an inner diameter that is the same as the inner diameter of the friction material 148 of the rotating friction plate 4a and an outer diameter that is the same as the outer diameter of the friction material 148 of the rotating friction plate 4a. D1 (D1> D2). A first spring 4e1 is disposed between a surface of the pressing portion 4r opposite to the pressing surface 4r1 and a receiving surface provided on the third cylindrical portion 4f3 of the casing 4f. The first spring 4e1 is an elastic member that presses (biases) the pressure plate 4c1 of the first piston 4c toward the friction plate in the axial direction by an elastic force, and has a linear characteristic.

  The piston portion 4c2 is a cylindrical member provided on the same axis as the carrier shaft 4g, and is disposed at a predetermined interval outward in the radial direction of the contact portion 4d1 of the second piston 4d. The piston portion 4c2 has one axial end portion (front end portion) coupled to the pressure plate 4c1, the central axial portion is the first sliding portion 4t1, and the other axial end portion (rear end portion) is the second sliding portion. Part 4t2. The outer diameter of the first sliding part 4t1 is smaller than the outer diameter of the second sliding part 4t2.

  The second cylindrical portion 4f2 includes a first support portion 4v1 that slidably supports the outer peripheral portion of the first sliding portion 4t1, and a second support portion that slidably supports the outer peripheral portion of the second sliding portion 4t2. 4v2. A piston seal is disposed between the first support part 4v1 and the first sliding part 4t1, and isolates a first brake hydraulic oil chamber 4m1 and an outer peripheral flow path 143 described later. A piston seal is disposed between the second support portion 4v2 and the second sliding portion 4t2, and isolates the first brake hydraulic fluid chamber 4m1 and the spring chamber of the first storage chamber 140a.

  The second piston 4d has a disk-like contact portion 4d1 that is in contact with the receiving portion 4q of the pressure plate 4c1 of the first piston 4c described above at the front end portion, and rearward from the outer peripheral portion of the contact portion 4d1. A cylindrical piston portion 4d2 extends toward the surface. An opening that penetrates in the axial direction is provided at the center of the contact portion 4d1. The opening and the spring chamber of the first storage chamber 140a are communicated with each other through a plurality of through holes penetrating in the radial direction.

  The second spring 4e2 is disposed between the surface of the contact portion 4d1 opposite to the surface that is in contact with the pressure plate 4c1 and the receiving surface provided on the second end plate 4f5. The second spring 4e2 is an elastic member that presses (biases) the second piston 4d toward the friction plate in the axial direction by an elastic force, and has a linear characteristic.

  The piston part 4d2 is a cylindrical member provided coaxially with the carrier shaft 4g and the piston part 4c2. The piston portion 4d2 has one axial end portion (front end portion) coupled to the contact portion 4d1, the central axial portion is the third sliding portion 4u3, and the other axial end portion (rear end portion) is the fourth slide. The moving part is 4u4. The outer diameter of the third sliding part 4u3 is smaller than the outer diameter of the fourth sliding part 4u4.

  The third cylindrical portion 4f3 includes a third support portion 4w3 that slidably supports the outer peripheral portion of the third sliding portion 4u3, and a fourth support portion that slidably supports the outer peripheral portion of the fourth sliding portion 4u4. 4w4. A piston seal is disposed between the third support portion 4w3 and the third sliding portion 4u3, and isolates a second brake hydraulic oil chamber 4m2 described later and a spring chamber of the first storage chamber 140a. A piston seal is disposed between the fourth support portion 4w4 and the fourth sliding portion 4u4 to isolate the second brake hydraulic oil chamber 4m2 from the spring chamber of the second storage chamber 140b.

  As described above, the piston portion 4c2 of the first piston 4c is disposed in the first storage chamber 140a so as to be slidable in the axial direction. In the first storage chamber 140a, a first brake hydraulic fluid chamber 4m1 is defined by the piston portion 4c2 and the second cylinder portion 4f2. The first brake hydraulic fluid chamber 4m1 includes an outer peripheral surface of the first sliding portion 4t1 of the piston portion 4c2, a front end surface of the second sliding portion 4t2 protruding outward from the outer peripheral surface, and a second support portion 4v2. This is a cylindrical oil chamber defined by an inner peripheral surface and a rear end surface of the first support portion 4v1 projecting inwardly from the inner peripheral surface.

  The first brake hydraulic oil chamber 4m1 communicates with a flow path 4n1 into which pressure oil for releasing the brake is introduced. The flow path 4n1 is formed in the second cylinder part 4f2 and the third cylinder part 4f3, and is connected to the first hydraulic oil introduction port 4p1 of the third cylinder part 4f3.

  As described above, the piston portion 4d2 of the second piston 4d is disposed in the second storage chamber 140b so as to be slidable in the axial direction. In the second storage chamber 140b, a second brake hydraulic fluid chamber 4m2 is defined by the piston portion 4d2 and the third cylinder portion 4f3. The second brake hydraulic oil chamber 4m2 includes an outer peripheral surface of the third sliding portion 4u3 of the piston portion 4d2, a front end surface of the fourth sliding portion 4u4 protruding outward from the outer peripheral surface, and a fourth support portion 4w4. This is a cylindrical oil chamber defined by the inner peripheral surface and the rear end surface of the third support portion 4w3 protruding inward from the inner peripheral surface.

  The second brake hydraulic oil chamber 4m2 communicates with a flow path 4n2 into which pressure oil for releasing the brake is introduced. The flow path 4n2 is formed in the third cylindrical portion 4f3 and the second end plate 4f5, and is connected to the second hydraulic oil introduction port 4p2 of the second end plate 4f5.

  The first hydraulic oil introduction port 4p1 and the second hydraulic oil introduction port 4p2 are connected to the pilot pump 9 via the brake control valve 6 and the brake switching valve 5 (see FIG. 2).

  The piston part 4c2 of the first piston 4c and the first brake hydraulic oil chamber 4m1 constitute a first hydraulic cylinder device 4s1. A driving force can be applied to the piston portion 4c2 by applying a pilot pressure to the first brake hydraulic fluid chamber 4m1.

  When the pressure in the first brake hydraulic oil chamber 4m1 decreases, for example, when the tank pressure is reached, the pressure plate 4c1 is pressed against the friction plate by the first spring 4e1, and the rotational friction plate 4a and the fixed friction plate 4b are pressed by the pressure plate 4c1. Is pressed. When the friction plates are pressed against each other, the frictional force generated on the surface of the rotating friction plate 4a (the surface of the friction material 148) acts on the carrier shaft 4g as a braking force, and the rotation of the carrier shaft 4g is prevented.

  When the pilot pressure oil from the pilot pump 9 is supplied to the first brake hydraulic oil chamber 4m1 and the pilot pressure acts on the piston portion 4c2 of the first piston 4c as the brake release pressure, the pressure plate 4c1 biases the first spring 4e1. Against this, it is pressed away from the friction plate and the braking force is reduced. When the pressure in the first brake hydraulic fluid chamber 4m1 becomes equal to or higher than the predetermined value P1, a gap is formed between the rotating friction plate 4a and the fixed friction plate 4b, and the pressure contact force between the rotating friction plate 4a and the fixed friction plate 4b is removed. Thus, the rotating friction plate 4a and the carrier shaft 4g can be rotated without receiving a braking force.

  The piston part 4d2 of the second piston 4d and the second brake hydraulic oil chamber 4m2 constitute a second hydraulic cylinder device 4s2. A driving force can be applied to the piston portion 4d2 by applying a pilot pressure to the second brake hydraulic fluid chamber 4m2.

  When the pressure in the second brake hydraulic oil chamber 4m2 decreases, for example, when the tank pressure is reached, the second spring 4e2 presses the pressure plate 4c1 toward the friction plate via the contact portion 4d1. Thus, the second brake mechanism B2 presses the rotating friction plate 4a and the fixed friction plate 4b in cooperation with the first brake mechanism B1. That is, the second brake mechanism B2 is configured to assist the first brake mechanism B1 and further increase the braking force.

  When the pilot pressure oil from the pilot pump 9 is supplied to the second brake hydraulic oil chamber 4m2, and the pilot pressure acts on the piston portion 4d2 of the second piston 4d as the brake release pressure, the contact portion 4d1 is attached to the second spring 4e2. The braking force is reduced by being pressed away from the pressure plate 4c1 against the force. When the pressure in the second brake hydraulic oil chamber 4m2 becomes equal to or higher than the predetermined value P2, a gap is formed between the contact portion 4d1 and the pressure plate 4c1, and the second brake mechanism B2 does not contribute to the braking force.

  The above-mentioned predetermined value P1 of pressure is the pressure in the first brake hydraulic fluid chamber 4m1 necessary for separating the pressure plate 4c1 of the first brake mechanism B1 from the friction plate, and the above-mentioned predetermined value P2 of pressure is 2 This is the pressure in the second brake hydraulic oil chamber 4m2 necessary for separating the contact portion 4d1 of the brake mechanism B2 from the pressure plate 4c1. The magnitude relationship between the predetermined value P1 and the predetermined value P2 is P1> P2.

  When the pressure acting on the first brake hydraulic fluid chamber 4m1 and the second brake hydraulic fluid chamber 4m2 is in the range of the predetermined value P2 or more and less than the predetermined value P1, the first brake mechanism B1 described above generates the braking force independently. When the pressure acting on the first brake hydraulic fluid chamber 4m1 and the second brake hydraulic fluid chamber 4m2 is less than the predetermined value P2, the first brake mechanism B1 and the second brake mechanism B2 described above cooperate to generate a braking force. .

  An operation in the automatic brake mode, which is a mode for performing power hoisting / lowering, and an operation in a neutral free mode, which is a mode for performing free fall, will be described. As shown in FIG. 2, in the automatic brake mode, the controller 18 switches the brake switching valve 5 to the position (D), and in the neutral free mode, the controller 18 switches the brake switching valve 5 to the position (C).

−Operation during power hoisting / lowering (automatic brake mode) −
When the winch operation lever 13 shown in FIG. 2 is operated to the winding position or the lowering position, the pilot pressure from the pilot pump 9 acts on the control valve 11 and the spool of the control valve 11 is driven. Thus, the hydraulic oil discharged from the main pump 12 is supplied to the hydraulic motor 1. At the same time, the pilot pressure from the pilot pump 9 also acts on the motor brake switching valve 7 via the high pressure selection valve 14. Accordingly, 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 driven to rotate.

  In the automatic brake mode, the brake switching valve 5 is switched to the position (D), and the pilot pressure from the pilot pump 9 that is the brake release pressure is shut off by the brake switching valve 5. The first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2 communicate with the tank 10, and the first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2 have a tank pressure. As a result, the rotating friction plate 4a and the fixed friction plate 4b are pressed against each other by the urging force of the first spring 4e1 and the second spring 4e2, and braking force is applied to the planetary carrier 2d. Fixed.

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

− Operation during free fall (neutral free mode) −
When the winch operation lever 13 is operated to the neutral position, the control valve 11 blocks the flow of pressure oil from the main pump 12 to the hydraulic motor 1. Since the pilot pressure oil is not supplied to the motor brake switching valve 7 via the high pressure selection valve 14, the motor brake switching valve 7 is switched to the position (B). Since the pilot pressure to the motor brake cylinder 8 is cut off by the motor brake switching valve 7, the motor brake is operated by the biasing force of the spring. In this state, when the braking force of the brake 4 is released, the take-up drum 3 freely rotates due to its own weight suspended from the hook 110.

  The brake device B includes a brake control valve 6 that reduces the pilot pressure from the pilot pump 9 in accordance with the operation amount of the brake pedal 6a and outputs the brake pressure as a brake release pressure, and controls the brake release pressure to increase the braking force. It has a function that can be adjusted. In the neutral free mode, the brake switching valve 5 is switched to the position (C), and the brake control valve 6 communicates with the first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2. For this reason, the brake release pressure generated by the brake control valve 6 acts on the first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2. The operator can adjust the brake force (braking force) by the brake 4 and adjust the free fall speed by adjusting the brake release pressure to the brake 4 via the brake control valve 6 by operating the brake pedal 6a.

  Switching to the neutral free mode is performed by operating the brake switching valve 5 according to a command from the controller 18 based on the determination values of the operation pressure sensor 15, the brake circuit pressure sensor 16, and the brake mode switching switch 17. . For example, the operation pressure detected by the operation pressure sensor 15 is smaller than a predetermined threshold (that is, the winch operation lever 13 is neutral), and the circuit pressure detected by the brake circuit pressure sensor 16 is a predetermined threshold. When it is detected that the brake mode changeover switch 17 has been switched to the operation position of the neutral free mode in a state smaller than that (ie, the brake pedal is depressed), the controller 18 switches from the automatic brake mode to the neutral free mode. Switch the operation mode to.

  In the hoisting winch 105, cooling oil (working oil) is forcibly circulated in order to cool the friction plate that generates heat during free fall braking. The cooling oil is supplied by a cooling oil pump 19 installed exclusively for the cooling oil.

  As described above, the casing 4 f is provided with the inlet port 4 j for introducing the cooling oil into the brake 4 and the outlet port 4 k for discharging the cooling oil to the outside of the brake 4. As shown in FIG. 3, the cooling oil introduced into the outer peripheral flow path 143 from the inlet port 4j flows into the disk chamber 142 from the outer peripheral side of the disk chamber 142, passes through the disk chamber 142, and passes through the inner periphery of the disk chamber 142. Flows into the carrier shaft chamber 141 on the side. The cooling oil introduced into the carrier shaft chamber 141 flows into the spring chamber of the second storage chamber 140b through the openings of the first piston 4c and the second piston 4d, and is discharged out of the casing 4f from the outlet port 4k. Return to 10.

  As the cooling oil passes between the plurality of friction plates arranged in the disk chamber 142, the heat generated in the friction plates is absorbed by the cooling oil, and the friction plates are cooled. As described above, since the groove 149 is provided in the friction material 148 of the rotating friction plate 4a, the cooling oil is passed through the groove 149 to the outer periphery even when the friction plates are in pressure contact with each other. It flows from the flow path 143 to the carrier shaft chamber 141.

  When the cooling oil passes through the disk chamber 142, a pressure difference due to passage resistance is generated and acts as an internal pressure on each chamber. The design pressure of the casing 4f is generally determined to be lower than the allowable pressure of the oil seal 4h. In the present embodiment, as shown in FIG. 2, a cooling circuit safety valve 20 is provided on the discharge side of the cooling oil pump 19 so that the internal pressure of the casing 4f is equal to or lower than the allowable pressure of the oil seal 4h. The cooling circuit safety valve 20 is a relief valve that discharges the cooling oil to the tank 10 when the discharge pressure of the cooling oil pump 19 reaches a set pressure, and regulates the maximum pressure of the hydraulic circuit.

  Various characteristics of the brake device according to the present embodiment will be described with reference to FIG. FIG. 5A is a diagram showing the pressing force characteristics of the first piston 4c, the horizontal axis indicates the pressure acting on the first brake hydraulic oil chamber 4m1, and the vertical axis indicates the pressure plate 4c1 of the first piston 4c. The pressing force applied to the friction plate is shown. FIG. 5 (b) is a diagram showing the pressing force characteristics of the second piston 4d, the horizontal axis indicates the pressure acting on the second brake hydraulic oil chamber 4m2, and the vertical axis indicates the first via the second piston 4d. The pressing force applied to the friction plate by the pressure plate 4c1 of the piston 4c is shown. As described above, the second piston 4d cooperates with the first piston 4c via the first piston 4c to apply a pressing force to the friction plate. In FIG. Only the pressing force contributed by 4d is shown.

  As shown in FIG. 2, with respect to the first piston 4c, the first piston 4c can be moved backward against the urging force of the first spring 4e1 by increasing the pressure in the first brake hydraulic oil chamber 4m1. it can. Similarly, for the second piston 4d, the second piston 4d can be moved rearward against the urging force of the second spring 4e2 by increasing the pressure in the second brake hydraulic fluid chamber 4m2.

  The two oil passages led from the first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2 merge outside the brake 4, and the merged oil passage is connected to the brake switching valve 5. That is, since the first brake hydraulic fluid chamber 4m1 and the second brake hydraulic fluid chamber 4m2 are in communication, the pilot pressure generated by the brake control valve 6 is the first brake hydraulic fluid chamber 4m1 and the second brake hydraulic fluid. It acts in the same way on the chamber 4m2.

  In the present embodiment, the pressure P2 necessary for separating the second piston 4d from the first piston 4c is half of the pressure P1 necessary for separating the first piston 4c from the friction plate. The pressure receiving areas of the first piston 4c and the second piston 4d are determined.

  On the vertical axis shown in FIGS. 5 (a) and 5 (b), the first piston when the first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2 are both at tank pressure (pressure = 0%). The respective pressing forces are shown with the sum of the pressing force by 4c and the pressing force by the second piston 4d being 100%. In the horizontal axis shown in FIGS. 5A and 5B, the pressure P1 at which the pressure plate 4c1 of the first piston 4c separates from the friction plate is defined as 100%, and the respective pressures are shown.

  As shown in FIG. 5A, the pressing force characteristic of the first piston 4c is linearly proportional to the pressure in the range where the pressure acting on the first brake hydraulic oil chamber 4m1 is 0% or more and 100% or less. The pressing force gradually decreases from 60% to 0%. As shown in FIG. 5B, the pressing force characteristic of the second piston 4d is linearly proportional to the pressure in the range where the pressure acting on the second brake hydraulic oil chamber 4m2 is 0% or more and less than 50%. The pressing force gradually decreases from 40% to 0%. The pressing force characteristic of the second piston 4d is set to 0% when the pressure acting on the second brake hydraulic fluid chamber 4m2 is in the range of 50% to 100%.

  As shown in the drawing, the pressing force of the second piston 4d is 0 when the pressure in the second brake hydraulic oil chamber 4m2 is in the range of 50% to 100%. That is, the second piston 4d is in contact with the first piston 4c and exerts a pressing force on the friction plate when the pressure in the second brake hydraulic oil chamber 4m2 is in the range of 0% to less than 50%, but it is 50% or more. Then, it is separated from the first piston 4c. That is, in the brake device B according to the present embodiment, the first piston 4c and the second piston are in the range where the pressures in the first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2 are 0% or more and less than 50%. 4d cooperates to apply a pressing force to the friction plate, and in the range of 50% to less than 100%, the first piston 4c is configured to apply the pressing force to the friction plate independently.

  The pressing force characteristic of the first piston 4c and the pressing force characteristic of the second piston 4d are obtained by changing the spring characteristics of the first spring 4e1 and the second spring 4e2 and the pressure receiving area of the first piston 4c and the second piston 4d. Can be adjusted.

  FIG. 5C shows the brake pedal characteristics and the brake control valve characteristics. The horizontal axis indicates the pedal stroke and the valve stroke. The pedal stroke indicates the ratio of the pedal stroke (depression amount), where 100% is a state where the brake pedal is fully depressed and 0% is a non-operation state where the brake pedal is not depressed. The valve stroke is 0% when the pump port P and the outlet port A are fully closed and the tank port T and the outlet port A are fully open, and the pump port P and the outlet port A are fully opened. A shows the ratio of the valve stroke (the amount of pushing the spool) of the brake control valve 6 with the fully closed pushing state being 100%.

  As shown in FIG. 5 (c), the brake pedal characteristic is that the pressure (the first brake hydraulic fluid chamber 4m1 and the second brake hydraulic fluid chamber is increased in accordance with the increase of the pedal stroke when the pedal stroke is in the range of 0% to 100%. 4m2 pressure) is gradually reduced in a linear proportion. The brake control valve characteristic is a characteristic in which the pressure gradually decreases in a linear proportion as the valve stroke decreases.

  FIG. 5D is a diagram illustrating the braking force characteristics, where the horizontal axis indicates the pedal stroke and the vertical axis indicates the braking force. In FIG. 5 (d), the ratio of the braking force is shown with the required clutch force as 100%. The required brake force is assumed to be 70% as an example (required brake force <required clutch force). As shown in FIG. 5D, the braking force characteristic of the brake device B of the present embodiment is a combination of the braking force characteristic T1 of the first brake mechanism B1 and the braking force characteristic T2 of the second brake mechanism B2. It has two-stage folding characteristics.

  As shown in FIG. 5 (d), only the braking force by the first brake mechanism B1 acts in the range of the pedal stroke 0% (pressure 100%) or more and less than 50% (pressure 50%) in the brake release state. As the pedal stroke increases, the braking force increases at the first rate of change a1. When the brake pedal 6a is further depressed, the pressing force of the second piston 4d is added to the pressing force of the first piston 4c. For this reason, the braking force by the first brake mechanism B1 and the second brake mechanism B2 acts in the range of 50% or more and 100% or less (pressure 0%) of the pedal stroke, and the second rate of change a2 according to the increase of the pedal stroke. The braking force increases at (a2> a1).

  In this way, the rate of change of braking force according to the amount of pedal depression is reduced in a region where the amount of pedal depression is small, and the rate of change of braking force according to the amount of pedal depression is increased in a region where the amount of pedal depression is large. Thus, good brake operability can be obtained.

According to the embodiment described above, the following operational effects can be obtained.
(1) The winch brake device B according to the present embodiment is a negative brake device that generates a braking force based on a depression operation of the brake pedal 6a, and includes a first brake mechanism B1 and a second brake mechanism B2. It has. The first brake mechanism B1 is supplied with pressure oil, a pressure plate 4c1 that presses a plurality of friction plates together to generate a braking force, a first spring 4e1 that presses the pressure plate 4c1 toward the friction plate, and pressure oil. The first brake hydraulic oil chamber 4m1 that presses the pressure plate 4c1 away from the friction plate to reduce the braking force. The second brake mechanism B2 is supplied with pressure oil, a contact portion 4d1 that contacts the pressure plate 4c1, a second spring 4e2 that presses the pressure plate 4c1 toward the friction plate via the contact portion 4d1. Thus, it has a second brake hydraulic oil chamber 4m2 that presses the contact portion 4d1 away from the pressure plate 4c1 and reduces the braking force.

  In the brake device B, when the depression amount of the brake pedal 6a is small, the first brake mechanism B1 independently generates a braking force, and when the depression amount of the brake pedal 6a is large, the first brake mechanism B1 and the second brake mechanism B2 are used. Are configured to generate a braking force in cooperation with each other. Thereby, operability can be improved in the negative brake device.

  FIG. 13A is a diagram illustrating a braking force characteristic of the brake device according to the first comparative example. Comparing the magnitude relationship between the required clutch force and the required brake force, generally, the required clutch force is often higher than the required brake force (required clutch force> required brake force). The reason for this is that the required clutch force is regulated by laws and regulations such as the crane construction standard, with the braking force in the outermost rope layer (5th to 6th layers) of the winding drum 3 being rated line pull × 1.5 or more. On the other hand, the required braking force can be sufficiently braked by assuming a dynamic load on the rope layer (2nd to 3rd layer) at the allowable weight (generally below the rated line pull) during excavation work. This is because the value is often set to a value below the required clutch force.

  For this reason, if the required clutch force is satisfied, the required brake force is also satisfied at the same time. However, as shown in FIG. 13 (a), when the pedal stroke is in the range of 0% or more and 100% or less, the characteristic in which the braking force increases linearly in proportion to the increase in the pedal stroke is excessively larger than necessary during free fall. A large braking force may be applied, and the operability may be deteriorated.

  Brake operation of the winch device is desired to have good controllability in a wide range from light load to heavy load. The braking force characteristic of the brake device of Comparative Example 1 is a characteristic in which the braking force is controlled in a straight line (linear) with respect to the entire stroke of the brake pedal from 0% to 100% (necessary clutch force). Excessive braking force will be generated during free fall. In particular, since the rate of change of the braking force (control gradient) with respect to the pedal stroke in the light load region is large, the operator feels that the controllability is poor due to the ON-OFF operation feeling. Also, in the heavy load region, the dynamic load increase due to gravitational acceleration and moment of inertia causes the operator to feel the illusion that the braking force is insufficient when the rate of change of the braking force (inclination of control) is small. There is a tendency to feel that it does not match.

  FIG. 13B is a diagram illustrating a braking force characteristic of the brake device according to the second comparative example. As shown in FIG. 13 (b), the pedal stroke is increased from 0% to 100% by the characteristic that the required brake force is discontinuously increased from the required brake force during the maximum depression operation (when the pedal stroke is 100%). In the range of less than%, the rate of change (slope) of the braking force with respect to the pedal stroke can be reduced as compared with the characteristics shown in FIG. However, since the change rate (gradient) is the same in the light load region and the heavy load region, there is room for improvement from the viewpoint of operability.

  In the present embodiment, as shown in FIG. 5D, the control slope (change rate) is reduced in the light load region, and the control slope (change rate) is increased in the heavy load region. Therefore, a good operational feeling can be obtained in the entire load region.

(2) The first brake hydraulic fluid chamber 4m1 and the second brake hydraulic fluid chamber 4m2 communicate with each other, and the second brake hydraulic fluid chamber necessary for separating the contact portion 4d1 of the second brake mechanism B2 from the pressure plate 4c1. The pressure P2 of 4m2 is smaller than the pressure P1 of the first brake hydraulic oil chamber 4m1 necessary for separating the pressure plate 4c1 of the first brake mechanism B1 from the friction plate (P2 <P1). Accordingly, the two-stage folding characteristic as shown in FIG. 5D can be obtained without requiring electrical control, and the operability can be improved.

-Modification of the first embodiment-
In the above-described embodiment, the example in which the braking force characteristic is a two-stage folding characteristic as illustrated in FIG. 5D has been described, but the present invention is not limited to this. FIG. 6 is a diagram illustrating characteristics of the brake device according to the modification of the first embodiment of the present invention. FIG. 6A is a diagram showing brake pedal characteristics and brake control valve characteristics, and FIG. 6B is a diagram showing braking force characteristics.

  In the present modification, as shown in FIG. 6A, when the pedal stroke is in the range of 0% or more and less than 100%, the pressure decreases in proportion from 100% to 30% as the pedal stroke increases. As the pedal stroke increases to 100%, the pressure decreases discontinuously from 30% to 0%. In FIG. 6 (a), for convenience of explanation, the pressure is shown as a characteristic that changes discontinuously from 30% to 0%. However, in practice, the pressure is not completely discontinuous.

  As shown in FIG. 6 (b), the braking force characteristic T1 of the first brake mechanism B1 indicates that the braking force ranges from 0% to 40% as the pedal stroke increases in the range of 0% to 100%. It is a characteristic that increases up to%. The braking force characteristic T2 of the second brake mechanism B2 is a characteristic in which the braking force increases from 0% to 30% as the pedal stroke increases in a range where the pedal stroke is 50% or more and 100% or less.

  In the braking force characteristic of the brake device B, only the braking force by the first brake mechanism B1 acts in the range of the pedal stroke in the brake released state from 0% (pressure 100%) to less than 50% (pressure 50%). In accordance with the increase in braking force, the braking force increases at the first rate of change b1. When the brake pedal 6a is further depressed, the pressing force of the second piston 4d is added to the pressing force of the first piston 4c. For this reason, the braking force by the first brake mechanism B1 and the second brake mechanism B2 acts in the range of 50% or more and 100% or less (pressure 0%) of the pedal stroke, and the second rate of change b2 according to the increase of the pedal stroke. The braking force increases at (b2> b1). As shown in FIG. 6 (a), when the pedal stroke is maintained at 100%, the pressure decreases to 0%. As shown in FIG. 6 (b), when the pedal stroke is maintained at 100%, the pressure decreases. Power also increases from 70% to 100%.

  According to such a modification, the rate of change (inclination) of the braking force with respect to the pedal stroke can be further reduced (b1 <a1, b2 <a2), and the pedal depression amount is in a wide range from 0% to 100%. Thus, the brake operation from the braking force of 0% to the necessary braking force can be performed. Further, the required clutch force can be generated by depressing the brake pedal 6a to the maximum. As a result, the operability can be further improved.

-Second Embodiment-
A brake device according to the second embodiment will be described with reference to FIGS. 7 and 8. In the figure, the same reference numerals are assigned to the same or corresponding parts as those in the first embodiment, and the differences will be mainly described. FIG. 7 is a hydraulic circuit diagram showing a configuration of a winch device having a brake device according to a second embodiment of the present invention.

  The second embodiment has the same configuration as the first embodiment, but the second hydraulic oil introduction port 4p2 that introduces pilot pressure oil into the second brake hydraulic oil chamber 4m2 of the second brake mechanism B2. Is different from the first embodiment in that an electromagnetic proportional valve 23 for connecting the pilot pump 9 and the tank 10 is provided.

  In the second embodiment, the first brake hydraulic oil chamber 4m1 is connected to the pilot pump 9 via the brake switching valve 5 and the brake control valve 6, whereas the second brake hydraulic oil chamber 4m2 is electromagnetically proportional. The pilot pump 9 is connected via a valve 23.

  The electromagnetic proportional valve 23 is controlled by a control signal (excitation current) output from the controller 18. That is, in the brake device B of the second embodiment, the controller 18 controls the electromagnetic proportional valve 23 to adjust the pilot pressure to the second brake hydraulic oil chamber 4m2 generated by the electromagnetic proportional valve 23, The braking force by the second brake mechanism B2 is adjusted.

  FIG. 8 (a) is a diagram showing the pressing force characteristics of the first piston, as in FIG. 5 (a). The horizontal axis indicates the pressure acting on the first brake hydraulic fluid chamber 4m1, and the vertical axis indicates the first. The pressing force applied to the friction plate by the pressure plate 4c1 of the piston 4c is shown. FIG. 8B is a diagram showing the pressing force characteristics of the second piston 4d, as in FIG. 5B, where the horizontal axis indicates the pressure acting on the second brake hydraulic oil chamber 4m2, and the vertical axis indicates the first The pressing force applied to the friction plate by the pressure plate 4c1 of the first piston 4c via the two pistons 4d is shown. In addition, like FIG.5 (b), only the pressing force which the 2nd piston 4d contributes is shown in FIG.8 (b).

  As shown in FIG. 8A, the pressing force characteristic of the first piston 4c is linearly proportional as the pressure increases in the range where the pressure acting on the first brake hydraulic fluid chamber 4m1 is 0% or more and 100% or less. The pressing force gradually decreases from 40% to 0%. As shown in FIG. 8B, the pressing force characteristic of the second piston 4d is linearly proportional to the pressure in the range where the pressure acting on the second brake hydraulic oil chamber 4m2 is 0% or more and less than 50%. The pressing force gradually decreases from 60% to 0%. The pressing force characteristic of the second piston 4d is set to 0% when the pressure acting on the second brake hydraulic fluid chamber 4m2 is in the range of 50% to 100%.

  FIG. 8C is a diagram showing the brake pedal characteristics and the brake control valve characteristics as in FIG. 5C. In the second embodiment, the characteristics are the same as those in the first embodiment. Yes.

  FIG. 8D is a diagram showing the control pressure characteristic of the second piston, the horizontal axis shows the brake control valve pressure, and the vertical axis shows the second piston control pressure. The brake control valve pressure refers to the pilot pressure output from the brake control valve 6 (that is, the pressure on the horizontal axis in FIG. 8A), and the second piston control pressure refers to the electromagnetic proportional valve. The pilot pressure (that is, corresponding to the pressure on the horizontal axis in FIG. 8B) output from 23.

  As shown in FIG. 8D, the second piston control pressure characteristic indicates that the second piston control pressure becomes 0 as the brake control valve pressure increases in the range where the brake control valve pressure is 0% or more and less than 80%. It is a characteristic that increases from 50% to 50%. The second piston control pressure characteristic is such that when the brake control valve pressure is in the range of 0% or more and less than 80%, the rate of change (increase rate) of the second piston control pressure gradually decreases as the brake control valve pressure increases. It is. In the second piston control pressure characteristic, the second piston control pressure is set to 50% when the brake control valve pressure is in the range of 80% to 100%.

  FIG. 8 (e) is a diagram showing the braking force characteristics as in FIG. 5 (d), in which the horizontal axis represents the pedal stroke and the vertical axis represents the braking force. As shown in FIG. 8 (e), only the braking force by the first brake mechanism B1 acts in the brake release state in the range of the pedal stroke from 0% (pressure 100%) to less than 20%, which increases the pedal stroke. Accordingly, the braking force increases at the first rate of change c1. When the brake pedal 6a is further depressed, the pressing force of the second piston 4d is added to the pressing force of the first piston 4c. Therefore, the braking force by the first brake mechanism B1 and the second brake mechanism B2 acts in the range of the pedal stroke of 20% or more and 100% or less, and the rate of change gradually increases as the pedal stroke increases, and the braking force Will increase.

  The storage device of the controller 18 stores in advance a second piston control pressure characteristic shown in FIG. 8D in a look-up table format. The controller 18 refers to the second piston control pressure characteristic table, and determines the second piston control pressure based on the brake control valve pressure detected by the brake circuit pressure sensor 16. The controller 18 outputs a control signal to the electromagnetic proportional valve 23 in order to generate the determined second piston control pressure by the electromagnetic proportional valve 23. Thereby, in this Embodiment, a brake device can be operated with the braking force characteristic shown in FIG.8 (e).

  In the second embodiment, an electromagnetic proportional valve 23 for generating a pilot pressure to the second brake hydraulic oil chamber 4m2 is provided, and the controller 18 is based on the pilot pressure generated by the brake control valve 6 to provide an electromagnetic proportional valve 23. The pilot pressure generated by the system is adjusted. For this reason, it becomes easy to adjust a braking force characteristic.

  For example, in the first embodiment, the braking force characteristic is a linear characteristic with two-stage folding, whereas in the second embodiment, the braking force characteristic is a characteristic that is continuous in a quadratic curve. It is said that. For this reason, in the transition period when the inclination of control changes, the operability without a sense of incongruity is obtained.

  In the first embodiment, the braking force characteristic is a two-stage folding characteristic, and if the light load area is excessively laid down, there is a concern that the inclination becomes too high in the medium load area. On the other hand, in the second embodiment, the maximum value of the pressing force by the first piston 4c is 40%, and the maximum value of the pressing force by the second piston 4d by setting the characteristics to be continuous with a quadratic curve. Is set to 60%, and the inclination of control in the light load region can be further lowered compared to the first embodiment (c1 <b1 <a1), and the operability in the light load region can be further improved. Furthermore, in the second embodiment, since the slope can be raised in a quadratic curve in the middle to the latter half of the pedal stroke, good control characteristics can be obtained even in the middle to heavy load region.

-Third embodiment-
With reference to FIG. 9 and FIG. 10, the brake device which concerns on 3rd Embodiment is demonstrated. In the figure, the same or corresponding parts as those in the second embodiment are denoted by the same reference numerals, and the differences will be mainly described. FIG. 9 is a hydraulic circuit diagram showing a configuration of a winch device having a brake device according to a third embodiment of the present invention.

  The third embodiment differs from the second embodiment in that the adjustment dial 24 installed in the cab can be adjusted to control characteristics of the electromagnetic proportional valve 23 in accordance with the operator's preference. is there. The adjustment dial 24 can set five levels from level 1 to level 5. The adjustment dial 24 outputs an operation signal indicating the set level to the controller 18. The controller 18 selects the second piston control pressure characteristic stored in the storage device based on the operation signal from the adjustment dial 24.

  FIG. 10A is a diagram showing the control pressure characteristic of the second piston of the brake device according to the third embodiment of the present invention, and the characteristic when the adjustment dial 24 is set to “level 3”. Is indicated by a thick line, and the characteristics when level 1, 2 and level 4, 5 are set are indicated by a thin line. The storage device stores five types of second piston control pressure characteristics in a look-up table format.

  The second piston control pressure characteristic when set to level 1 indicates that the second piston control pressure is from 0% to 50% as the brake control valve pressure increases in a range where the brake control valve pressure is not less than 0% and less than 20%. %, The second piston control pressure is 50% when the brake control valve pressure is in the range of 20% to 100%.

  The second piston control pressure characteristic when set to level 2 indicates that the second piston control pressure is 0% to 50% as the brake control valve pressure increases in the range where the brake control valve pressure is 0% or more and less than 40%. %, The second piston control pressure is 50% when the brake control valve pressure is in the range of 40% to 100%.

  The second piston control pressure characteristic when set to level 3 indicates that the second piston control pressure is from 0% to 50% as the brake control valve pressure increases in the range where the brake control valve pressure is 0% or more and less than 60%. %, The second piston control pressure is 50% in the range where the brake control valve pressure is 60% or more and 100% or less.

  The second piston control pressure characteristic when set to level 4 indicates that the second piston control pressure is 0% to 50% in accordance with the increase of the brake control valve pressure in the range where the brake control valve pressure is 0% or more and less than 80%. %, The second piston control pressure is 50% when the brake control valve pressure is in the range of 80% to 100%.

  When the level 5 is set, the second piston control pressure characteristic is such that the brake control valve pressure is in the range of 0% to 100%, and the second piston control pressure is increased from 0% to 50 as the brake control valve pressure increases. It is a characteristic that increases linearly up to%.

  Although not shown, the pressing force characteristic of the first piston, the pressing force characteristic of the second piston, the brake pedal characteristic, and the brake control valve characteristic are the same as those of the second embodiment (FIGS. 8A to 8 ( c)).

  Thus, since the characteristic of the second piston control pressure is set according to the operation of the adjustment dial 24, a braking force characteristic as shown in FIG. 10B is obtained.

  In general, two to three winch devices are mounted on one crane 100. For this reason, the load form of each winch apparatus may differ depending on the work contents. For example, in a clamshell operation, a winch device that supports a bucket and controls raising and lowering of the bucket and a winch device that controls opening and closing of the bucket are used.

  During excavation, in the operation of landing by free fall operation with the bucket open (released), the descent speed is adjusted with the heavy load bucket support winch device, and the bucket open / close winch device with light load Is an operation of closing the bucket by following the descending speed of the supporting winch device. Here, if the follow-up is delayed, the bucket is ground after the bucket is closed. On the other hand, if the follow-up is preceded, the wire rope of the winch device for opening and closing may be loosened and become a turbulent winding. For this reason, in the clamshell work, high operability is particularly required for the winch device for opening and closing the bucket.

  Thus, this embodiment (third embodiment) is effective when the load is different for each winch device and it is desired to specialize according to each load form. The adjustment of the braking force characteristic was rarely performed by the operator's self-judgment in the conventional braking device (band type brake), but depending on the method, the braking force itself may be adjusted to decrease, When a high braking force is required, the braking force may be insufficient.

  At present, when the wet brake built-in type has become mainstream, there is no one that can adjust the braking force characteristics, and there is a strong demand from users to cope with the various situations described above. According to this embodiment, the braking force characteristic can be easily adjusted in the driver's cab, and the required clutch force and the required braking force can be generated regardless of which characteristic is selected. There is no. Although an electric circuit is used for the control, since the negative control is adopted for the hydraulic control, the brake device can be operated to generate a braking force even when the power is lost due to a pipe rupture or the like. .

-Modification of the third embodiment-
In the above-described third embodiment, an example in which the second piston control pressure is increased in accordance with an increase in the brake control valve pressure in a linear proportional relationship within a predetermined brake control valve pressure range has been described. It is not limited to this. FIG.10 (c) is a figure which shows the control pressure characteristic of the 2nd piston of the brake device which concerns on the modification of the 3rd Embodiment of this invention, FIG.10 (d) is 3rd Embodiment of this invention. It is a figure which shows the braking force characteristic of the brake device which concerns on the modification of this form.

  In this modified example, as shown in FIG. 10 (c), the second piston control pressure is not linearly proportional to the increase in the brake control valve pressure, but the rate of change gradually decreases. It is a mode. Thereby, the braking force characteristic shown in FIG. 10 (d) can be obtained, and the operability can be improved.

-Fourth embodiment-
A brake device according to the fourth embodiment will be described with reference to FIGS. 11 and 12. In the figure, the same or corresponding parts as those in the second embodiment are denoted by the same reference numerals, and the differences will be mainly described. FIG. 11 is a hydraulic circuit diagram showing a configuration of a winch device having a brake device according to a fourth embodiment of the present invention.

  The fourth embodiment has the same configuration as that of the second embodiment, except that an electromagnetic switching valve 423 is provided instead of the electromagnetic proportional valve 23 (see FIG. 7). Different from the embodiment. In the fourth embodiment, the second brake hydraulic oil chamber 4m2 of the second brake mechanism B2 is connected to the pilot pump 9 via the electromagnetic switching valve 423. In other words, the electromagnetic switching valve 423 is provided between the pilot pump 9 and the second brake hydraulic oil chamber 4m2.

  The first brake hydraulic oil chamber 4m1 of the first brake mechanism B1 is connected to the brake control valve 6 via the brake switching valve 5. In other words, the brake switching valve 5 is provided between the brake control valve 6 and the first brake hydraulic oil chamber 4m1.

  The electromagnetic switching valve 423 is switched to the position (E) or the position (F). When the electromagnetic switching valve 423 is switched to the position (E), the pilot pump 9 and the second brake hydraulic oil chamber 4m2 are communicated. When the electromagnetic switching valve 423 is switched to the position (F), the flow of pilot pressure oil from the pilot pump 9 to the second brake hydraulic oil chamber 4m2 is interrupted, and the second brake hydraulic oil chamber 4m2 and the tank 10 are communicated. The

  The electromagnetic switching valve 423 is connected to the controller 418 and is controlled by the controller 418. The controller 418 operates the electromagnetic switching valve 423 and the brake switching valve 5 in synchronization. The controller 418 functionally includes a mode selection unit 418a, a first valve control unit 418b, and a second valve control unit 418c.

  When the neutral free mode is selected, the first valve control unit 418b outputs an ON signal (excitation current) to the brake switching valve 5, switches the brake switching valve 5 to the position (C), and 1 Brake hydraulic oil chamber 4m1 is connected.

  When the brake switching valve 5 is switched to the position (C), the pilot pressure generated by the brake control valve 6 acts on the first brake hydraulic oil chamber 4m1. In this state, the pressure of the pilot pressure oil supplied from the pilot pump 9 to the first brake hydraulic oil chamber 4m1 is adjusted by the brake control valve 6 based on the depression amount of the brake pedal 6a.

  When the neutral free mode is selected, the second valve control unit 418c outputs an ON signal (excitation current) to the electromagnetic switching valve 423, switches the electromagnetic switching valve 423 to the position (E), and the pilot pump 9 and the second The brake hydraulic fluid chamber 4m2 is communicated.

  When the electromagnetic switching valve 423 is switched to the position (E), the pressure oil discharged from the pilot pump 9 is supplied to the second brake hydraulic oil chamber 4m2, and the pressing force of the second piston 4d becomes zero.

  When the automatic brake mode is selected, the first valve control unit 418b outputs an off signal to the brake switching valve 5, switches the brake switching valve 5 to the position (D), the first brake hydraulic oil chamber 4m1 and the tank 10 To communicate.

  When the automatic brake mode is selected, the second valve control unit 418c outputs an off signal to the electromagnetic switching valve 423, switches the electromagnetic switching valve 423 to the position (F), the second brake hydraulic oil chamber 4m2, and the tank 10 To communicate.

  In the automatic brake mode, both the first brake hydraulic oil chamber 4m1 and the second brake hydraulic oil chamber 4m2 communicate with the tank 10, so that the pressing force of the first piston 4c and the pressing force of the second piston 4d are maximized. .

  Thus, in the brake device B according to the present embodiment, the first brake mechanism B1 independently generates a braking force in the neutral free mode, and the first brake mechanism B1 and the second brake mechanism B2 in the automatic brake mode. Are configured to generate a braking force in cooperation with each other.

Here, switching between the neutral free mode and the automatic brake mode by the controller 418 according to the present embodiment will be described in detail. The mode selection unit 418a selects either the neutral free mode or the automatic brake mode based on conditions described later.
When the automatic brake mode is set, when any of the following individual conditions 1 to 3 is satisfied, the mode selection unit 418a selects the neutral free mode. When the automatic brake mode is set, if any of the following individual conditions 1 to 3 is not satisfied, the mode selection unit 418a maintains the automatic brake mode.
(Individual condition 1) The winch operation lever 13 is neutral (individual condition 2) The brake pedal 6a is depressed (individual condition 3) The brake mode changeover switch 17 is operated to the operation position in the neutral free mode. about

  Whether or not the winch operation lever 13 is neutral is determined by the mode selection unit 418a as follows. When the operation pressure Pp detected by the operation pressure sensor 15 is less than a predetermined threshold value Pp0, the mode selection unit 418a determines that the winch operation lever 13 is neutral, and the operation pressure Pp is equal to or greater than the threshold value Pp0. In this case, it is determined that the winch operation lever 13 is not neutral. The threshold value Pp0 is a threshold value for determining whether or not the winch operation lever 13 is neutral, and is stored in the storage device of the controller 418 in advance.

  Whether or not the brake pedal 6a is depressed is determined by the mode selection unit 418a as follows. When the circuit pressure Pb detected by the brake circuit pressure sensor 16 is less than a predetermined threshold value Pb0, the mode selection unit 418a determines that the brake pedal 6a is depressed, and the circuit pressure Pb is greater than or equal to the threshold value Pb0. If there is, it is determined that the brake pedal 6a is not depressed. The threshold value Pb0 is a threshold value for determining whether or not the brake pedal 6a is depressed, and is stored in advance in the storage device of the controller 418.

  When the automatic brake mode is switched to the neutral free mode, the brake switching valve 5 is switched to the position (C), so that the free fall is caused by supplying the hydraulic pressure of the brake control valve 6 to the first brake hydraulic oil chamber 4m1. It becomes possible.

  When the neutral free mode is selected and the individual condition 1 or the individual condition 3 described above is not satisfied, for example, when the winch operation lever 13 is operated to the winding side, the mode selection unit 418a automatically Select the brake mode. When the neutral free mode is selected, if both the individual condition 1 and the individual condition 3 described above are satisfied, the mode selection unit 418a maintains the neutral free mode.

  For this reason, if the winch operation lever 13 is operated to the winding side when the neutral free mode is set, the mode is switched to the automatic brake mode. When the winch operation lever 13 is returned to neutral from this state, the neutral free mode is restored. Therefore, the operator can continuously perform a series of operations from the free fall work to the power hoisting work or from the power hoisting work to the free fall work.

  FIG. 12 (a) is a diagram showing the pressing force characteristics of the first piston, as in FIG. 8 (a). The horizontal axis indicates the pressure acting on the first brake hydraulic fluid chamber 4m1, and the vertical axis indicates the first. The pressing force applied to the friction plate by the pressure plate 4c1 of the piston 4c is shown. FIG. 12B is a diagram showing the pressing force characteristics of the second piston 4d, as in FIG. 8B, in which the horizontal axis indicates the pressure acting on the second brake hydraulic oil chamber 4m2, and the vertical axis indicates the first The pressing force applied to the friction plate by the pressure plate 4c1 of the first piston 4c via the two pistons 4d is shown. In addition, like FIG.8 (b), in FIG.12 (b), only the pressing force which the 2nd piston 4d contributes is shown.

  As shown in FIG. 12 (a), the pressing force characteristic of the first piston 4c is linearly proportional as the pressure increases in the range where the pressure acting on the first brake hydraulic oil chamber 4m1 is 0% to 100%. The pressing force gradually decreases from 70% to 0%. As shown in FIG. 12B, the pressing force characteristic of the second piston 4d is linearly proportional as the pressure increases in the range where the pressure acting on the second brake hydraulic oil chamber 4m2 is 0% or more and less than 50%. The pressing force gradually decreases from 30% to 0%. The pressing force characteristic of the second piston 4d is set to 0% when the pressure acting on the second brake hydraulic fluid chamber 4m2 is in the range of 50% to 100%.

  FIG. 12C is a diagram showing the brake pedal characteristics and the brake control valve characteristics, as in FIG. 8C. In the fourth embodiment, the characteristics are the same as those in the second embodiment. Yes.

  FIG.12 (d) is a figure which shows a braking force characteristic similarly to FIG.8 (e), the pedal stroke is shown on the horizontal axis and the braking force is shown on the vertical axis | shaft. As shown in FIG. 12 (d), when the neutral free mode is selected, the pedal stroke in the brake release state is 0% (the pressure of the first brake hydraulic oil chamber 4m1 is 100%) or more and 100% (the first brake operation). Since only the braking force by the first brake mechanism B1 acts in the range below the pressure 0% of the oil chamber 4m1, the braking force increases linearly in proportion to the increase of the pedal stroke. When the automatic brake mode is selected, regardless of the depression amount of the brake pedal 6a, the pressing force of the second piston 4d and the pressing force of the first piston 4c are maximized, and the first brake mechanism B1 and the second brake mechanism B2 The required clutch force can be obtained by the braking force of.

  In the first to third embodiments, when the neutral free mode is selected, the braking force can be increased to the required clutch force when the pedal stroke is 100%. However, since the necessary clutch force has a sufficient surplus as a value determined by laws and regulations, it is necessary and sufficient in the free fall work if the braking force can be increased to the necessary brake force.

  According to the fourth embodiment, when the automatic brake mode is set, the first brake mechanism B1 and the second brake mechanism B2 cooperate to generate the necessary clutch force, and when the neutral free mode is set. The first braking mechanism B1 can independently adjust the braking force to the required braking force. That is, according to the present embodiment, the necessary braking force can be appropriately switched according to the mode. In the neutral free mode, since the rate of change (inclination) of the braking force with respect to the pedal stroke can be reduced compared to Comparative Example 1 (see FIG. 13A), the operability is improved compared to Comparative Example 1. Yes.

The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.
(Modification 1)
In the above-described embodiment, the brake device B including the two brake mechanisms of the first brake mechanism B1 and the second brake mechanism B2 has been described as an example, but the present invention is not limited to this. Three or more brake mechanisms may be provided. For example, a third brake mechanism may be provided in addition to the first brake mechanism B1 and the second brake mechanism B2. In this case, the third brake mechanism resists the contact member that contacts the contact portion 4d1 of the second brake mechanism B2, the elastic member that presses the member toward the contact portion 4d1, and the elastic force of the elastic member. This can be realized by including a hydraulic cylinder device that presses the contact member away from the contact portion 4d1.

(Modification 2)
In the above-described embodiment, the brake device applied to the winch device of the crane has been described as an example, but the present invention is not limited to this. The present invention can be applied to a brake device applied to a winch device mounted on various work machines.

  Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other embodiments conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

4a Rotating friction plate (friction plate), 4b fixed friction plate (friction plate), 4c first piston, 4c1 pressure plate (pressing member), 4c2 piston portion, 4d second piston, 4d1 contact portion, 4d2 piston portion, 4e1 First spring (first elastic member), 4e2 Second spring (second elastic member), 4m1 first brake hydraulic oil chamber, 4m2 second brake hydraulic oil chamber, 4s1 first hydraulic cylinder device, 4s2 second hydraulic cylinder device 5, brake switching valve (first switching valve), 6 brake control valve, 6a brake pedal, 9 pilot pump (hydraulic power source), 10 tank, 13 winch operation lever (winch operation member), 16 brake circuit pressure sensor, 17 brake Mode change switch (mode change operation member), 18 controller (control device), 23 electromagnetic proportional valve 24 adjusting dial (adjustment member), B brake device, B1 the first brake mechanism, B2 the second brake mechanism, 100 cranes, 101 traveling body, 103 swing structure 423 solenoid switching valve (second switching valve)

Claims (7)

In a negative brake device that generates a braking force based on the depression of the brake pedal,
A pressing member that presses a plurality of friction plates together to generate a braking force, a first elastic member that presses the pressing member toward the friction plate, and pressure oil is supplied to cause the friction of the pressing member. A first brake mechanism that has a first brake hydraulic fluid chamber that presses away from the plate and reduces the braking force;
A contact portion that is in contact with the pressing member, a second elastic member that presses the pressing member toward the friction plate via the contact portion, and the contact portion by being supplied with pressure oil A winch brake device, comprising: a second brake mechanism having a second brake hydraulic fluid chamber that presses in a direction away from the pressing member to reduce the braking force. The winch braking device according to claim 1,
When the amount of depression of the brake pedal is small, the first brake mechanism generates a braking force alone, and when the amount of depression of the brake pedal is large, the first brake mechanism and the second brake mechanism cooperate. A winch brake device characterized by being configured to generate a braking force. The winch braking device according to claim 2,
The first brake hydraulic fluid chamber and the second brake hydraulic fluid chamber communicate with each other;
The pressure in the second brake hydraulic fluid chamber necessary to separate the contact portion of the second brake mechanism from the pressing member is necessary to separate the pressing member of the first brake mechanism from the friction plate. The winch brake device, wherein the pressure is lower than the pressure in the first brake hydraulic fluid chamber. The winch braking device according to claim 2,
A brake control valve that is operated by the brake pedal and generates a pilot pressure to the first brake hydraulic oil chamber;
An electromagnetic proportional valve for generating a pilot pressure to the second brake hydraulic fluid chamber;
And a control device that adjusts a pilot pressure generated by the electromagnetic proportional valve based on a pilot pressure generated by the brake control valve. The brake device for a winch according to claim 4,
An adjustment member provided in the cab,
The control device determines a characteristic of a pilot pressure generated by the electromagnetic proportional valve based on a signal from the adjustment member, and the winch brake device. The winch braking device according to claim 1,
A brake control valve that adjusts the pressure of pressure oil supplied from a hydraulic pressure source to the first brake hydraulic oil chamber based on the depression amount of the brake pedal;
A first switching valve provided between the brake control valve and the first brake hydraulic oil chamber;
A second switching valve provided between a hydraulic pressure source and the second brake hydraulic oil chamber,
A mode selection section for selecting either the neutral free mode or the automatic brake mode;
When the neutral free mode is selected, the first switching valve is controlled so that the brake control valve communicates with the first brake hydraulic fluid chamber, and when the automatic brake mode is selected, the first brake A first valve control unit that controls the first switching valve so as to communicate the hydraulic oil chamber and the tank;
When the neutral free mode is selected, the second switching valve is controlled so that a hydraulic pressure source communicates with the second brake hydraulic fluid chamber. When the automatic brake mode is selected, the second brake hydraulic fluid is selected. A winch brake device, further comprising: a control device having a second valve control unit that controls the second switching valve so as to communicate the chamber and the tank. The winch braking device according to claim 6,
The mode selection unit selects the neutral free mode when the mode switching operation member is operated to the neutral free mode, the winch operation member for operating the winch is neutral, and the brake pedal is depressed. The winch brake device, wherein the automatic brake mode is selected when the winch operating member is operated when the neutral free mode is selected.

Images