Hydraulic breaker valve adjuster

Abstract

To provide a hydraulic breaker valve adjuster which can easily set an operation pressure of a hydraulic breaker at a specification pressure.SOLUTION: A valve adjuster 40 includes: a sleeve 50 interposed in a discharge passage 128 connected to a low pressure circuit 127 on a breaker body 10 side; and an adjuster 60 internally fitted to the sleeve 50 so as to adjust an engaging position in an axial direction. The sleeve is mounted so that a throttle part 61 at a tip of the sleeve 50 is positioned in the discharge passage 128, and the throttle part 61 is arranged at the position for opening / closing a throttle flow passage part 51 of a plug 150. By adjusting the engaging position of the adjuster 60 in the axial direction, an opening amount of the throttle flow passage part 51 is changed. The throttle flow passage part 51 is provided by a plurality of stages of flow passages being separated in the axial direction, and according to the engaging position of the adjuster 60, the plurality of stages of throttle flow passage parts 51 provided at the sleeve 50 is communicated sequentially and a passing flow rate to the low pressure circuit 127 is changed stepwise.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a hydraulic breaker, and more particularly to a valve adjuster for adjusting the amount of hydraulic oil in this type of hydraulic breaker on the breaker body side. [Background technology]

[0002] Hydraulic breakers are used by being attached to the arms of work machines such as hydraulic excavators (see, for example, Patent Document 1). The amount of oil discharged, which is the power supplied from the hydraulic excavator to the hydraulic breaker, depends on the characteristics of the hydraulic excavator's pump (i.e., pump capacity, pump efficiency, and oil volume setting). Therefore, to fully utilize the performance of the hydraulic breaker, it is necessary to always maintain the operating pressure of the hydraulic breaker at the specified value.

[0003] Therefore, in hydraulic breakers, a throttle is provided on the low-pressure circuit side. For example, this type of arrangement is such that the piston rear chamber and the low-pressure circuit are connected via a valve, and the passage is throttled at the intersection of the low-pressure circuit and a discharge passage, which is a communication passage connecting this valve to the low-pressure circuit, to limit the flow rate of pressurized oil passing through to the low-pressure circuit side, thereby ensuring the desired operating pressure. In the case of a variable throttle, a cartridge-type throttle called a valve adjuster is placed in the discharge passage of the valve on the breaker body side as described above, and the flow rate to the low-pressure circuit is adjusted by changing the opening area of ​​the discharge passage.In the case of a fixed throttle, the flow rate to the low-pressure circuit is adjusted each time by a throttle with a different diameter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 5-146976 (Fig. 1) Summary of the Invention [Problem to be solved by the invention]

[0005] Here, as shown in FIG. 10(a), a conventional valve adjuster has a plug 150 and an adjuster 160 fitted inside the plug 150, with the tip of the adjuster 160 protruding into the discharge passage 128 and forming a variable throttle for the pressurized oil from the rear chamber of the piston that flows into the low-pressure circuit 127. Conventional valve adjusters adjust the axial engagement position of adjuster 160 relative to plug 150 (the arrow in the figure shows an image of adjusting the axial engagement position). As a result, as shown in Figure 1(b), an opening adjustment structure is created in which the amount of flow passing through the low-pressure circuit changes proportionally to the adjuster opening depending on the degree to which the tip of adjuster 160 protrudes into discharge passage 128.

[0006] However, in the case of a structure in which the flow rate to the low-pressure circuit changes proportionally depending on the degree to which the adjuster protrudes into the discharge passage according to the screw-in position, there is variation depending on the number of turns of the adjuster, and it is difficult to reliably set the desired flow rate by adjusting the degree to which the adjuster protrudes into the discharge passage as a variable throttle, which causes a problem of affecting the stability of the operating pressure.Furthermore, in the case of a fixed throttle, it is necessary to have multiple types of throttles, which causes a problem of being troublesome when dealing with rental machines that are installed on various excavators.

[0007] Furthermore, some customers who use hydraulic breakers do not only operate them at the standard oil discharge rate, but also operate them with the oil discharge rate set to the minimum in order to prioritize fuel efficiency, or conversely, operate them with the oil discharge rate set to a large amount in order to prioritize rapid construction. Therefore, even for hydraulic excavators of the same class, there is a demand for the operating pressure to be easily set to the specified pressure for roughly three oil volume options: small, standard, and large.In addition, even when setting up a hydraulic breaker on a leased machine, there is a demand for it to be easy to set to the specified pressure.

[0008] The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a valve adjuster that can easily set the operating pressure of a hydraulic breaker to a specified pressure. [Means for solving the problem]

[0009] In order to solve the above problems, one aspect of the present invention provides a valve adjuster for a hydraulic breaker that is attached to a breaker body to adjust the amount of pressurized oil supplied from outside, and includes a cylindrical sleeve that is interposed in a communicating passage that connects to a low-pressure circuit on the breaker body side, and an adjuster that is screwed onto the sleeve so that its axial engagement position can be adjusted. The sleeve has multiple-stage throttle passages at its tip that are spaced apart in the axial direction and have non-communicating sections formed between the throttle passages, and is attached to the breaker body so that the multiple-stage throttle passages are located within the communicating passage. The adjuster is configured so that the throttle section at its tip sequentially connects the flow paths of the multiple-stage throttle passages in order to communicate with each other, depending on the screw engagement position, thereby gradually changing the flow rate passing through to the low-pressure circuit. [Effects of the Invention]

[0010] According to the present invention, the flow rate to the low-pressure circuit can be changed in stages by sequentially connecting the multiple throttle passages provided in the sleeve depending on the screw position of the adjuster, so that the operating pressure of the hydraulic breaker can be easily set to the specified pressure. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic vertical cross-sectional view showing an example of the configuration of a breaker body in an embodiment of a hydraulic breaker according to an aspect of the present invention, in which the piston is in the retraction stroke state. FIG. [Figure 2] FIG. 2 is an exploded enlarged view of the valve adjuster portion in FIG. 1. [Figure 3] FIG. 2 is a perspective view of a sleeve that constitutes the valve adjuster of the embodiment. [Figure 4] FIG. 2 is a perspective view of an adjuster constituting the valve adjuster of the embodiment. [Figure 5] 1 is a diagram illustrating an adjustment state by a valve adjuster according to an embodiment, and shows the adjuster in a fully closed state. FIG. [Figure 6] 10 is a diagram illustrating an adjustment state by the valve adjuster of the embodiment, and shows a state in which the opening amount of the sleeve is in the first stage. FIG. [Figure 7] 10 is a diagram illustrating an adjustment state by the valve adjuster of the embodiment, showing the state in which the opening amount of the sleeve is in the second stage. FIG. [Figure 8] FIG. 10 is a diagram illustrating an adjustment state by the valve adjuster of the embodiment, showing the third stage of the sleeve opening amount (fully open state). [Figure 9] 10 is a graph showing the relationship between the opening degree of the adjuster and the flow rate of the air passing through the adjuster according to the embodiment. [Figure 10] 1A and 1B are diagrams illustrating a conventional valve adjuster, where FIG. 1A is a schematic longitudinal cross-sectional view showing the opening adjustment portion of the conventional valve adjuster, and FIG. 1B is a graph showing the relationship between the opening of the conventional adjuster and the flow rate. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are schematic. Therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc. differ from the actual ones, and the drawings also include portions where the relationship and ratio of dimensions differ from each other. Furthermore, the embodiments described below are intended to exemplify devices and methods for embodying the technical ideas of the present invention, and the technical ideas of the present invention do not limit the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0013] [Hydraulic breaker] First, a hydraulic breaker (breaker body) to which the valve adjuster of this embodiment is attached will be described. The hydraulic breaker of this embodiment is used by being attached to the arm of a work machine such as a hydraulic excavator, and the breaker body 10 shown in FIG. 1 is attached to the arm of the work machine via a bracket (not shown).

[0014] As shown in the figure, the breaker body 10 includes a cylindrical piston 15 and a cylinder 11 into which the piston 15 slides. The piston 15 slides in the cylinder 11 by means of a cylinder liner 16 at the front of the cylinder 11 and a seal retainer 17 at the rear of the cylinder 11, allowing the piston 15 to move forward and backward in the axial direction. A front piston front chamber 11a and a rear piston rear chamber 11b are defined between the cylinder 11 and the piston 15 by a predetermined stepped shape or the like. A back head 13, which defines a gas chamber therein, is attached to the rear end of the cylinder 11.

[0015] A front head 12 is coaxially attached to the front of the cylinder 11, and a chisel 14 is supported on the front head 12 coaxially with a piston 15. The front head 12, cylinder 11, and back head 13 are integrally connected by a through bolt 20 inserted from the rear end of the back head 13.

[0016] An accumulator 21 and a valve housing 101 are provided on the same side of the cylinder 11. A valve chamber space 105 is formed inside the valve housing 101, and a control valve 30 accommodating a valve 106 is provided in the valve chamber space 105. The valve chamber space 105 is constantly connected to high pressure via a high-pressure circuit 124 on the pump P side, and necessary control passages are connected to the side of the valve chamber space 105 in appropriate positions so as to communicate with the valve chamber space 105.

[0017] In the control valve 30, the valve 106 moves back and forth in the axial direction depending on the difference in pressure-receiving area between the front and rear axial directions to switch the control passage, so that when the piston rear chamber 11b is connected to the low-pressure circuit 127 on the tank T side, the piston 15 moves back, and when the piston rear chamber 11b is connected to the high-pressure circuit 124, the piston 15 moves forward. Note that the operating mechanisms of the impact device and individual components in the hydraulic breaker 10 of this embodiment are basically known, so a detailed description will be omitted.

[0018] [Valve adjuster] The valve adjuster 40 of this embodiment will be described in detail below. In the hydraulic breaker described above, in order to adjust the amount of pressurized oil supplied from the body of the work machine, as shown in FIG. 1, a discharge passage 128 of the valve 106 is provided in the valve housing 101 on the breaker body 10 side as a communication passage connecting to a low-pressure circuit 127, and a valve adjuster 40 is fitted in a mounting hole 101d formed to communicate with this discharge passage 128.

[0019] As shown in FIG. 2, the valve adjuster 40 of this embodiment includes a cylindrical sleeve 50 having a throttle flow path portion 51 interposed in the low-pressure circuit 127 of the breaker body 10, an adjuster 60 mounted inside the sleeve 50 so that the threaded position in the axial direction can be adjusted, and a nut 70 for preventing loosening. The valve adjuster 40 of this embodiment is disposed, for example, in a mounting hole 101d that is provided in the valve housing 101 so as to communicate with the intersection of the discharge passage 128 of the valve 106 and the low-pressure circuit 127, which are connected from the piston rear chamber 11b, and is disposed in a location that is suitable for ensuring the reliability of the oil volume characteristics. Note that in this specification, the side of the valve adjuster 40 in the axial direction that is on the side of the discharge passage 128 that is connected to the low-pressure circuit 127 is referred to as the "tip side," and the side opposite the side on the side of the discharge passage 128 is referred to as the "base side."

[0020] More specifically, as shown in the figure, the sleeve 50 is a hollow cylindrical member having, in order from the tip, a throttled flow path portion 51, a male thread portion 52, an O-ring mounting groove 53, and a nut portion 54. Inside the hollow cylinder, a spigot female portion 55 is formed at the tip side, penetrating in the axial direction and coaxially with the outer diameter of the throttled flow path portion 51, and a female thread 56 is provided inside the nut portion 54. Note that an O-ring is not shown in the figure.

[0021] As shown in the perspective view of Fig. 3, the throttle passage section 51 of the sleeve 50 is provided with multiple stages of throttle passages 51a-c spaced apart in the axial direction. Note that the thread shape is not shown in Fig. 3. As shown in Fig. 5, the sleeve 50 is mounted in the mounting hole 101d of the valve housing 101 so that the multiple stages of throttle passages 51a-c are positioned within the discharge passage 128.

[0022] In this embodiment, the throttled flow path section 51 at the tip of the sleeve 50 has multiple stages (three stages in this embodiment) of flow paths 51a, 51b, 51c provided at the tip of the sleeve 50. Each stage 51a, 51b, 51c of the throttled flow paths 51a to 51c is formed by a set of multiple semicircular arc grooves or through holes that are spaced apart in the circumferential direction and communicate in the radial direction at positions on the same circumference of each stage 51a, 51b, 51c.

[0023] That is, of the multiple stages of throttle flow paths 51a-c, the first stage flow path 51a at the tip is composed of a set of multiple semicircular arc grooves formed at a first concentric position on the tip surface of the throttle flow path section 51, and the multiple semicircular arc grooves are spaced apart circumferentially and formed radially along the radial direction, forming a crown shape. In this embodiment, the first stage flow path 51a has eight semicircular grooves spaced apart in the circumferential direction and extending radially in the radial direction, forming communication holes, and the angle between the centers of adjacent semicircular grooves in the circumferential direction is 45°.

[0024] Furthermore, among the multiple stages of throttle flow paths 51a-c, the middle second stage flow path 51b is provided at a second circumferential position spaced further axially toward the base end than the first stage flow path 51a, and is configured by a group of multiple small-diameter communicating holes spaced apart radially in the circumferential direction. In this embodiment, the second stage flow path 51b is formed by eight through holes that are spaced apart circumferentially and radially penetrate the first stage flow path 51a at positions that are circumferentially offset by 22.5° from the centers of the semicircular arc grooves of the first stage flow path 51a. Therefore, the angle between the centers of adjacent through holes in the circumferential direction is 45°.

[0025] Furthermore, among the multiple-stage throttle flow paths 51a to c, the third stage flow path 51c on the base end side is provided at a third circumferential position spaced further axially toward the base end than the second stage flow path 51b, and is configured by a group of multiple small-diameter communicating holes arranged radially and spaced apart in the circumferential direction. In this embodiment, the third stage flow path 51c is configured by eight through holes that are spaced apart in the circumferential direction and extend radially in the radial direction at positions that are circumferentially offset by 22.5° from the center of the through holes in the second stage flow path 51b. Therefore, the angle between the centers of the through holes that are adjacent in the circumferential direction is 45°.

[0026] 2 and 4, the adjuster 60 is a solid cylindrical shaft member that has, in order from the tip, a solid cylindrical throttle portion 61, an O-ring mounting groove 62, a male spigot portion 63, and a male thread portion 64. The O-ring is not shown. As shown in FIG. 5, the adjuster 60 is coaxially mounted inside the sleeve 50 so that the throttle portion 61 at the tip of the adjuster 60 changes the opening amount of the throttle channels 51a to 51c in the throttle channel portion 51. Adjuster 60 The throttle portion 61 at the tip protrudes into the throttle flow passage portion 51 of the cylindrical sleeve 50, and is therefore always supported in a double-supported state.

[0027] The throttle portion 61 and the spigot male portion 63 have the same diameter, and are spigot-fitted to the spigot female portion 55 of the sleeve 50 so as to be slidable in the axial direction. The male thread portion 64 is threadedly engaged with the female threads 56 in the nut portion 54 of the sleeve 50, and a nut 70 is threadedly attached to the base end side of the nut portion 54 so as to maintain the position where it is threaded onto the sleeve 50.

[0028] The adjuster 60 changes the amount of threading of itself into the sleeve 50 to slide the throttling section 61 in the axial direction, thereby sequentially blocking and opening the multiple stages of throttling flow paths 51a to 51c formed in the throttling flow path section 51 at the tip of the sleeve 50, thereby adjusting the flow rate passing through to the low-pressure circuit 127. The valve adjuster 40 of this embodiment ensures a step-like oil volume characteristic as shown in FIG. 9, such that the passing flow rate is (1) small oil volume (approximately 15% reduction), (2) standard oil volume, and (3) large oil volume (approximately 15% increase).

[0029] In this embodiment, as shown in FIGS. 4 and 5, when the screw position of the adjuster 60 in the axial direction relative to the sleeve 50 is adjusted, the base end of the adjuster 60 is provided with a plurality of screw holes 51a, 51b, 51c corresponding to the communication positions of the respective stages of the flow paths 51a, 51b, 51c. adjuster Marks indicating the set positions of the stages 51a, 51b, and 51c are provided in a line in the axial direction at positions that protrude from the base end of the stage 60 in order and are visible. In this embodiment, until the flow rate reaches each of the stages 51a, 51b, and 51c of the step-by-step flow rate characteristics, adjuster There are three step surfaces that serve as markers for turning 60 (E: Economy, P: Power, HP: High Power).

[0030] With this configuration, the adjuster 60 of this embodiment has its own axial screwing position relative to the sleeve 50 adjusted, thereby sequentially connecting the flow paths 51a, 51b, 51c of the multi-stage throttling flow path section 51, thereby gradually changing the opening amount to the low-pressure circuit 127 depending on the screwing position. As a result, in this embodiment, the restriction on the discharge passage 128 side for adjusting the amount of oil is formed by using a sleeve 50 with small diameter communicating holes arranged radially and in multiple stages, and an adjuster 60, and three types of oil amount adjustment are realized by selecting the passage area to the low pressure circuit 127 side.

[0031] In particular, in this embodiment, as shown in Figures 5 to 8 showing the adjustment state by the valve adjuster, the amount of axial movement of adjuster 60 is set so that when the communication state with low-pressure circuit 127 shifts from one stage to another adjacent stage due to axial movement of adjuster 60, the screw engagement position of adjuster 60 with respect to sleeve 50 becomes a position where it has rotated one or more times.

[0032] Generally, hydraulic breakers are designed to operate properly at an operating pressure of 16 MPa to 18 MPa. In the breaker body 10 of this embodiment, the target range of operating pressure is assumed to be 17 MPa ± 1 MPa, with the intended performance being achieved at 18 MPa, and the range is set to -2 MPa to 0 MPa with 18 MPa as the base. Therefore, the target operating pressures are set to achieve the intended performance at 18 MPa to 17 MPa.

[0033] As described above, in the valve adjuster 40 of this embodiment, for each target operating pressure, the throttle flow path section 51 has multiple stages of flow paths 51a, 51b, 51c, which are a three-stage configuration having a first stage flow path 51a formed in a crown shape at a first circumferential position on the tip surface of the sleeve 50, a second stage flow path 51b provided at a second circumferential position spaced axially closer to the base end than the first stage flow path 51a, and a third stage flow path 51c provided at a third circumferential position spaced axially closer to the base end than the second stage flow path 51b. With the valve adjuster 40 of this embodiment, the operating pressure can be set to the rated pressure at any stage. Correspondingly, with the valve adjuster 40 of this embodiment, three stepped surfaces are provided at the end of the male thread portion 64 of the adjuster 60 as markers for the step position of the adjuster 60, making it easy to identify the stage set to Economy / Power / High Power.

[0034] [Actions and Effects] Next, the operation and effects of the valve adjuster 40 of this embodiment will be described. When this type of hydraulic breaker is attached to the tip of the arm of a work machine such as a hydraulic excavator, the hydraulic pressure supplied by the work machine is set optimally based on the specifications of the hydraulic breaker, and adjusted to a state where the hydraulic breaker can operate properly.

[0035] When using a hydraulic breaker attached to the end of a work machine's arm, if the operating pressure exceeds the appropriate pressure, the work speed will increase, but the running costs will decrease due to premature wear of consumables and overload. Furthermore, if the pressure is not appropriate, oil seals will deteriorate prematurely, making oil leaks more likely to occur. Therefore, it is important to set the operating pressure at the appropriate level.

[0036] Here, the operating pressure of the hydraulic breaker 10 is determined by the oil consumption amount, which is related to the number of strikes of the built-in piston 15 relative to the input power. Conversely, if you know whether the discharge oil amount setting on the hydraulic excavator is small, standard, or large, you can uniquely determine the amount of throttling on the low-pressure circuit side that can maintain the rated pressure on the hydraulic breaker side.

[0037] 1, during the retraction stroke of the piston 15, the pressure oil in the piston rear chamber 11b flows into the low-pressure circuit 127 side via the control valve 30. At this time, the role of the valve adjuster 40 is to throttle the flow rate into the low-pressure circuit 127 side, thereby slowing down the retraction speed of the piston 15 and reducing the number of strokes, thereby ensuring the desired operating pressure. If the valve adjuster were not attached to the discharge passage 128, the operating pressure of the breaker body 10 would be low, causing the behavior of the breaker body 10 to become unstable and preventing the desired output from being obtained. In other words, when focusing on a hydraulic excavator, the output of the hydraulic excavator is expressed by the following [Equation 1]. (Power output of hydraulic excavator) = (Flow rate) * (Pressure) [Equation 1]

[0038] If the breaker body 10 does not have resistance to the low-pressure side (i.e., a valve adjuster), the hydraulic oil will flow to the low-pressure side without restriction. This will result in a lower pressure (operating pressure) applied from the hydraulic excavator. Furthermore, in hydraulic breakers, as shown in the following [Equation 2], the output is increased by increasing the energy per impact (number of impacts in a drifter) in the breaker body 10. (Hydraulic breaker output) = (Number of impacts) * (Impact energy) [Equation 2]

[0039] In hydraulic breakers, the pressure-receiving area is large to ensure the energy of each impact. Therefore, if resistance is not provided on the low-pressure side, the hydraulic oil will flow to the low-pressure side without restriction. As a result, the retraction speed increases like a drifter, and the number of impacts increases.

[0040] As the number of blows increases, the amount of oil consumed increases due to the relationship (oil consumption) = (number of blows) * (oil consumption per blow), and therefore the flow rate also increases. When the flow rate increases, the hydraulic oil pressure decreases according to the above hydraulic excavator output [Equation 1]. 1) If the flow rate through the throttle provided by the valve adjuster is small, the resistance to oil flow in the piston rear chamber 11b increases, which reduces the retraction speed of the piston 15 and reduces the number of strokes of the hydraulic breaker. 2) Conversely, if the flow rate through the throttle provided by the valve adjuster is large, the resistance to oil flow in the piston rear chamber 11b decreases, increasing the retraction speed of the piston 15 and increasing the number of strokes of the hydraulic breaker. Therefore, the role of the valve adjuster is to ensure an appropriate operating pressure by restricting the flow rate to the low pressure side on the breaker body 10 side so that too much hydraulic oil does not flow to the low pressure side.

[0041] Under this mechanism of action, as mentioned above, conventional valve adjusters have a structure in which the flow rate changes proportionally depending on the degree of the throttle portion protruding into the communication passage connected to the low-pressure circuit, so there is variation depending on the number of rotations of the sleeve that is screwed in, making it difficult to reliably set the desired flow rate at the throttle portion, which affects the stability of the operating pressure.Furthermore, in the case of fixed throttles, it is necessary to have multiple types of throttles, which causes the problem of being troublesome when dealing with rental machines that are installed on various excavators.

[0042] In contrast, in the valve adjuster 40 of this embodiment, as described above, the sleeve 50 has multiple stages of throttle passages 51a-c spaced apart in the axial direction at its tip, and is attached to the breaker body 10 so that the throttle passages 51a-c are located within the discharge passage 128 connected to the low-pressure circuit 127. The adjuster 60 has a throttle section 61 at its tip that is coaxially mounted within the sleeve 50 so as to change the opening amount of the throttle passages 51a-c, and its axial screwing position relative to the sleeve 50 can be adjusted so that the multiple stages of throttle passages 51a-c are connected in sequence according to the screwing position, thereby gradually changing the flow rate passing through to the low-pressure circuit 127.

[0043] In more detail, Fig. 5 shows the adjuster 60 in a fully closed state. In the state shown in Fig. 5, the passing flow rate corresponds to the state indicated by reference symbol 1 in Fig. 9. The first-stage flow path 51 of this embodiment is formed so as to maintain a minimum flow rate that does not fully close the opening of the throttle flow path portion 51 of the sleeve 50, even when the adjuster 60 is in the position where it is most tightened relative to the sleeve 50. The minimum passing oil rate of the throttle provided by the valve adjuster 40 of this embodiment is set by connecting the outer circumferential tip of the throttle flow path portion 51 of the sleeve 50 to the discharge passage 128 side.

[0044] When the screwing position of the adjuster 60 is moved from this state toward the axial base end, the concave arc groove of the crown-shaped first stage flow path 51a gradually opens, and the flow rate gradually increases from the state shown by reference numeral 1 to reference numeral 2 in Fig. 9. Thereafter, no change occurs in the flow path until the state shown by reference numeral 3 in Fig. 6, which is just before the second stage flow path 51b opens, and the flow rate is maintained at a low level (E).

[0045] In this embodiment, the amount of axial movement of the adjuster 60 when the first stage flow path 51a and the second stage flow path 51b communicate with the discharge passage 128 is set to a position where the screw engagement position of the adjuster 60 has rotated one or more times. As shown in FIG. 6, a mark indicating the step position of the adjuster 60 is provided to protrude from the upper end surface of the nut 70 so that E: Economy is visible.

[0046] Then, from this state adjuster When the screwing position of 60 is moved further toward the base end in the axial direction, the second stage flow path 51b gradually opens, and the flow rate gradually increases from the state shown by reference numeral 3 to the state shown by reference numeral 4 in Fig. 9. Thereafter, no change occurs in the flow path until the state shown by reference numeral 5, which is just before the third stage flow path 51c is connected as shown in Fig. 7, and the flow rate is maintained at the standard (P) state.

[0047] In this embodiment, the amount of axial movement of the adjuster 60 when the second stage flow path 51b to the third stage flow path 51c communicates with the discharge passage 128 is set to a position where the screw engagement position of the adjuster 60 has rotated one or more times. As shown in FIG. 7, a mark indicating the step position of the adjuster 60 is provided to protrude from the upper end surface of the nut 70 so that (P: Power) is visible.

[0048] Thereafter, when the screwing position of the adjuster 60 is further moved from this state toward the base end in the axial direction, the third stage flow path 51c gradually opens, and the flow rate gradually increases from the state indicated by reference numeral 5 to 6 in Fig. 9. Thereafter, no change occurs in the flow path after the state indicated by reference numeral 6 in Fig. 8, where the third stage flow path 51c is fully open, and the flow rate is maintained at a high (HP: High Power) state.

[0049] At this time, in the example of this embodiment, the third stage flow path 5 1c The amount of axial movement of the adjuster 60 until it communicates with the discharge passage 128 in a fully open state is determined to be a position where the screw engagement position of the adjuster 60 has rotated one or more times. As shown in Figure 8, the mark for the step position of the adjuster 60 is protruded from the upper end face of the nut 70 so that (HP: High Power) is visible.

[0050] Thus, according to the valve adjuster 40 of this embodiment, the multiple-stage throttle flow paths 51a to 51c provided in the sleeve 50 are sequentially connected depending on the screw-in position of the adjuster 60, thereby making it possible to gradually change the flow rate passing through to the low-pressure circuit 127, and therefore the operating pressure of the hydraulic breaker can be easily set to the specified pressure.

[0051] Furthermore, according to the valve adjuster 40 of this embodiment, the amount of axial movement of the adjuster 60 is set so that when the state in which each stage of the multi-stage throttle flow paths 51a-c is connected to the discharge passage 128 changes from one stage to another adjacent stage due to axial movement of the adjuster 60, the screw engagement position of the adjuster 60 with respect to the sleeve 50 becomes a position where it has rotated one or more revolutions, which is advantageous in clearly distinguishing the setting positions of the stages 51a, 51b, 51c which are changed in stages.

[0052] Furthermore, in the valve adjuster 40 of this embodiment, each stage 51a, 51b, 51c of the multi-stage flow path provided at the plug tip is composed of a set of multiple through holes that are circumferentially spaced apart and communicate radially at the same position on the same circumference in each stage 51a, 51b, 51c. Therefore, even if there is variation in the number of rotations of the sleeve 50 that is screwed into the discharge passage 128 and a circumferential positional deviation occurs when the sleeve 50 is fastened to the discharge passage 128, the same shape of flow path is set for each phase according to the number of radial divisions, and therefore the positional deviation can be substantially tolerated.

[0053] Furthermore, in the valve adjuster 40 of this embodiment, when the axial threading position of the adjuster 60 relative to the sleeve 50 is adjusted, the base end of the adjuster 60 has marks that protrude from the base end of the sleeve 50 in order to correspond to the communication positions of each of the stages 51a, 51b, 51c of the multi-stage flow path, and are provided in visible positions (that is, positions that protrude beyond the end face of the nut 70 in the example of this embodiment) to indicate the setting positions of each of the stages 51a, 51b, 51c, which provides excellent workability in terms of easily setting the operating pressure of the hydraulic breaker to the specified pressure.

[0054] In particular, in the valve adjuster 40 of this embodiment, the multiple stages of flow paths 51a, 51b, 51c include a first stage flow path 51a formed in a crown shape at a first circumferential position on the tip surface of the sleeve 50, a second stage flow path 51b provided at a second circumferential position spaced axially closer to the base end than the first stage flow path 51a, and a third stage flow path 51c provided at a third circumferential position spaced axially closer to the base end than the second stage flow path 51b.Therefore, if it is known whether the discharge oil volume setting on the hydraulic excavator side is small, standard, or large, the configuration is extremely excellent as it allows the amount of throttling to the low-pressure circuit 127 side that can maintain the rated pressure on the hydraulic breaker side to be uniquely determined.

[0055] Furthermore, in the valve adjuster 40 of this embodiment, the first stage flow path 51a is formed so as to maintain a minimum flow rate that does not completely close the opening of the throttling flow path of the sleeve 50, even when the adjuster 60 is in the most tightened position relative to the sleeve 50. Therefore, in consideration of the safety design concept (foolproof / fail-safe), safety is ensured even when the adjuster 60 is operated in a fully tightened state.

[0056] As described above, according to the valve adjuster 40 of this embodiment, multiple stages of flow paths 51a, 51b, and 51c are provided at intervals in the axial direction as throttle flow paths at the tip of the sleeve 50, and depending on the screwing position of the adjuster 60, the multiple stages of flow paths 51a, 51b, and 51c are sequentially connected to the discharge passage 128, thereby making it possible to change the flow rate passing through the low-pressure circuit 127 in stages.

[0057] Therefore, when the hydraulic breaker is replaced with a different work machine, it is easy to set the throttle amount to suit that machine, and the reproducibility of setting the throttle amount to suit that machine can be improved. Note that the valve adjuster for a hydraulic breaker according to the present invention is not limited to the above embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0058] 10 Breaker body 11 cylinders 11a Piston front chamber 11b Piston rear chamber 12 Front Head 13 Buckhead 14 Chisel 15 pistons 16 Cylinder liner 17 Seal retainer 20 through bolt 21 Accumulator 30 Control Valve 40 Valve adjuster 50 sleeves 51 throttle flow path section 51a First stage flow path 51b Second stage flow path 51c Third stage flow path 52 Male thread 53 O-ring mounting groove 54 Nut part 55 Female spigot 56 Female thread 60 adjuster 61 Constriction section 62 O-ring mounting groove 63 Inro Obe 64 Male thread 65 Landmark 70 Nut 101 Valve housing 101d Mounting hole 105 Valve Space 106 Valve 124 High-voltage circuit 127 Low-voltage circuit 128 Discharge passage (communication passage) 150 plug 160 adjuster P Hydraulic pump T Tank

Claims

1. A valve adjuster for a hydraulic breaker that is attached to a breaker body to adjust the amount of pressure oil supplied from the outside, a cylindrical sleeve interposed in a communication passage connected to a low-pressure circuit on the breaker body side; and an adjuster threadedly attached to the sleeve so that the threaded position in the axial direction can be adjusted, The sleeve has a tip end with a plurality of stages of throttle passages spaced apart in the axial direction, with non-communicating portions formed between the throttle passages, and is attached to the breaker body so that the plurality of stages of throttle passages are located within the communicating passage, The adjuster is a valve adjuster for a hydraulic breaker, in which a throttle portion at the tip thereof is configured to sequentially connect the flow paths of the multiple-stage throttle flow paths to gradually change the flow rate passing through to the low-pressure circuit according to the screwing position.

2. 2. The valve adjuster for a hydraulic breaker according to claim 1, wherein each stage of the multiple flow paths is set so that when a communication state with the low-pressure circuit is transferred from one stage to another adjacent stage due to axial movement of the sleeve, the axial movement amount of the adjuster is set so that the screw engagement position of the adjuster with respect to the sleeve is a position where it has rotated one or more times.

3. 3. The valve adjuster for a hydraulic breaker according to claim 1, wherein each stage of the multi-stage throttle flow passage provided at the tip of the sleeve is constituted by a set of a plurality of communication holes that are circumferentially spaced apart at the same circumferential position in each stage and communicate in the radial direction.

4. 4. The valve adjuster for a hydraulic breaker according to claim 1, wherein the base end of the sleeve is provided with marks that indicate set positions of each stage, the marks protruding from the base end of the sleeve in order to correspond to communication positions of each stage of the multiple-stage throttle flow path when the axial screwing position of the valve adjuster for a hydraulic breaker relative to the sleeve is adjusted, and the marks indicate set positions of each stage.

5. 5. The valve adjuster for a hydraulic breaker according to claim 1, wherein the multi-stage throttle flow passage comprises: a first-stage flow passage formed in a crown shape at a first circumferential position on the tip surface of the sleeve; a second-stage flow passage provided at a second circumferential position spaced apart from the first-stage flow passage toward the base end in the axial direction; and a third-stage flow passage provided at a third circumferential position spaced apart from the second-stage flow passage toward the base end in the axial direction, and wherein no flow passages are provided between these three-stage flow passages.

6. 6. A valve adjuster for a hydraulic breaker according to claim 5, wherein the first stage flow path is formed to maintain a minimum flow rate that does not completely close the flow rate passing through the throttling flow path of the sleeve to the low-pressure circuit, even when the adjuster is in a position where it is most tightened relative to the sleeve.

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