Relief valve, filter element, and filtration device

Abstract

This relief valve is disposed in a filter element that houses a filter medium between an inner cylinder and an outer cylinder and filters a liquid by causing the liquid to flow from the inner cylinder side to the outer cylinder side or from the outer cylinder side to the inner cylinder side. The relief valve is characterized by comprising: a plate having a flat surface part that is in contact with end portions of the inner cylinder and the outer cylinder and a fitting part that is fitted to the outer cylinder; a valve body that opens and closes a hole formed in the plate; a bolt that penetrates through the centers of the plate and the valve body; a spring through which the bolt is inserted; and a support member that supports one end of the spring. The relief valve is characterized in that the other end of the spring biases the valve body or the plate. This filter element has the relief valve, and this filtration device has the filter element.

Description

Relief Valve, Filter Element, and Filtering Device

[0001] The present invention relates to a relief valve, a filter element, and a filtering device.

[0002] In a hydraulic circuit that circulates hydraulic oil involved in the operation of a hydraulic device such as a construction machine, since impurities are mixed into the hydraulic oil returning to the hydraulic oil tank during use, it is necessary to perform filtration. For this reason, a filter for maintaining the hydraulic oil in a clean state is arranged. For example, inside a hydraulic oil tank that stores hydraulic oil, there is a return filter that manages the cleanliness of the entire hydraulic circuit by filtering the hydraulic oil that has circulated through the hydraulic circuit and returned to the hydraulic oil tank, and a suction filter that filters the hydraulic oil that has been filtered by the return filter and flowed into the inside of the hydraulic oil tank and causes it to flow out of the outside of the hydraulic oil tank. The hydraulic oil that has been filtered by the suction filter and flowed out of the outside of the hydraulic oil tank is sucked into the hydraulic pump and circulated through the hydraulic circuit again.

[0003] Oil filters such as return filters and suction filters are provided with a filter medium for filtering oil, and the filter medium becomes clogged due to long-term use. The oil filter is provided with a relief valve that forms a path through which the valve body opens and the oil can flow out without passing through the filter medium when the filter medium becomes clogged and the pressure in the space before penetration into the filter medium becomes an abnormal pressure of a predetermined pressure or more.

[0004] In Patent Document 1, a filter element that is detachably arranged in the element arrangement space of a filter case is described. The filter element includes an outer cylinder, an inner cylinder arranged inside the outer cylinder, a filter medium arranged on the outer periphery of the inner cylinder, an upper end plate fixed to the upper end surface of the outer cylinder, a lower end plate fixed to the lower end surface of the outer cylinder, and a relief valve as a safety valve attached to the upper end plate.

[0005] Japanese Unexamined Patent Application Publication No. 2011 - 218253

[0006] As described in Patent Document 1, the relief valve and the upper end plate were manufactured separately, and there was an assembly process in which the relief valve was attached to the upper end plate. The manufacturing process of fixing the upper end plate and then placing the relief valve on the upper end plate is complicated and involves many parts, which affects the manufacturing cost. The object of the present invention is to provide a relief valve in which the plate and valve body are integrated, which can reduce the number of parts compared to conventional products.

[0007] The relief valve of the present invention, completed for the purpose described above, is a relief valve disposed in a filter element that houses a filter material between an inner cylinder and an outer cylinder and filters liquid by flowing it from the inner cylinder side to the outer cylinder side or from the outer cylinder side to the inner cylinder side, and comprises a plate having a flat portion that abuts against the ends of the inner cylinder and the outer cylinder, and a fitting portion that fits into the outer cylinder, a valve body that opens and closes a hole formed in the plate, a bolt that penetrates the center of the plate and the valve body, a spring through which the bolt is inserted, and a support member that supports one end of the spring, wherein the other end of the spring impedes the valve body or the plate. Here, the relief valve may be characterized in that the flat portion has a recess that is recessed in the direction inward of the inner cylinder. Here, the relief valve may be characterized in that when the hydraulic fluid exceeds a predetermined pressure, the valve body moves to form a bypass that causes the liquid to flow out from the hole. Here, the relief valve may be characterized in that a gripping portion is fixed to the plate. Here, the filter element of the present invention may be a filter element characterized by comprising the relief valve. Here, the filtration device of the present invention may be a filtration device characterized by comprising the filter element.

[0008] According to the present invention, it is possible to provide a relief valve in which the plate and the valve body are integrated, which reduces the number of parts compared to conventional designs.

[0009] This figure shows a schematic of the filtration device according to this embodiment. This is a cross-sectional view of the filtration device according to this embodiment. (A) is a perspective view showing the plate-integrated relief valve according to this embodiment, and (B) is a perspective view showing the plate-integrated relief valve from a different angle. (A) is a perspective view showing the plate of the plate-integrated relief valve according to this embodiment, and (B) is a plan view showing the plate of the plate-integrated relief valve according to this embodiment. This is a cross-sectional view showing the filter element according to this embodiment. This is a cross-sectional view showing the filter element according to another embodiment. (A) is a plan view showing the valve body of the relief valve, (B) is a side view showing the relief valve under normal conditions, and (C) is a side view showing the relief valve under high pressure. (A) is a plan view showing the plate of the plate-integrated relief valve according to another embodiment, and (B) is a side cross-sectional view along line VIIIB-VIIIB showing the plate of the plate-integrated relief valve according to another embodiment. (A) is a plan view showing the plate of a plate-integrated relief valve according to another embodiment, and (B) is a side cross-sectional view taken along the line IXB-IXB showing the plate of a plate-integrated relief valve according to another embodiment. (A) is a plan view showing the plate of a plate-integrated relief valve according to another embodiment, and (B) is a side cross-sectional view taken along the line XB-XB showing the plate of a plate-integrated relief valve according to another embodiment. This is a side cross-sectional view showing the plate of a plate-integrated relief valve according to another embodiment.

[0010] The embodiments of the present invention will be described in detail below with reference to the attached drawings. <Configuration of the filtration device> Figure 1 is a schematic diagram of a filtration device 1, which is one embodiment of the present invention. The filtration device 1 is installed in a hydraulic oil tank (not shown) for temporarily storing and maintaining clean hydraulic oil circulating in the hydraulic circuit of a hydraulic device such as a construction machine (not shown). The hydraulic circuit includes, for example, a hydraulic circuit for a hydraulic cylinder used when the construction machine is working, a hydraulic circuit for travel used when the construction machine is moving, and a hydraulic circuit for turning used when the construction machine is turning. The filtration device 1 removes dust and other particles contained in the hydraulic oil. In this embodiment, the filtration device 1 is shown as an example return filter, but the filtration device of the present invention is not limited to a return filter. In addition, in this embodiment, the filtration device 1 filters hydraulic oil, but the filtration device of the present invention can also filter liquids other than hydraulic oil (such as water).

[0011] The filtration device 1 mainly comprises a filter case 10, a lid 20, a filter element 30 (see Figure 2), and a discharge section 40. The filtration device 1 is attached to a hydraulic oil tank (not shown) via a mounting section 100. The filter case 10 has an inlet hole 12a into which oil flows into the internal space. The hydraulic oil flowing in through the inlet hole 12a is guided to the filter element 30, filtered, and then discharged from the discharge hole 41 of the discharge section 40.

[0012] Figure 2 is a cross-sectional view of the filtration device 1. In Figure 2, hatching indicating the cross-section is omitted. A cylindrical filter element 30 is detachably disposed inside the filter case 10. The filter element 30 mainly consists of an outer cylinder 22, an inner cylinder 23 disposed inside the outer cylinder 22, a filter material 21 disposed on the outer circumference of the inner cylinder 23, an upper end plate 24 that abuts the upper end surface of the outer cylinder 22, a lower end plate 25 that abuts the lower end surface of the outer cylinder 22, and a relief valve 53 integrated with the upper end plate 24. The relief valve 53 includes a valve body 26, a spring 27, a bolt 28, etc.

[0013] The filter material 21 is a substantially cylindrical member having openings at both ends. The filter material 21 is formed by folding filter paper made of synthetic resin or paper into pleats and connecting both ends of the pleated filter paper to form a cylinder. An outer cylinder 22 is provided on the outside of the filter material 21, with holes formed throughout almost its entire surface for the hydraulic fluid to pass through. An inner cylinder 23 is provided on the inside of the filter material 21, with holes formed throughout almost its entire surface for the hydraulic fluid to pass through.

[0014] The outer cylinder 22 and inner cylinder 23 are substantially hollow cylindrical members with openings at both ends. Preferably, the outer cylinder 22 and inner cylinder 23 are formed using, for example, plated iron or a highly corrosion-resistant material (for example, stainless steel or resin). The filter material 21, outer cylinder 22, and inner cylinder 23 are of substantially the same height. Multiple holes formed in the outer cylinder 22 allow hydraulic fluid to communicate between the outside and inside of the outer cylinder 22, and multiple holes formed in the inner cylinder 23 allow hydraulic fluid to communicate between the outside and inside of the inner cylinder 23. The ends of the outer cylinder 22 and inner cylinder 23 may be connected.

[0015] The hydraulic fluid that flows in through the inlet hole 12a flows from the inside of the inner cylinder 23 through the hole toward the outside, and is filtered from the inside to the outside in the radial direction of the filter material 21. The hydraulic fluid filtered by the filter material 21 flows out through the hole in the outer cylinder 22 into the outer space 35. The filtered hydraulic fluid then flows out from the outer space 35 through the discharge hole 41 (see Figure 1) of the discharge section 40.

[0016] An upper end plate 24 is provided at the upper ends of the filter medium 21, outer cylinder 22, and inner cylinder 23. The upper end plate 24 has a flat portion 244 that abuts against the ends of the outer cylinder 22 and inner cylinder 23, respectively, and a fitting portion 242 that fits into the outer cylinder 22. The relief valve 53 is attached to the upper end plate 24. The bolt 28 of the relief valve 53 passes through the center of the upper end plate 24. A recess 243 in the center of the upper end plate 24 is provided with a plurality of holes 241 (see Figure 3(B)), and in the normal state, the valve body 26 covers the holes 241. In the normal state, the filtered hydraulic fluid that flows out into the outer space 35 is led to the discharge section 40 and flows out from the discharge hole 41 (see Figure 1). If the filter medium 21 becomes clogged with dust, the hydraulic pressure of the hydraulic fluid will increase. When the hydraulic fluid pressure exceeds a predetermined level, the valve body 26 of the relief valve 53 moves to form a bypass, allowing the hydraulic fluid to flow out through the hole 241. In other words, the hydraulic fluid bypasses the filter media 21 and passes through the bypass formed by the relief valve 53, without going through the path where it is filtered by the filter media 21. Under high pressure caused by clogging of the filter media 21, the bypass of the hydraulic fluid around the filter media 21 prevents failure of the filter element.

[0017] Here, a conventional relief valve will be explained using Figures 7(A) to 7(C). Figure 7(A) is a plan view showing the valve body 710 of the relief valve 700. The valve body 710 of the relief valve 700 is provided with a hole 711, allowing hydraulic fluid to flow into the interior from the outside through the hole 711. Figure 7(B) is a side view showing the relief valve 700 under normal conditions. Under normal conditions with low hydraulic pressure, the hydraulic pressure acting on the valve body is not large, so the valve body 720, which is biased by the spring 730, does not move. However, when the hydraulic pressure increases, the force pushing the valve body 720 overcomes the force extending the spring 730, and the valve body 720 moves in the direction of compressing the spring 730. Figure 7(C) is a side view showing the relief valve 700 under high pressure. As indicated by the arrows representing the movement of the hydraulic fluid in Figure 7(C), a bypass is formed through which the hydraulic fluid can pass by utilizing the space created by the movement of the valve body. In other words, when the hydraulic pressure exceeds a certain level, the relief valve 700 causes the valve body 720 to move in a direction opposite to the elastic force of the spring 730, forming a bypass. The shank 740 is inserted through the spring 730 and connected to the valve body 710. The end of the shank 740 is fixed by the support member of the filter element.

[0018] When attaching the conventional relief valve 700 described above to a filter element, a plate covering one end of the cylindrical inner and outer cylinders is first positioned, and then the relief valve is fixed to the plate. For this reason, the relief valve and the plate were assembled as separate parts.

[0019] Figure 3(A) is a perspective view showing a plate-integrated relief valve according to this embodiment, and Figure 3(B) is a perspective view showing the plate-integrated relief valve from a different angle. In this embodiment, the relief valve 53 integrated with the upper end plate has the portion corresponding to the valve body of a conventional relief valve 53 and the plate portion integrated. That is, when the valve is closed, the valve body 26 is in contact with the upper end plate 24. The valve body 26 opens and closes a hole formed in the upper end plate 24. The valve body 26 and the upper end plate 24 are preferably made of plated iron or a highly corrosion-resistant material (for example, stainless steel or resin).

[0020] The upper end plate 24 has a fitting portion 242 on its outer circumference that fits onto the cylindrical outer cylinder 22 (see Figure 2). Inside the fitting portion 242, the upper end plate 24 has a flat portion 244 that contacts the ends of the outer cylinder 22 and the inner cylinder 23. The flat portion 244 abuts against the ends of the outer cylinder 22 (see Figure 2) and the inner cylinder 23 (see Figure 2), respectively. Furthermore, the upper end plate 24 has a recess 243 in the flat portion 244 that is recessed inward towards the inner cylinder 23. A bolt 28 passes through the center of the recess 243. The head of the bolt 28 presses the valve body 26 against the recess 243 of the upper end plate 24. A spring 27 is arranged around the shank of the bolt 28. In other words, the spring 27 is arranged so that the bolt 28 can be inserted through it. One end of the spring 27 is supported by a support member 29 (see Figure 2) that is fitted onto the bolt 28. The support member 29 (see Figure 2) may be a member having a nut. The other end of the spring is supported by the upper end plate 24. Therefore, the spring 27 of the bolt 28 biases the upper end plate 24 so that it comes into contact with the valve body 26.

[0021] Furthermore, a gripping portion 31 is fixed to the upper end plate 24, and by grasping the gripping portion 31, the relief valve 53, which is integrated with the upper end plate 24, can be easily carried and installed.

[0022] Figure 4(A) is a perspective view showing the plate of the plate-integrated relief valve according to this embodiment, and Figure 4(B) is a plan view showing the plate of the plate-integrated relief valve according to this embodiment. In Figures 4(A) and (B), the relief valve 53 is not shown. Two through holes 241 are formed in the recess of the upper end plate 24. Therefore, when the pressure of the hydraulic fluid inside the filter element 30 increases, the hydraulic fluid passes through the two holes 241 provided in the upper end plate 24 and presses against the valve body 26 (see Figure 3). When the hydraulic pressure of the hydraulic fluid exceeds a certain level, and the force of the hydraulic pressure pressing against the valve body exceeds the elastic force of the spring 27 that presses the upper end plate 24 against the valve body 26, the valve body 26 moves in a direction opposite to the elastic force of the spring 27, forming a bypass that allows the hydraulic fluid to flow out from the holes 241 in the upper end plate 24.

[0023] Figure 5 is a cross-sectional view showing a filter element 30 according to this embodiment. The relief valve 53 constituting this filter element 30 is a valve that opens when the hydraulic pressure in the inner space 34 of the cylindrical inner cylinder 23 becomes high. The relief valve 53 is closed when the hydraulic pressure of the hydraulic fluid is low. The upper end plate 24 is provided with a hole 241 (see Figure 4), and the hydraulic fluid in the inner space 34 of the inner cylinder 23 flows through the hole 241 and presses against the valve body 26. When the hydraulic pressure increases due to clogging of the filter material 21 or the like, the hydraulic fluid in the inner space of the filter material 21 pushes up the valve body 26. As the valve body 26 moves upward due to the high hydraulic pressure, a bypass is formed between the valve body 26 and the upper end plate 24.

[0024] The upper end plate 24 has a roughly circular recess 243 formed on the inner diameter side of the flat portion 244, recessed against the inside of the inner cylinder 23. A bolt 28 passes through the center of the recess 243, and the head of the bolt 28 is positioned to press the valve body 26 against the upper end plate 24. A spring 27 is positioned around the shank of the bolt 28, and the upper end plate 24 is subjected to an upward force due to the elastic force of the spring 27. The recess 243 forms a flat surface from the center to near the inside of the inner cylinder 23, and the outer circumference of the recess 243 rises towards the end of the inner cylinder 23. In other words, the recess 243 forms a recess in the direction toward the inner space 34 of the inner cylinder 23. Furthermore, the upper end plate 24 forms a flat portion 244 near the ends of the inner cylinder 23, filter material 21, and outer cylinder 22, and forms a fitting portion 242 near the outer circumference of the upper end plate 24 that fits into the outer cylinder 22.

[0025] As described above, the upper end plate 24 has a shape in which the recessed portion 243, the flat portion 244, and the fitting portion 242 form an uneven surface, into which the inner cylinder 23 and the outer cylinder 22 fit. For this reason, the upper end plate 24 is fixed to the end of the filter element and has the effect of being less prone to misalignment.

[0026] As described above, the upper end plate 24 is formed as a single integrated part from the center through which the bolt 28 passes to the fitting portion 242 that fits the outer cylinder 22. Conventionally, the valve body was located in the center of the plate, but with the above configuration, the plate and the valve body are integrated, which reduces the number of parts. Furthermore, this integration makes it possible to easily attach the relief valve to the filter element.

[0027] Figure 6 is a cross-sectional view showing a filter element 30 according to another embodiment. The relief valve 53 constituting this filter element 30 is a valve that opens when the hydraulic pressure in the inner space 34 of the inner cylinder 23 increases. The relief valve 53 is in a closed state when the hydraulic pressure of the hydraulic fluid is low. The upper end plate 24 is provided with a hole 241 (see Figure 4), and the hydraulic fluid in the inner space 34 of the inner cylinder 23 flows through the hole 241 and presses against the valve body 26. However, when the hydraulic pressure of the hydraulic fluid is low, the force of the spring 27 pushing against the valve body 26 is greater, so the valve body 26 is pressed against the upper end plate 24 and remains in a closed state. However, when the hydraulic pressure in the inner space 34 increases due to clogging of the filter material 21 or the like, the hydraulic fluid in the inner space of the filter material 21 pushes up the valve body 26 against the elastic force of the spring 27. As the valve body 26 moves upward due to the high hydraulic pressure, a bypass is formed between the valve body 26 and the upper end plate 24. Since the hydraulic fluid will now pass through a bypass, it can avoid passing through the clogged filter media 21.

[0028] In the example shown in Figure 6, the valve body 26 is not located in the recess 243 as in Figure 5, but is located on the flat portion 244. Also, although the upper end plate 24 is provided with a recess 243 in both Figure 5 and Figure 6, a recess is not necessarily required, and the flat portion may extend to the center of the plate.

[0029] As described above, the upper end plate 24 is formed as a single integrated part from the center through which the bolt 28 passes to the fitting portion 242 that fits the outer cylinder 22. Conventionally, the valve body was located in the center of the upper end plate, but with the above configuration, the plate and the valve body are integrated, which reduces the number of parts. Furthermore, this integration makes it possible to easily attach the relief valve to the filter element.

[0030] Figure 8(A) is a plan view showing the plate of a plate-integrated relief valve according to another embodiment, and Figure 8(B) is a side cross-sectional view taken along line VIIIB-VIIIB showing the plate of a plate-integrated relief valve according to another embodiment. The plate-integrated relief valve of Figure 8 has a flat portion 244 that abuts against the ends of the inner cylinder and the outer cylinder, respectively, and a fitting portion 242 that fits into the outer cylinder. The recess 243 is provided with three holes 241 and three ribs 245 in addition to the central bolt hole. The three holes 241 are arranged at equal intervals of 120 degrees on the circumference of a predetermined circle, and the three ribs 245 are formed between the holes 241. The ribs 245 have the effect of supporting the opening and closing valve of the holes 241, as well as improving the mechanical strength of the recess 243.

[0031] Figure 9(A) is a plan view showing the plate of a plate-integrated relief valve according to another embodiment, and Figure 9(B) is a side cross-sectional view along the line IXB-IXB showing the plate of a plate-integrated relief valve according to another embodiment. The plate-integrated relief valve in Figure 9 has a flat portion 244 that abuts against the ends of the inner cylinder and the outer cylinder, respectively, and a fitting portion 242 that fits into the outer cylinder. The recess 243 is provided with a central bolt hole as well as two opposing crescent-shaped holes 241. An annular rib 246 is formed around the central bolt hole, with a shape that raises around the hole. In addition, a rib 247 is formed in the recess 243 so as to surround the holes 241. In the example in Figure 9, the recess 243 has a rib 246 positioned inside the holes 241 and a rib 247 positioned outside the holes 241. Ribs 246 and 247 have the effect of supporting the opening and closing valve of hole 241, as well as improving the mechanical strength of recess 243.

[0032] Figure 10(A) is a plan view showing the plate of a plate-integrated relief valve according to another embodiment, and Figure 10(B) is a side cross-sectional view taken along the line XB-XB showing the plate of a plate-integrated relief valve according to another embodiment. The plate-integrated relief valve in Figure 10 shares a common shape with the plate-integrated relief valve in Figure 9, so a detailed explanation of the shape will be omitted. The difference between the examples in Figure 10 and Figure 9 is the shape of the annular rib 246 that rises around the bolt hole in the center of the recess 243. In addition, a rib 247 is formed in the recess 243 so as to surround the hole 241. In the example in Figure 9, the recess 243 has a rib 246 positioned inside the hole 241 and a rib 247 positioned outside the hole 241. The ribs 246 and 247 have the effect of supporting the opening and closing valve of the hole 241, as well as improving the mechanical strength of the recess 243.

[0033] Figure 11 is a side cross-sectional view showing the plate of a plate-integrated relief valve according to another embodiment. In the example shown in Figure 11, a valve body 250 is positioned, supported by a rib 247 formed in a recess 243. When the pressure of the hydraulic fluid inside the filter element (not shown) increases, the hydraulic fluid passes through a hole provided in the plate of the plate-integrated relief valve and presses against the valve body 250. When the hydraulic pressure of the hydraulic fluid exceeds a certain level, and the force of the hydraulic pressure pressing against the valve body 250 exceeds the elastic force of the spring 27 that presses the plate against the valve body 250, the valve body 250 moves in a direction opposite to the elastic force of the spring 27, forming a bypass that allows the hydraulic fluid to flow out through the hole.

[0034] <Other Embodiments> Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. Furthermore, the effects of the present invention are not limited to those described in the embodiments described above. For example, the configuration of the filtration device shown in Figures 1 and 2, the configuration of the relief valve shown in Figure 3, and the configuration of the upper end plate of the relief valve shown in Figures 4, 8 to 11 are all merely examples for achieving the objectives of the present invention and are not particularly limiting. For example, in the example of Figure 8, an embodiment in which three pairs of holes and ribs are formed has been described, but in the present invention, this is not the case, and there may be four or more, and the spacing between holes and between ribs does not have to be equal. Furthermore, an embodiment without ribs is also acceptable.

[0035] 1...Filtration device, 10...Filter case, 12a...Inlet hole, 20...Lid, 21...Filter media, 22...Outer cylinder, 23...Inner cylinder, 24...Upper end plate, 25...Lower end plate, 26...Valve body, 27...Spring, 28...Bolt, 29...Support member, 30...Filter element, 31...Grip part, 34...Inner space, 35...Outer space, 40...Discharge part, 41...Discharge hole, 53...Relief valve, 241...Hole, 242...Fitting part, 243...Recess, 244...Flat part, 246, 247...Rib, 250...Valve body, 700...Relief valve, 710...Valve body, 711...Hole, 720...Valve body, 730...Spring, 740...Shank

Claims

1. A relief valve disposed in a filter element that houses a filter medium between an inner cylinder and an outer cylinder and filters liquid by flowing it from the inner cylinder side to the outer cylinder side or from the outer cylinder side to the inner cylinder side, the relief valve comprising: a plate having a flat portion that abuts against the ends of the inner cylinder and the outer cylinder, respectively, and a fitting portion that fits into the outer cylinder; a valve body that opens and closes a hole formed in the plate; a bolt that passes through the center of the plate and the valve body; a spring through which the bolt is inserted; and a support member that supports one end of the spring, wherein the other end of the spring impedes the valve body or the plate.

2. The relief valve according to claim 1, characterized in that the flat portion has a recess that is recessed in the direction toward the inside of the inner cylinder.

3. The relief valve according to claim 1, characterized in that when the liquid exceeds a predetermined pressure, the valve body moves to form a bypass that causes the liquid to flow out of the hole.

4. The relief valve according to claim 1, characterized in that a gripping portion is fixed to the plate.

5. A filter element characterized by comprising a relief valve as described in any one of claims 1 to 4.

6. A filtration device characterized by comprising the filter element described in claim 5.

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