Flow control valve device with needle valve protection function and hydraulic impact device

Abstract

To provide a flow control valve device with a needle valve protection function that can suppress needle valve wear with a simple structure while using a balanced piston type flow control valve with high responsiveness in flow rate adjustment, and a hydraulic impact device equipped with said flow control valve device. [Solution] The needle valve protection section 50 has a C port connected to the T port via an annular groove 123 and a low-pressure groove 128, and the connection is maintained while the front large-diameter section 122 is located inside the cushion chamber 126. As a result, the pressurized oil supplied from the P2 port flows out to the C port, and the pressing force acting on the pressure-receiving surface S3 becomes smaller than the pressing force acting on the pressure-receiving surface S4. Consequently, the valve body 51 moves to a position that blocks the P2 port and the throttle 52, and the needle valve 42 is also blocked from the high-pressure passage. Therefore, the groove 433 maintains its minimum opening.

Description

Technical Field

[0001] The present invention relates to a flow control valve device with a needle valve protection function and a hydraulic impact device equipped with the same.

Background Art

[0002] A hydraulic impact device such as a hydraulic breaker is mounted on a host machine such as a hydraulic excavator and is an impact device that performs a crushing operation by receiving hydraulic pressure input. Here, even if the host machine is of a size compatible with a hydraulic breaker, the discharge amount of the hydraulic pump changes due to the manufacturer, model, and minor changes, so the hydraulic pressure input to the hydraulic breaker also changes. In addition, in order to shorten the crushing time, the user may intentionally increase the operating hydraulic pressure or increase the amount of operating oil supplied using a host machine with a two-pump specification, and perform the crushing operation with an increased energy amount of the hydraulic pressure input. [[ID=XXX]] [[ID=XXX]]

[0003] [[ID=XXX]] Normally, if the operating hydraulic pressure of a hydraulic impact device is too low or too high within a range of about ±15%, the opening and closing means of the connection part between the piston rear chamber and the return circuit, called a known valve adjuster, can be manually operated to adjust the opening degree of the passage and keep the operating pressure within the specification. However, even when using a valve adjuster, in a host machine with a two-pump specification, the adjustment range of the adjuster may be exceeded, and the operating pressure may not be able to be kept within the specification value.

[0004] Performing a crushing operation in a state of excessive input will lead to damage to the hydraulic breaker, so a flow control valve or a pressure control valve is attached to the host machine or the hydraulic breaker main body, and adjustment is performed so that the operating hydraulic pressure is within the specification value. Generally, a direct-acting type or a balance piston type is used for the flow control valve, and a direct-acting type is used for the pressure control valve.

[0005] For example, Patent Document 1 discloses a configuration in which a pressure control device for adjusting the operating hydraulic pressure of a striking mechanism is provided in a hydraulic breaker main body, and Patent Document 2 discloses a configuration in which intermediate pressure adjustment means is provided in a hydraulic breaker. On the other hand, using a different method, for example, Patent Document 3 discloses a technique for automatically adjusting the piston stroke so that the impact force of the piston does not become excessive, even when excessive pressure is supplied in response to the hardness of the material to be crushed. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 8-323648 [Patent Document 2] Patent No. 2515206 [Patent Document 3] Patent No. 6713778 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The inventor previously used the structure disclosed in Patent Document 1 to maintain the specified pressure by attaching a pressure regulating valve to the hydraulic breaker body. In particular, to regulate the fluctuating pressure of the hydraulic breaker, a highly responsive flow control valve with a needle valve protection function that can avoid override was adopted. This system works by receiving the operating pressure of the hydraulic breaker, and when the pressure exceeds a set value, the needle valve opens, which activates the built-in spool. This expands the passage opening from the high-pressure line to the return line, relieving the excess hydraulic fluid and maintaining the pressure within the specified value.

[0008] However, during crushing zone operation and dry-firing operation, the piston is not decelerated by impact. Instead, when the piston passes the impact point and enters the cushion chamber, it decelerates rapidly, causing a sharp decrease in oil consumption, while the supply of hydraulic fluid remains unchanged. As a result, a long-duration ultra-high pressure state persists based on a single impact cycle. During this time, the opening and closing stroke of the needle valve repeatedly moves between maximum opening and closing, which tends to accelerate the wear of the needle valve over time.

[0009] To suppress such wear, flow control valves with needle valve protection functions that use needle valves employ methods such as rounding the seat surface of the needle valve and making the needle valve itself spherical to change the seat from line contact to surface contact. However, even with these measures, needle valve wear due to aging is unavoidable, and there was room for improvement.

[0010] When examining other prior art, the direct-acting pressure regulating valve disclosed in Patent Document 2 has the problem of poor responsiveness to pressure regulation by override. In other words, the opening and closing due to pressure in the section where the rear chamber is connected to a low pressure is insensitive, so there is room for improvement here as well.

[0011] Furthermore, when employing a stroke switching mechanism that corresponds to the hardness of the rock mass, as disclosed in Patent Document 3, a retaining structure for maintaining the piston stroke is essential, which makes it impossible to avoid structural complexity and tends to lead to increased manufacturing and maintenance costs.

[0012] In view of the above circumstances, the present invention aims to provide a flow control valve device with a needle valve protection function that can suppress needle valve wear with a simple structure while using a balanced piston type flow control valve with high responsiveness in flow rate adjustment, and a hydraulic impact device equipped with the flow control valve device. [Means for solving the problem]

[0013] The present invention relates to a flow control valve device with a needle valve protection function, which is mounted on the body of a hydraulic impact device and automatically adjusts the flow rate of a working fluid supplied from the outside according to the pressure of the working fluid, and is characterized by comprising: a balance piston valve that operates according to the pressure of a high-pressure passage; a needle valve that opens and closes in response to pilot pressure supplied from the high-pressure passage and switches the balance piston valve between an operable state and a fixed state; and a needle valve protection part that fixes the needle valve in a closed state while a part of the large-diameter portion of the piston housed inside the body of the hydraulic impact device that strikes the chisel is located inside a deceleration cushion chamber. The present invention also relates to a hydraulic impact device equipped with the flow control valve device with a needle valve protection function. [Effects of the Invention]

[0014] According to the present invention, while using a balance piston type flow control valve with high responsiveness in flow control, it is possible to provide a flow control valve device with a needle valve protection function that can suppress wear of the needle valve with a simple structure, and a hydraulic impact device equipped with the flow control valve device.

Brief Description of the Drawings

[0015] [Figure 1] It is a diagram showing the structure of a hydraulic breaker according to the first embodiment of the present invention. [Figure 2] It is a diagram showing the structure of a piston included in the hydraulic breaker according to the first embodiment of the present invention. [Figure 3] It is a diagram showing the structure of a switching valve included in the hydraulic breaker according to the first embodiment of the present invention. [Figure 4] It is a diagram showing the structure of (a) a flow control valve with a needle valve protection function included in the hydraulic breaker according to the first embodiment of the present invention, and (b) the structure of the valve body of the needle valve protection part. [Figure 5] It is a diagram showing (a) the hydraulic pressure connection relationship and operation of each element of the hydraulic breaker according to the first embodiment of the present invention, (b) an enlarged view of the i part of (a), and (c) an enlarged view of the ii part of (a). [Figure 6] It is a diagram showing (a) the hydraulic pressure connection relationship and operation of each element of the hydraulic breaker according to the first embodiment of the present invention, (b) an enlarged view of the iii part of (a), and (c) an enlarged view of the iv part of (a). [Figure 7] It is a diagram showing (a) the hydraulic pressure connection relationship and operation of each element of the hydraulic breaker according to the first embodiment of the present invention, (b) an enlarged view of the v part of (a), and (c) an enlarged view of the vi part of (a). [Figure 8] It is a diagram showing the structure of a hydraulic breaker according to the second embodiment of the present invention. [Figure 9] It is a diagram showing the structure of a piston included in the hydraulic breaker according to the second embodiment of the present invention. [Figure 10]FIG. (a) shows the structure of a flow control valve with a needle valve protection function, and FIG. (b) shows the structure of the valve body of the needle valve protection part, which are included in the hydraulic breaker according to the second embodiment of the present invention. [Figure 11] FIG. shows the structure of a pilot check valve included in the hydraulic breaker according to the second embodiment of the present invention. [Figure 12] FIG. shows the hydraulic pressure connection relationship and operation of each element included in the hydraulic breaker according to the second embodiment of the present invention, FIG. (b) is an enlarged view of the vii part of FIG. (a), and FIG. (c) is an enlarged view of the viii part of FIG. (a). [Figure 13] FIG. shows the hydraulic pressure connection relationship and operation of each element included in the hydraulic breaker according to the second embodiment of the present invention, FIG. (b) is an enlarged view of the ix part of FIG. (a), and FIG. (c) is an enlarged view of the x part of FIG. (a). [Figure 14] FIG. shows the hydraulic pressure connection relationship and operation of each element included in the hydraulic breaker according to the second embodiment of the present invention, FIG. (b) is an enlarged view of the xi part of FIG. (a), and FIG. (c) is an enlarged view of the xii part of FIG. (a).

MODE FOR CARRYING OUT THE INVENTION

[0016] First, the first embodiment of the present invention will be described with reference to FIGS. 1 to 7. It should be noted that both the first embodiment and the second embodiment are schematic drawings. Therefore, it should be noted that the relationship between the thickness and the planar dimensions, the ratio, etc. are different from the actual ones, and there are parts where the dimensional relationships and ratios are different between the drawings. In addition, the following embodiments illustrate devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the materials, shapes, structures, arrangements, etc. of the components in the following embodiments. In the following description, when specifying a direction, the side where the tip portion of the chisel 14 is located may be referred to as the "tip side", and the side where the back head of the outer body is located may be referred to as the "rear end side". In addition, the hydraulic pressure connection relationship between each part will be described after explaining the structure of each device.

[0017] <First Embodiment> [Structure of hydraulic breaker] The structure of the hydraulic breaker 10, which is a hydraulic impact device, will be described with reference to Figures 1 and 2. In this embodiment, the hydraulic breaker 10 uses a general-purpose hydraulic oil as the working fluid. As shown in Figure 1, the hydraulic breaker 10 is constructed by housing a piston 12 that generates striking force inside an outer body 11, fixing a back head 13 to the rear side of the piston 12 in the outer body 11, and fitting a chisel 14 to the front so as to protrude from the outer body 11. The back head 13 is filled with gas and is configured to act as a gas spring that exerts forward force when the piston 12 retracts. The inside of the piston 12 and the back head 13 are separated by a seal retainer 15. Furthermore, the accumulator 16 and valve unit 21 are fixed to the outer body 11. Since both are elements that act during the reciprocating motion of the piston 12, their details will be described later.

[0018] The chisel 14 is a component that presses its tip against the material to be crushed during operation. It is slidably held from the tip side by a front bush 17 and a front holder 18, and is capable of reciprocating within a range defined by a retaining element (not shown) that defines the stroke end on the forward side and the front holder 18.

[0019] [Piston structure and hydraulic fluid chamber configuration] As shown in Figure 2, the piston 12 has a medium diameter section 121, a large diameter front section 122, an annular groove 123, a large diameter rear section 124, and a small diameter section 125 formed from the tip side. Between the medium diameter portion 121 and the inner circumferential surface of the outer body 11, a cushion chamber 126 and a front hydraulic fluid chamber 127 are defined from the tip side. Hereafter, the front hydraulic fluid chamber 127 will be referred to simply as the "front chamber 127". The cushion chamber 126 is the area in which the inner diameter of the outer body 11 is formed to be approximately the same as the front large diameter portion 122, and is provided to decelerate the piston 12 after striking it. The front chamber 127 is the area in which the inner diameter of the outer body 11 is formed to be larger than the front large diameter portion 122.

[0020] A low-pressure groove 128 is formed between the annular groove 123 and the inner circumferential surface of the outer body 11. The low-pressure groove 128 is a hydraulic fluid chamber for obtaining the hydraulic fluid pressure used to switch the state of the valve unit 21. A rear hydraulic fluid chamber 129 is defined between the small-diameter portion 125 and the inner circumferential surface of the outer body 11. Hereafter, the rear hydraulic fluid chamber will be referred to simply as the "rear chamber 129".

[0021] [Structure of the valve unit] Next, the structure of the valve unit 21 will be described with reference to Figures 3 and 4. The valve unit 21 is mounted on the outer body 11, which is the main body of the hydraulic impact device, and consists of a known switching valve 30 that switches the direction of piston movement, and a flow control valve device 40 with a needle valve protection function according to the present invention. Hereafter, the flow control valve device with a needle valve protection function will be described simply as "flow control valve 40".

[0022] [Structure of switching valve] As shown in Figure 3, the switching valve 30 has a cylindrical valve body 32 sealed inside the valve housing 31. The valve housing 31 is provided with a pump port 33, which is the supply port for pressurized oil discharged from the pump Pp, and a tank port 34, which is the discharge port for hydraulic oil, on the upper surface of the tip side. Note that the pump port 33 is located behind the tank port 34 in Figure 3 and the following figures, and therefore is shown with the same reference numeral as the tank port 34 in the figures. A flow control valve, which will be described later, is fixed to the upper surface of the back head side.

[0023] The valve body 32 has a first communication passage 321 and a second communication passage 322 that penetrate from the outer circumferential surface to the inner circumferential surface. The first communication passage 321 connects the A1 port (described later) to the inside of the valve body 32 or the F port to the inside of the valve body 32, while the second communication passage 322 connects or disconnects the D port to the inside of the valve body 32. Furthermore, the outer circumferential portion of the valve body 32 in the first communication passage 321 and the second communication passage 322 has a pressure-receiving surface for moving the valve body. Details are omitted, but the pressure-receiving surface on the second communication passage 322 side is wider than the pressure-receiving surface on the first communication passage 321 side.

[0024] [Flow control valve] As shown in Figure 4, the flow control valve 40 comprises a known flow control unit 41 and a needle valve protection unit 50 added in the present invention, and has the function of automatically adjusting the flow rate of the working fluid supplied from outside the hydraulic breaker 10 according to the pressure of the working fluid. The flow rate adjustment unit 41 includes a needle valve 42 and a balance piston valve 43. The needle valve protection unit 50 is located upstream of the flow rate adjustment unit 41 and controls the connection state between the flow rate adjustment unit 41 and the high-pressure passage by operating the valve body 51.

[0025] The needle valve 42 is located at the downstream end of the flow control valve 40 and is connected to the high-pressure passage. When an operating hydraulic force exceeding a set value is applied to the high-pressure passage, the needle valve 42 opens the passage to the tank T, creating a hydraulic fluid pressure difference between the upstream and downstream sides of the flow control valve 40. Specifically, it comprises a valve body 421 with a tip rounded into a roughly hemispherical shape, and a valve seat 422, and the open / closed state changes depending on the position of the valve body 421. A throttle 423 is formed on the valve seat 422 and is connected to a balance piston valve 43.

[0026] The balance piston valve 43 is located between the needle valve protection section 50 and the needle valve 42. When the needle valve 42 is open, the balance piston 431 is operated by pressurized oil supplied through the needle valve protection section 50. The balance piston 431 is biased toward the needle valve protection section 50 by a spring, and in its natural state, its tip abuts against the wall of the needle valve protection section 50. The balance piston 431 also has a throttling 432 that penetrates it along its axial direction and a groove 433 having the function described below. The groove 433 limits the opening amount of the connection portion with the F port (described later) while the balance piston valve 43 is in its natural state, thereby minimizing the pressure reduction. When the pressure in the high-pressure passage rises and the valve body moves to the needle valve side to its limit, the groove 433 maximizes the opening amount and also maximizes the pressure reduction.

[0027] The needle valve protection unit 50 is equipped with a cylindrical valve body 51 and is connected to the balance piston valve 43 by a throttle 52. As shown in Figure 4(b), the valve body 51 is formed such that the area of ​​the end face on the throttle side (pressure receiving surface S1) is equal to the area of ​​the opposite end face (pressure receiving surface S2). Furthermore, the pressure receiving surface S3, which is formed on the flow rate adjustment section 41 side of the axial center, is wider than the pressure receiving surface S4, which is formed on the opposite side of the axial center. Furthermore, a communication passage 511 is formed between the pressure-receiving surface S3 and the pressure-receiving surface S4, on the side of the pressure-receiving surface S4, extending from the outer circumferential surface to the inner circumferential surface of the valve body 51. A small-diameter portion 512, which is smaller in diameter than the other parts, is formed between the pressure-receiving surface S3 and the pressure-receiving surface S1. A slit 513, which is an axial groove, is formed in part between the small-diameter portion 512 and the pressure-receiving surface S3. Furthermore, pressure-receiving surfaces S3 and S4 are formed on both sides of the valve body 51, separated by the portion where the outer diameter is largest, so that pilot pressure can be supplied from different ports.

[0028] [Hydropressure connection relationships] The connection relationships of the hydraulic pressure will be explained with reference to Figures 2 to 5. In this invention, the outer body 11 has ports A through E formed from the tip side as connection ports for the passages. Hereafter, the connection ports for the passages formed in the valve unit 21 will basically be designated with the same names as the ports A through E formed in the outer body 11. Exceptionally, the port connected to the pump Pp will be designated as the P port, and the port connected to the tank T will be designated as the T port. Each port is indicated by a single letter of the alphabet in the figure.

[0029] As shown in Figure 2, port A is located at a position that connects the hydraulic fluid passage to the front chamber 127. Ports B through D are located in a position where they are connected to the front chamber 127 when the piston 12 is positioned near the forward direction switching point (forward starting point) on the retracted side, and separated from the front chamber 127 by the front large diameter portion at other times. Port B is a port for obtaining a signal pressure to operate the piston 12 in a short stroke, and port D is a port for obtaining a signal pressure to operate the piston 12 in a long stroke, thereby controlling the operation of the valve body 32 of the switching valve 30. That is, port B is the short stroke port described in the claim, and port D is the long stroke port described in the claim. Port C is a signal port for controlling the operation of the valve body 51 of the needle valve protection portion 50, and is connected to a low-pressure passage in particular when a part of the front large diameter portion 122 is located inside the cushion chamber 126. The T port is positioned so that a portion of the front large-diameter section 122 is located within the cushion chamber 126, while it is connected to the C port and the D port by the low-pressure groove 128. The E port is located in a position that connects the hydraulic fluid passage to the rear chamber 129.

[0030] The switching valve 30 has ports A1, F, D, A2, and E formed from the tip side. Ports A1 and A2 are connected to the pump Pp. Ports A1 and A2 are also connected to port A of the outer body 11. Ports A1 and D are supply paths for pilot pressure to switch the position of the valve body 32; the position of the valve body 32 changes in accordance with the change in pilot pressure at port D. Port F is a port that is connected to tank T via the balance piston valve 43. The connections of the other passages change depending on the position of the valve body 32, and will be explained in the section on operation.

[0031] Of the flow control valve 40, the needle valve protection section 50 has ports P1, T, C, and P2 formed from the tip side, the balance piston valve 43 has ports T and F formed from the tip side, and the needle valve 42 has only a port T formed. Ports P2 and C are pilot ports as described in the claim, and in particular, port P2 serves as both a supply passage for pilot pressure to switch the position of the valve body 51 and a passage for supplying pressurized oil to the flow rate adjustment section 41. Port C is a signal port as described in the claim, and although the details will be explained in the operation section, depending on the position of the piston 12, the connection state switches between being connected to the front chamber 127, being blocked by the front large diameter section 122, and being connected to the low-pressure groove 128.

[0032] Port P1 is always connected to the high-pressure passage, and the pressure-receiving surface S4 of the valve body 51 is always supplied with pilot pressure via port P1. Similarly, port P2 is always connected to the high-pressure passage, and the pressure-receiving surface S3 of the valve body 51 is always supplied with pilot pressure via port P2. As will be explained in detail in the section on operation, under normal conditions, the pressing force acting on the pressure-receiving surface S3 is greater than the pressing force acting on the pressure-receiving surface S4. In other words, the valve body 51 is subjected to a biasing force in the direction that connects the P2 port and the flow rate adjustment section 41, and when the C port is connected to the low-pressure passage, the high-pressure passage and the needle valve 42 are blocked against this biasing force. The space between port F and port T is part of the low-pressure passage and is configured to exert a pressure regulating effect.

[0033] [Operation / effect] The operation and function of the piston 12, switching valve 30, and flow control valve 40 will be explained with reference to Figures 5 to 8. In the figures, double arrows indicate high-pressure flow, and normal arrows indicate low-pressure flow. Note that port B of the outer body 11 is used when operating the piston 12 in a short stroke setting, and port D is used when operating it in a long stroke setting. Since neither setting affects the operation and function of the present invention, only the operation in the long stroke setting using port D will be described, and the operation in the short stroke setting using port B will not be described. (Therefore, no reference numerals are used.) Also, the outer body 11 and piston 12 are simplified and only the part I shown in Figure 2 is illustrated.

[0034] As shown in Figure 5(a), both the A1 port and the A2 port of the switching valve 30 are connected to the high-pressure passage. While the piston 12 is advancing toward the striking position, the valve body 32 is formed such that the pressure-receiving surface X on the A2 port side is larger than the pressure-receiving surface Y on the A1 port side. This difference in pressure-receiving area creates a difference in pressing force, and the first connecting passage 321 and the second connecting passage 322 are held in a position that connects the A1 port to the inside of the valve body 32. Therefore, the pressurized oil supplied from port A2 is supplied to the rear chamber 129 via the inside of the valve body 32 and port E. As mentioned above, pressurized oil is constantly supplied to the front chamber 127, but since port A of the front chamber 127 is connected to ports A1 and A2 of the switching valve 30, the pressurized oil in the front chamber 127 can move to the rear chamber 129 via the switching valve 30. In addition, since the front chamber 127 houses a medium-diameter section 121 and the rear chamber 129 houses a small-diameter section 125, the pressure-receiving area on the rear chamber 129 side is larger than that on the front chamber 127 side. As a result, the piston 12 moves forward due to the pressurized oil supplied to the rear chamber 129.

[0035] Until the piston 12 moves forward a certain distance from the reverse direction switching point, the C port of the outer body 11 is connected to the front chamber 127 and supplies pressurized oil to the C port of the needle valve protection section 50. At this time, as shown in Figure (b), pressurized oil is supplied to the C port and the P2 port, and sufficient pressing force acts on the pressure-receiving surface S3 of the valve body 51 to move the valve body 51. As a result, the valve body 51 moves to the side connecting the P2 port and the throttle 52 and is held in that position. As a result, the needle valve 42 is connected to the high-pressure passage, but as the piston 12 moves forward, the volume of the rear chamber 129 into which the pressurized oil flows increases, so the pressure does not rise enough for the needle valve 42 to operate. Therefore, the needle valve 42 remains closed during this time. During this time, as shown in Figure (c), the groove 433 is opened to less than half its original position by the balance piston 431, but the valve body 32 of the switching valve 30 isolates the F port from the high-pressure passage and the front chamber 127 and rear chamber 129, and connects it only to the low-pressure passage via the T port, so it does not affect the operation of the piston 12.

[0036] If the chisel 14 is not pressed firmly enough against the material to be crushed, or if the material is crushed and the chisel 14 moves forward, the piston 12 moves back and forth with the rear end of the chisel 14 in a position further forward than the normal striking position. In this case, as shown in Figure 6(a), the piston 12 continues to move forward without decelerating, but decelerates sharply when the front large-diameter section 122 enters the cushion chamber 126, causing a rapid decrease in the amount of pressurized oil flowing into the rear chamber 129. However, since the supply of pressurized oil from the pump Pp is maintained, the pressure of the entire fluid circuit rises rapidly.

[0037] At this time, since port D is connected to the low-pressure groove 128, the pressing force acting on the pressure-receiving surface on the port A1 side becomes dominant, causing the valve body 32 to move towards port E, blocking the passage between port E and port P, and connecting port E and port F. In other words, when the large-diameter portion of the piston 12 enters the cushion chamber 126, the switching valve 30 switches to the reverse side, connecting the rear chamber 129 to the low-pressure passage. Note that hydraulic fluid actually flows out of the rear chamber 129 to port F only after the forward movement of the piston 12 stops and it begins to move backward due to the repulsive force.

[0038] The needle valve protection section 50 has its C port connected to the T port via the annular groove 123 and the low-pressure groove 128, and the connection is maintained while the front large-diameter section 122 is located inside the cushion chamber 126. As a result, as shown in Figure (b), the pressurized oil supplied from the P2 port flows out to the C port, and the pressing force acting on the pressure-receiving surface S3 becomes smaller than the pressing force acting on the pressure-receiving surface S4. Consequently, the valve body 51 moves to a position that blocks the P2 port and the throttle 52, and the needle valve 42 is also blocked from the high-pressure passage. Therefore, as shown in Figure (c), the groove 433 maintains its minimum opening.

[0039] As shown in Figure 7(a), when the forward movement of the piston 12 stops, while a portion of the front large-diameter section 122 is located within the cushion chamber 126, a repulsive force causes the piston 12 to retract. After it exits, pressurized oil is supplied to the front chamber 127, the hydraulic fluid in the rear chamber 129 flows out to the tank T via port F, and the piston 12 retracts. Just before the piston 12 retracts and the front large-diameter portion 122 exits the cushion chamber 126, the C port of the outer body 11 is closed by the front large-diameter portion 122. At this time, as shown in Figure 7(b), pressurized oil is supplied to the C port of the needle valve protection portion 50 from the slit 513 between the valve body 51 and the inner circumferential surface of the housing. Due to the difference in pressure-receiving area between the pressure-receiving surface S3 and the pressure-receiving surface S4, the pressing force acting on the pressure-receiving surface S3 becomes superior to the pressing force acting on the pressure-receiving surface S4, and the valve body 51 moves towards the P1 port. As a result, the valve body 421 separates from the valve seat 422, allowing the balance piston 431 to move toward the needle valve 42.

[0040] At this time, in the switching valve 30, ports A1 and A2 are separated from the inside of the switching valve 30 by the valve body 32. Therefore, the entire amount of hydraulic fluid flowing in from port P is guided to the accumulator 16 and the front chamber 127, and any amount exceeding the storage capacity of the accumulator 16 acts as the reverse force of the piston 12. Then, the balance piston 431 operates in accordance with the pressure of the hydraulic fluid supplied from pump Pp, and the opening between groove 433 and port F increases to 2 to 3 times the natural state. As a result, the area of ​​the passage from rear chamber 129 to tank T is expanded, so the flow rate of hydraulic fluid consumed by the hydraulic breaker 10 per unit time increases, and the reverse speed of the piston 12 increases.

[0041] Furthermore, as the piston 12 retracts further and the C port connects to the front chamber 127, the valve body 51 is held in the position connecting the P2 port and the throttle 52, as shown in Figure 7(b). Therefore, the balance piston 431 remains operational while the piston 12 retracts. Subsequently, when the piston 12 reaches the forward / reverse switching point on the reversing side, the D port is reconnected to the front chamber 127 and becomes high pressure, causing the valve body 32 of the switching valve 30 to move towards the A1 port, the direction of movement of the piston 12 is switched, and the above-described operation is repeated.

[0042] In summary, the needle valve protection unit 50 operates to prevent pressurized oil from being supplied to the needle valve 42 of the flow control valve in the section where a portion of the front large-diameter section 122 is located inside the cushion chamber 126. Therefore, when the crushing zone is in operation or during dry-fire operation, the valve body 421 is separated from the other passages and remains closed regardless of the hydraulic fluid pressure in the high-pressure passage.

[0043] [effect] As described above, by using the flow control valve 40 according to the present invention, the valve body 421 is maintained in a closed state even when the fluid circuit is in an ultra-high pressure state. That is, while maintaining the responsiveness of pressure adjustment by the balance piston valve 43, it is possible to prevent the phenomenon of repeated maximum opening and closing caused by the ultra-high pressure acting on the valve body 421, and wear of the valve body 421 is suppressed.

[0044] In particular, the needle valve protection unit 50 according to this embodiment switches the connecting passage according to the position of the piston 12 and operates solely by fluid pressure. Therefore, it can perform needle valve protection without adding other mechanical or electrical elements, making it cheaper to manufacture and more reliable than using sensors or solenoids.

[0045] Furthermore, in this embodiment, the needle valve protection unit 50 shares a high-pressure passage connected to the valve body 421 and a high-pressure passage that supplies pilot pressure for operating the valve body 51. Therefore, it has a simpler structure than when separate passages are provided, and can be manufactured at a lower cost.

[0046] <Second Embodiment> Next, a second embodiment of the present invention will be described with reference to Figures 8 to 13. Note that in Figure 8, the pilot check valve 80 is shown in an enlarged view. Furthermore, explanations of parts that have the same structure and configuration as the first embodiment will be omitted or simplified.

[0047] As shown in Figure 8, the hydraulic breaker 10 according to the second embodiment is newly equipped with a pilot check valve 80, which is a protective switching valve, and the structure of the flow control valve 60 in the valve unit 22 is different, although details will be described later. Specifically, it differs from the first embodiment in that it uses the hydraulic fluid pressure in the pre-chamber 127 shown in Figure 9 to operate the pilot check valve 80 shown in Figure 11, which in turn operates the needle valve protection unit 70 shown in Figure 10. Therefore, the number of ports formed in the outer body 11 and the structure of the needle valve protection unit 70 are different.

[0048] [Oil pressure port on the outer body] As shown in Figure 9, the outer body 11 has a G-port added at the entrance of the cushion chamber 126. Furthermore, in the first embodiment, port C was provided between port B and port D, but in the second embodiment, port G was added and therefore port C was eliminated.

[0049] [Structure of the needle valve protection part] As shown in Fig. 10(a), the needle valve protection part 70 includes a cylindrical valve body 71, similar to the first embodiment, and is connected to the balance piston valve 43 by a throttle 72. For the valve body 71, approximately half of the range located on the throttle 72 side is formed with a larger diameter than the remaining half of the opposite side, and the range formed with a smaller diameter is covered by a sleeve 73.

[0050] As shown in Fig. (b) of the same figure, the valve body 71 is formed such that the area of the end face (pressure receiving surface S5) on the throttle 72 side is larger than the area of the end face (pressure receiving surface S6) on the opposite side (S6 < S5). Further, a pressure receiving surface S7 (constantly connected to a low pressure) is formed on the flow rate adjusting part 41 side from the axial center, and a pressure receiving surface S8 is formed on the opposite side of the pressure receiving surface S7 across the axial center. The pressure receiving surface S8 is formed to strengthen the pressing force acting on the pressure receiving surface S6 when a high pressure acts and exceed the pressing force acting on the pressure receiving surface S5 (S6 + S8 > S5).

[0051] A communication passage 711 penetrating from the outer peripheral surface to the inner peripheral surface of the valve body 71 is formed at a position between the pressure receiving surface S6 and the pressure receiving surface S8 of the valve body 71 and on the pressure receiving surface S6 side. Also, a small diameter part 712 with a smaller diameter than other parts in the range on the pressure receiving surface S5 side rather than the pressure receiving surface S8 side is formed between the pressure receiving surface S5 and the pressure receiving surface S7, and a slit 713 which is an axially long groove is formed between the pressure receiving surface S7 and the pressure receiving surface S8 in a range not reaching from the pressure receiving surface S7 to the pressure receiving surface S8.

[0052] The needle valve protection part 50 of the first embodiment has hydraulic pressure ports at four positions, while the needle valve protection part 70 of the second embodiment has hydraulic pressure ports at three positions. Specifically, they are formed in the order of the T port, the H port, and the P port from the throttle 72 side. The P port is connected to the communication passage 711 via the sleeve 73 and connects the inside of the valve body 71 to a high pressure passage. The H port is the pilot port described in the claims and is a supply path for pilot pressure to operate the valve body 71.

[0053] [Pilot check valve] The pilot check valve 80 shown in Figure 11 has a configuration unique to this embodiment, in which a pusher 82 and a check valve 83 are sealed inside the housing 81. The housing 81 has T-ports, H-ports, and P-ports oriented along the circumferential direction, and a G-port oriented along the axial direction.

[0054] Specifically, an H port is formed in the center of the housing 81, with a T port on one side of the H port and a P port on the other side. The T port and the H port, and the P port and the H port are connected to the H port via a switching passage 85 inside the housing. However, the connection between the T port and the H port is always blocked by a pusher 82, so the pilot check valve 80 is configured to only allow connection between the H port and the P port. The pusher 82 has a large-diameter portion 821 in the passage between the T port and the H port, and a medium-diameter portion 822 with a tapered seat surface extends from the H port side end. Furthermore, a pressing force portion 823 extends from the H port side end of the medium-diameter portion 822 to the passage between the H port and the P port. The end of the large-diameter portion is a pressure-receiving surface that receives pilot pressure from the G port via the throttle 84, the medium-diameter portion 822 blocks the T port and the H port by contacting the housing 81, and the small-diameter portion presses the check valve to change the open / closed state of the check valve.

[0055] The check valve 83 is located in the passage connecting the P port and the H port, and is constantly biased to seat on the housing 81 by pilot pressure supplied from the high-pressure passage. The large-diameter portion 821 of the pusher 82 is smaller in diameter than the check valve 83, and the pressing portion 823 is long enough to seat the check valve 83 in the housing 81 when it is not receiving pilot pressure from the G port. Therefore, the check valve 83 naturally blocks the H port and the P port. In other words, the pilot check valve 80 shuts off the H port and the T port in its natural state, and only connects the H port and the P port when ultra-high pressure acts on the cushion chamber 126 and presses against the pusher 82. Furthermore, a slit may be naturally formed on the circumferential surface of the pusher 82 for connecting the H port and the T port.

[0056] [Operation / effect] The operation and function of the second embodiment will be described with reference to Figures 12 to 14. Note that the outer body 11 and piston 12 are simplified and only the part II shown in Figure 9 is illustrated. As shown in Figure 12(a), while the piston 12 is moving forward, the P and G ports of the pilot check valve 80 are connected to the high-pressure passage, and the discharge pressure of the pump Pp is applied to the pusher 82 and the check valve 83. During this time, the check valve 83 remains closed because its pressure-receiving area is larger than that of the pusher 82. Therefore, the H port of the needle valve protection unit 70 is connected to the tank T via the H port of the pilot check valve 80. That is, during the natural state when no ultra-high pressure acts on the G port, the H port is connected to the low pressure.

[0057] During this time, as shown in Figure (b), the pressure-receiving surface S8 of the valve body 71 is connected to the low-pressure passage via the slit 713 of the valve body 71, and therefore does not generate a pressing force on the valve body 71. On the other hand, as shown in Figure (a), the pressure-receiving surfaces S5 and S6 receive pilot pressure supplied from the P port via the connecting passage 611, but since the area of ​​the pressure-receiving surface S6 is smaller than that of the pressure-receiving surface S5, the pressing force acting on the pressure-receiving surface S5 side prevails. As a result, in its natural state, the valve body 71 is subjected to a biasing force that moves it away from the throttle 72, and the P port and the balance piston valve 43 are connected via the throttle 72.

[0058] As a result of the above operations, pilot pressure can be supplied to the needle valve 42, and the balance piston 431 becomes operational. However, while the piston 12 is moving forward, the volume of the rear chamber 129 into which pressurized oil flows increases, as described in the first embodiment, so the pressure does not rise enough to operate the needle valve 42. Therefore, the needle valve 42 remains closed during this time. The operation of the balance piston 431 is the same as in the first embodiment, and during this time, as shown in Figure (c), the groove 433 is opened to less than half by the balance piston 431, but the valve body 32 of the switching valve 30 blocks the F port from the high-pressure passage and the front chamber 127 and rear chamber 129, and it is connected only to the low-pressure passage via the T port, so it does not affect the operation of the piston 12, as in the first embodiment.

[0059] As shown in Figure 13(a), when the piston 12 strikes the chisel 14 to crush the material to be crushed, the piston 12 moves further forward together with the chisel 14, and the front large-diameter section 122 enters the cushion chamber 126. Also, if striking is attempted without the chisel 14 being pushed in sufficiently, the piston 12 will enter the cushion chamber 126 due to inertia. Furthermore, if striking is continued after the material to be crushed has been crushed, the pressure will be insufficient, and the piston 12 will enter the cushion chamber 126. At this time, the inside of the cushion chamber 126 is closed and not connected to the return passage to the tank T. However, during this time, the piston 12 continues to move forward due to its own inertia, causing the hydraulic fluid inside the cushion chamber 126 to reach an extremely high pressure state, exceeding the discharge pressure of the pump Pp.

[0060] This ultra-high pressure is supplied from the G port of the cushion chamber 126 to the pilot check valve 80 and acts as a pressing force on the pressure-receiving surface of the pusher 82. At this time, high pressure discharged from the pump Pp is also supplied to the pressure-receiving surface of the check valve 83, but the pressing force acting on the pusher 82 is superior to the pressing force acting on the check valve 83. Therefore, the pusher 82 pushes the check valve 83, connecting the H port and the P port. Therefore, as shown in Figure (b), high pressure is supplied to the H port of the needle valve protection section 70 and acts on the pressure receiving surface S8, moving the valve body 71 to the throttling side, blocking the needle valve 42 from the P port and maintaining the closed state, and the groove 433 opening degree is also minimized as shown in Figure (c). In other words, as explained in the first embodiment, vibration (opening and closing) of the valve body 421 is prevented and protected from wear.

[0061] Subsequently, as shown in Figure 14(a), the piston 12 moves backward due to the repulsive force of the hydraulic fluid in the cushion chamber 126, and when the front large-diameter portion 122 exits the cushion chamber 126, it moves backward to the forward / reverse switching point due to the pressurized oil supplied to the front chamber 127. At this time, since only a pressure less than or equal to the discharge pressure from the pump Pp acts on the pusher 82, the check valve 83 shuts off the P port and H port of the pilot check valve 80.

[0062] Therefore, as shown in Figure (b), high pressure is not supplied to the H port of the needle valve protection unit 70, and no operating hydraulic force acts on the pressure-receiving surface S8 of the valve body 71. As a result, the valve body 71 maintains a position away from the throttle 72, pilot pressure is supplied to the needle valve 42, opening it and enabling the balance piston 431 to operate. As a result, when the piston 12 moves backward, as shown in Figure (c), the balance piston 431 operates in accordance with the pressure of the hydraulic fluid supplied from the pump Pp, and the opening between the groove 433 and the E port increases to two to three times the natural opening. That is, as in the first embodiment, the area of ​​the passage from the rear chamber 129 to the tank T is increased, so the flow rate of hydraulic fluid consumed by the hydraulic breaker 10 per unit time increases, and the backward speed of the piston 12 increases.

[0063] [effect] As described above, the flow control valve 60 according to the second embodiment can also protect the valve body 421, similar to the first embodiment. A unique advantage of this embodiment is that, because pilot pressure is supplied to the valve body 71 using the pilot check valve 80, the valve body 71 operates only when ultra-high pressure is applied to the cushion chamber 126. Therefore, if the piston 12 enters the cushion chamber 126 but ultra-high pressure is not generated, the valve body 71 will not operate. In other words, since the valve body 71 does not operate except when necessary, wear due to abrasion during operation can be suppressed to the absolute minimum. [Explanation of Symbols]

[0064] 10... Hydraulic breaker, 11... Outer body, 12... Piston, 121... Middle diameter section, 122... Front large diameter section, 123... Annular groove, 124... Rear large diameter section, 125... Small diameter section, 126... Cushion chamber, 127... Front hydraulic oil chamber (front chamber), 128... Low-pressure groove, 129... Rear hydraulic oil chamber (rear chamber), 13... Back head, 14... Chisel, 15... Seal retainer, 16... Accumulator, 17... Front bush, 18... Front holder, 21, 22... Valve unit, 30... Switching valve, 31... Valve housing, 32... Valve body, 321... First connecting passage, 322... Second connecting passage, 33... Pump port, 34... Tank port, 40, 60... Needle valve protection Function-equipped flow control valve device (flow control valve), 41...flow control section, 42...needle valve, 421...valve body, 422...valve seat, 423...throttle, 43...balance piston valve, 431...balance piston, 432...throttle, 433...groove, 50...needle valve protection section, 51...valve body, 52...throttle, 511...connecting passage, 512...small diameter section, 513...slit, 70...needle valve protection section, 71...valve body, 711...connecting passage, 712...small diameter section, 713...slit, 72...throttle, 73...sleeve, 80...pilot check valve, 81...housing, 82...pusher, 821...large diameter section, 822...medium diameter section, 823...pressing force section, 83...check valve, 84...throttle, 85...switching passage

Claims

1. A flow control valve device with a needle valve protection function, which is attached to the body of a hydraulic impact device and automatically adjusts the flow rate of the working fluid supplied from the outside according to the pressure of the working fluid, A balanced piston valve that operates according to the pressure in the high-pressure passage, A needle valve that opens and closes by receiving pilot pressure from the high-pressure passage, and switches the balance piston valve between an operable state and a fixed state, A flow control valve device with a needle valve protection function, characterized in that a needle valve protection part is provided to fix the needle valve in a closed state while a portion of the large-diameter part of the piston that is housed inside the hydraulic impact device body and strikes the chisel is located inside the deceleration cushion chamber.

2. The needle valve protection unit comprises a valve body that switches the connection state between the high-pressure passage and the needle valve, and a pilot port to which pilot pressure is supplied for operating the valve body. The flow control valve device with needle valve protection function according to claim 1, characterized in that the valve body is subjected to a biasing force in a direction that blocks the high-pressure passage and the needle valve, and has a pressure-receiving surface that moves the valve body in a direction that connects the high-pressure passage and the needle valve against the biasing force while receiving pilot pressure from the pilot port.

3. The pilot port is connected to the high-pressure passage and the signal port of the hydraulic impact device body. The flow control valve device with needle valve protection function according to claim 2, characterized in that the signal port is provided at a position in the hydraulic impact device body where a part of the large diameter portion is located inside the cushion chamber and is connected to a low-pressure passage.

4. The flow control valve device with needle valve protection function according to claim 3, characterized in that the location where the signal port is provided is further connected to the working fluid chamber on the chisel side within a predetermined range including the starting point of the forward movement of the piston, and is closed by the large diameter portion within a range from the boundary with the predetermined range to the position immediately before the large diameter portion enters the cushion chamber.

5. The piston can be set to operate in a long stroke or short stroke. The hydraulic impact device body is equipped with a long-stroke port for acquiring a signal pressure to reverse the piston's movement when the long-stroke setting is enabled, and a short-stroke port for acquiring a signal pressure to reverse the piston's movement when the short-stroke setting is enabled. The flow control valve device with needle valve protection function according to claim 3, characterized in that the signal port is provided between the long stroke port and the short stroke port.

6. The needle valve protection unit includes a valve body that switches the connection state between the high-pressure passage and the needle valve, and a pilot port to which pilot pressure is supplied for operating the valve body. The flow control valve device with needle valve protection function according to claim 1, characterized in that the valve body is provided with a biasing force in the direction connecting the high-pressure passage and the needle valve, and while receiving pilot pressure from the pilot port, the valve body is provided with a pressure-receiving surface that moves against the biasing force in the direction of blocking the high-pressure passage and the needle valve.

7. Furthermore, it is equipped with a protective switching valve that operates by receiving pilot pressure from the cushion chamber, The pilot port is connected to the protective unit switching valve, The flow control valve device with needle valve protection function according to claim 6, characterized in that the protective switching valve does not supply pilot pressure to the valve body of the needle valve protection unit when it is not supplied with ultra-high pressure pilot pressure higher than the pressure of the high-pressure passage from the cushion chamber, and supplies pilot pressure to the valve body of the needle valve protection unit when it is supplied with ultra-high pressure pilot pressure from the cushion chamber.

8. The protective switching valve has a switching passage formed inside that connects the high-pressure passage and the pilot port. The flow control valve device with needle valve protection function according to claim 7, characterized in that the switching passage is provided with a pilot check valve that is biased in a direction to block the high-pressure passage and the pilot port by pressurized oil supplied from the high-pressure passage, and connects the high-pressure passage and the pilot port when pilot pressure is supplied from the cushion chamber.

9. The flow control valve device with needle valve protection function according to any one of claims 2 to 8, characterized in that the valve body is connected to the high-pressure passage separately from the pilot port and has a pressure-receiving surface that is supplied with pilot pressure from the high-pressure passage to impart the biasing force to the valve body.

10. A hydraulic impact device characterized by comprising a flow control valve device with a needle valve protection function as described in any one of claims 1 to 8.

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