Hydraulic control device

Abstract

To provide a hydraulic control device which can operate stably by suppressing vibration (oil vibration) by an oil passing an oil passage.SOLUTION: A hydraulic control device 1 includes an oil passage 20 comprising an upper side oil passage 21 and a lower side oil passage 22, and includes a valve body 10 in which an oil can circulate between the upper side oil passage 21 and the lower side oil passage 22. The valve body 10 includes an upper cover 30, and an inside communication hole 12A for communicating the upper side oil passage 21 and the lower side oil passage 22. The upper cover 30 has flexibility, and is fixed to an upper surface side of the valve body 10 by a fastening member 31. The upper side oil passage 21 has an outside communication hole 13 for communicating with the outside of the valve body 10. In the outside communication hole 13, an opening end is covered by the upper cover 30, and the outside communication hole communicates with the outside through a gap formed between itself and the upper cover 30. The outside communication hole 13 has a diameter capable of ventilating, and capable of suppressing passing of the oil.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydraulic control device provided in a transmission or the like. [Background technology]

[0002] Conventionally, in transmissions such as CVTs (Continuously Variable Transmissions), a hydraulic control device is provided to operate each component hydraulically (see, for example, Patent Document 1). The hydraulic control device has a valve body in which an oil passage is formed. The valve body is disposed, for example, at the bottom of a case that houses the CVT, and an oil pump driven by engine power or the like is disposed inside the case. In addition, a strainer for filtering oil is disposed between the oil pump and the valve body. When the oil pump is driven, oil inside the case is sucked up. The sucked up oil is filtered by the strainer and sent to each component. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-85516 Summary of the Invention [Problem to be solved by the invention]

[0004] The valve body described in Patent Document 1 is divided into two layers, an upper body and a lower body. Oil passages are formed in each of the upper body and the lower body, and the oil passages in the upper body and the lower body are connected to each other. Therefore, in the valve body described in Patent Document 1, oil flows between the oil passages in the upper body and the oil passages in the lower body as needed.

[0005] However, the valve body described in Patent Document 1 has a sealed upper end to prevent oil from leaking from the upper end of the upper body. Therefore, with the valve body described in Patent Document 1, for example, if air gets mixed into the oil, the oil has no escape route, causing oil-induced vibrations (also known as oil vibrations). As a result, fluctuations in the required oil pressure occur, raising concerns about malfunctions of various components. For example, in a CVT, if the oil pressure supplied to the primary and secondary pulleys decreases due to oil vibrations, the belt clamping pressure may decrease, potentially causing belt slippage.

[0006] Therefore, an object of the present invention is to provide a hydraulic control device that can operate stably by suppressing vibrations (oil vibrations) caused by oil passing through oil passages. [Means for solving the problem]

[0007] (1) The hydraulic control device of the present invention, which is provided to solve the above-mentioned problems, is a hydraulic control device having an internal oil passage consisting of at least two layers, an upper oil passage and a lower oil passage, and a valve body that allows oil to flow between the upper oil passage and the lower oil passage, wherein the valve body has an upper cover that covers at least a portion of the upper surface and an internal communication hole that communicates the upper oil passage and the lower oil passage, the upper cover is formed of a flexible plate-like member and is fixed to the upper surface side of the valve body by tightening with at least one fastening member, the upper oil passage has an external communication hole on the upper surface side of the valve body that communicates with the outside, and the opening end of the external communication hole is covered by the upper cover and communicates with the outside through a gap formed between the opening end and the upper cover.

[0008] In the above-described hydraulic control device, the upper oil passage and the lower oil passage are connected by an internal connecting hole, and the upper oil passage has an external connecting hole on the upper surface side of the valve body that connects to the outside. Therefore, if air is mixed in the oil passing through the oil passage inside the valve body, the air is discharged to the outside of the valve body. As a result, the above-described hydraulic control device can suppress oil vibrations caused by the passage of oil containing air.

[0009] In the above-described hydraulic control device, the open end of the external communication hole is covered with an upper cover, which is formed of a flexible plate-like member. The upper cover is fixed to the upper surface of the valve body by fastening with at least one fastening member. Therefore, the upper cover bends a predetermined amount when fastened with the fastening member, forming a gap communicating with the outside between the open end of the external communication hole and the upper cover. This allows the above-described hydraulic control device to suppress oil leakage using the upper cover and to discharge air mixed in the oil to the outside of the valve body. As a result, the above-described hydraulic control device can suppress oil leakage and oil vibrations. This allows the above-described hydraulic control device to supply oil at an appropriate hydraulic pressure to each component connected to the oil passage, thereby suppressing malfunctions of each component (e.g., belt slippage in a CVT).

[0010] Here, the oil passage needs to be formed in at least two layers, and may be formed in three or more layers. The oil passage can be formed in various shapes and sizes depending on the hydraulic pressure, etc. The oil passing through the oil passage can be any of various compositions, such as lubricating oil or hydraulic oil. The valve body can be formed in various shapes and sizes, and can be made of various materials. The upper cover can be formed from various flexible members (e.g., thin steel plates) as long as it can form a gap that connects the external communication hole to the outside when fastened with fastening members (e.g., bolts). The upper cover can be formed in various shapes, sizes, thicknesses, etc. depending on the shapes of the valve body and the oil passage. The upper cover can be disposed in various locations depending on the location of the external communication hole. The external communication hole can be formed in various shapes (e.g., linear, bent, curved) that allow ventilation. The external communication hole can be formed in various opening shapes (for example, circular, elliptical, rectangular, polygonal) that allow ventilation. The opening diameter of the external communication hole can be various diameters as long as oil leakage does not occur.

[0011] (2) In the hydraulic control device of the present invention described above, the valve body is preferably formed of at least two layers, an upper body and a lower body, and the upper oil passage is formed in the upper body, and the lower oil passage is formed in the lower body.

[0012] In the above-described hydraulic control device, the valve body can be formed separately into an upper body and a lower body, which facilitates the formation of oil passages in the valve body. Here, the oil passages may be formed, for example, at the boundary between the upper and lower bodies (the underside of the upper body and the upper side of the lower body), or at the upper side of the upper body or the underside of the lower body. In such cases, the oil passages can be formed in each of the upper and lower bodies by oil-tightly covering the open ends of the oil passages with a cover, plate, or the like. In this way, in the above-described hydraulic control device, the oil passages can be formed from the surface side of the valve body, which facilitates the formation of the oil passages.

[0013] (3) In the hydraulic control device of the present invention described above, the external communication hole may have a diameter that allows ventilation with the outside and that prevents the oil from passing through.

[0014] By adopting such a configuration, the above-described hydraulic control device can suppress oil leakage and discharge air mixed in the oil to the outside through the external communication hole.

[0015] (4) In the hydraulic control device of the present invention described above, the external communication hole is formed a first predetermined distance inward from the end of the upper cover, and the first predetermined distance is preferably set according to the magnitude of the hydraulic pressure applied to the oil passage.

[0016] By configuring the hydraulic control device as described above, it is possible to suppress oil leakage, suppress oil vibrations, and appropriately control the hydraulic pressure. Here, for example, when the hydraulic control device is used in a location where the hydraulic pressure of the supplied oil is high (e.g., a CVT), the first predetermined distance can be set to a large value. This allows the hydraulic control device to suppress the gap between the external communication hole and the upper cover from widening due to the hydraulic pressure, thereby suppressing the occurrence of oil leakage. On the other hand, when the hydraulic control device is used in a location where the hydraulic pressure of the supplied oil is low, the first predetermined distance can be set to a small value. In other words, when the hydraulic pressure is low, the gap between the external communication hole and the upper cover is less likely to widen, so the first predetermined distance can be set to a small value. This is expected to increase the degree of freedom in the location of the external communication hole.

[0017] (5) In the hydraulic control device of the present invention described above, the external communication hole is formed at a position spaced a second predetermined distance from the fixed position of the upper cover by the fastening member, and the second predetermined distance is preferably set according to the magnitude of the hydraulic pressure applied to the oil passage.

[0018] By configuring the hydraulic control device as described above, it is possible to suppress oil leakage, suppress oil vibrations, and appropriately control the hydraulic pressure. Here, for example, when the hydraulic control device is used in a location where the hydraulic pressure of the supplied oil is high (e.g., a CVT), the second predetermined distance can be set to a large value. This prevents the hydraulic pressure from widening the gap between the external communication hole and the upper cover, thereby suppressing the occurrence of oil leakage. On the other hand, when the hydraulic control device is used in a location where the hydraulic pressure of the supplied oil is low, the second predetermined distance can be set to a small value. In other words, when the hydraulic pressure is low, the gap between the external communication hole and the upper cover is less likely to widen, so the second predetermined distance can be set to a small value. This is expected to increase the degree of freedom in arranging the position of the external communication hole. [Effects of the Invention]

[0019] The present invention can provide a hydraulic control device that can operate stably by suppressing vibrations (oil vibrations) caused by oil passing through oil passages. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a plan view of a hydraulic control device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional view taken along the arrow AA in FIG. [Figure 3] 2 is an enlarged view of the essential part of FIG. 1, showing the periphery of an external communication hole that constitutes the hydraulic control device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] A hydraulic control device 1 according to an embodiment of the present invention will be described below with reference to Figures 1 to 3. In this embodiment, the hydraulic control device 1 will be described as being provided inside a continuously variable transmission (also referred to as a CVT) mounted on a vehicle. Note that Figures 1 and 2 omit elements other than those necessary for describing this embodiment.

[0022] Fig. 1 is a plan view of the hydraulic control device 1 as seen from above, and Fig. 2 is a cross-sectional view taken along the line AA in Fig. 1. The hydraulic control device 1 controls the hydraulic pressure when oil (e.g., lubricating oil, hydraulic oil) is supplied to the CVT. Specifically, the hydraulic control device 1 controls the pressure of the belt by controlling the hydraulic pressure of the oil supplied to the primary pulley and the secondary pulley.

[0023] The hydraulic control device 1 has a valve body 10 as its main body. The valve body 10 is disposed at the bottom inside a case (not shown) that houses the CVT. An oil pan filled with oil and a strainer (neither of which are shown) are disposed below the valve body 10 in the case.

[0024] As shown in FIG. 2, the valve body 10 is provided with a plurality of oil passages 20 that form hydraulic paths necessary for controlling the CVT. The valve body 10 is formed of a two-layer block consisting of an upper body 11 and a lower body 15. The upper body 11 and the lower body 15 are oil-tightly joined together with bolts or the like. A strainer outlet is connected to the lower body 15 so as to communicate with a lower oil passage 22, which will be described later. Therefore, oil is sucked up by an oil pump (not shown) and filtered by the strainer. The filtered oil is supplied to the lower oil passage 22. In addition, a valve 40 (see FIG. 1; three valves in this embodiment) is connected to the oil passage 20 of the valve body 10, and the hydraulic pressure of the supplied oil is controlled by controlling the valve 40.

[0025] The upper body 11 is formed in a substantially rectangular shape in a plan view, with one corner cut out in a rectangular shape. An upper oil passage 21 constituting the present invention is formed on the lower surface side of the upper body 11. An upper oil passage 23 is also formed on the upper surface side of the upper body 11. At least a portion of the upper surface side of the upper body 11 is covered by an upper cover 30.

[0026] As shown in FIG. 1, the upper cover 30 is formed in a shape that covers at least the upper surface oil passage 23 (see FIG. 2), and is fixed to the upper surface of the upper body 11 by fastening with a plurality of fastening members 31 (e.g., bolts). The upper cover 30 is formed, for example, from a steel plate having a predetermined thickness, and is flexible enough to bend a predetermined amount when fastened with the fastening members 31. As will be described in detail later, bending of the upper cover 30 forms a predetermined gap between the opening end of the external communication hole 13 and the upper cover 30. Note that the degree of fastening of the fastening members 31 in the portions of the upper cover 30 that require oil tightness other than the opening end of the external communication hole 13 is adjusted to prevent oil leakage.

[0027] 2, the upper oil passage 21 is formed as a groove or a compartment that opens downward on the underside of the upper body 11. The underside of the upper oil passage 21 is covered by a plate 12 provided between the upper body 11 and the lower body 15, making it oil-tight. In addition, the upper oil passage 21 has an external communication hole 13 on the upper side of the valve body 10 that connects it to the outside.

[0028] The external communication hole 13 is formed linearly along the up-down direction of the upper body 11 and penetrates from the upper surface of the upper body 11 to the ceiling portion 21A of the upper-side oil passage 21. Therefore, the external communication hole 13 is in communication with the ceiling portion 21A of the upper-side oil passage 21. Furthermore, the external communication hole 13 is formed with a diameter that allows ventilation with the outside and also prevents oil from passing through. Specifically, the external communication hole 13 has a diameter of, for example, about 2 to 3 mm (2.5 mm in this embodiment). Therefore, air (air bubbles) mixed in the oil rise toward the ceiling portion 21A, pass through the external communication hole 13, and are discharged from the open end of the external communication hole 13. Meanwhile, the external communication hole 13 prevents oil from passing through the upper-side oil passage 21. Therefore, the external communication hole 13 can discharge air mixed in the oil to the outside while preventing oil leakage. The diameter of the external communication hole 13 can be changed as appropriate depending on the characteristics (for example, viscosity) of the oil used, the length and shape of the external communication hole 13, and the like.

[0029] A predetermined gap (not shown) is formed between the open end of the external communication hole 13 and the underside of the upper cover 30. The gap is formed by the upper cover 30 being bent by fastening with the fastening members 31. The gap is formed to be small enough to suppress oil leakage while still allowing air to be exhausted. As shown in FIG. 3 , the external communication hole 13 is formed inward from the end 30E of the upper cover 30 by a first predetermined distance d1.

[0030] The first predetermined distance d1 can be set according to the magnitude of the hydraulic pressure applied to the oil passage 20. For example, when the hydraulic control device 1 of the present invention is used in a location where the hydraulic pressure of the supplied oil is high (e.g., a CVT), the first predetermined distance d1 can be set large (e.g., 4.5 mm). This prevents the gap between the external communication hole 13 and the upper cover 30 from widening due to the hydraulic pressure, thereby preventing oil leakage. On the other hand, when the hydraulic control device 1 is used in a location where the hydraulic pressure of the supplied oil is low, the first predetermined distance d1 can be set small (e.g., 3 mm). In other words, when the hydraulic pressure is low, the gap between the external communication hole 13 and the upper cover 30 is less likely to widen, so the first predetermined distance d1 can be set small. This is expected to increase the degree of freedom in the location of the external communication hole 13. By appropriately setting the first predetermined distance d1, it is possible to suppress oil leakage, suppress oil vibrations, and appropriately control the hydraulic pressure. It is desirable to set the first predetermined distance d1 to a distance that maintains a sealing performance that prevents oil leakage.

[0031] The external communication hole 13 is formed at a position spaced a second predetermined distance d2 from the position at which the upper cover 30 is fixed by the fastening member 31.

[0032] The second predetermined distance d2 can be set according to the magnitude of the hydraulic pressure applied to the oil passage. For example, when the hydraulic control device 1 of the present invention is used in a location where the hydraulic pressure of the supplied oil is high (e.g., a CVT), the second predetermined distance d2 can be set large. This prevents the gap between the external communication hole 13 and the upper cover 30 from widening due to the hydraulic pressure, thereby preventing oil leakage. On the other hand, when the hydraulic control device 1 is used in a location where the hydraulic pressure of the supplied oil is low, the second predetermined distance d2 can be set small. In other words, when the hydraulic pressure is low, the gap between the external communication hole 13 and the upper cover 30 is less likely to widen, so the second predetermined distance d2 can be set small. This is expected to increase the degree of freedom in the position where the external communication hole 13 is disposed. By appropriately setting the second predetermined distance d2, it is possible to suppress oil leakage, suppress oil vibrations, and appropriately control the hydraulic pressure.

[0033] As shown in FIG. 2, the lower body 15 is formed in a block shape, and the outer shape of the upper surface is formed to be the same as the lower surface of the upper body 11. A lower oil passage 22 constituting the present invention is formed on the upper surface of the lower body 15. The lower oil passage 22 is formed as a groove or a compartment that opens toward the upper surface. The upper surface of the lower oil passage 22 is covered by a plate 12 provided between the upper body 11 and the lower body 15, making it oil-tight. The lower oil passage 22 also communicates from the upper surface to the lower surface of the lower body 15, and its lower end is connected to the discharge port of a strainer (not shown). Therefore, oil sucked up through the strainer is supplied to the lower oil passage 22.

[0034] The plate 12 is formed of a plate-like member such as a steel plate, and is disposed between the upper body 11 and the lower body 15. The plate 12 oil-tightly covers the open ends of the upper oil passage 21 and the lower oil passage 22. The upper body 11 and the lower body 15 are joined via the plate 12 with bolts or the like to form the valve body 10. The plate 12 is also formed with an internal communication hole 12A at a predetermined position, which communicates with the lower oil passage 22. The internal communication hole 12A has a diameter that allows oil to pass through, and forms part of the oil passage 20. Therefore, oil can flow mutually between the upper oil passage 21 and the lower oil passage 22. The internal communication hole 12A may be provided at each location where communication between the upper oil passage 21 and the lower oil passage 22 is required.

[0035] The above is an embodiment of the hydraulic control device 1 of the present invention. Next, hydraulic control in the hydraulic control device 1 of the present invention will be described in detail.

[0036] As shown in FIG. 2 , oil pumped up by an oil pump (not shown) is filtered by a strainer (not shown) and then supplied to a lower oil passage 22. The oil supplied to the lower oil passage 22 is sent to the upper surface of the lower body 15, passes through the internal communication hole 12A, and is sent to the upper oil passage 21. When the oil reaches the upper oil passage 21, the air mixed in the oil rises and accumulates in the ceiling portion 21A of the upper oil passage 21. The air accumulated in the ceiling portion 21A passes through the external communication hole 13 and is discharged from the open end of the external communication hole 13. The air discharged from the open end of the external communication hole 13 is discharged to the outside of the valve body 10 through the gap between the upper cover 30 and the open end. Meanwhile, the oil passing through the upper oil passage 21 is controlled to an appropriate hydraulic pressure by a valve 40 and is supplied to the CVT or the like via the lower oil passage 22, the upper oil passage 23, etc.

[0037] In this way, the hydraulic control device 1 of the present invention can discharge air mixed in oil to the outside of the valve body 10 through the external communication hole 13 provided in the upper oil passage 21. Therefore, the hydraulic control device 1 can suppress vibrations (oil vibrations) that occur when oil containing air passes through. Note that, although the present embodiment is configured to discharge air mixed in oil, the external communication hole 13 can also discharge various types of gas mixed in oil.

[0038] In this embodiment, the open end of the external communication hole 13 is covered with an upper cover 30, which is formed of a flexible plate-like member. The upper cover 30 is fixed to the upper surface of the valve body 10 by fastening with at least one fastening member 31. Therefore, the upper cover 30 is bent by a predetermined amount by fastening with the fastening member 31, and a gap communicating with the outside is formed between the open end of the external communication hole 13 and the upper cover 30. As a result, the hydraulic control device 1 suppresses oil leakage using the upper cover 30 and can discharge air mixed in the oil to the outside of the valve body 10. As a result, the hydraulic control device 1 can suppress oil leakage and oil vibrations. As a result, the hydraulic control device 1 can supply oil at an appropriate hydraulic pressure to each component connected to the oil passage 20, thereby suppressing malfunctions of each component (e.g., belt slippage in a CVT).

[0039] Furthermore, in the hydraulic control device 1 of the present invention, the valve body 10 is formed separately into the upper body 11 and the lower body 15, so that the oil passage 20 can be easily formed in the valve body 10. Here, the oil passage 20 may be formed, for example, at the boundary between the upper body 11 and the lower body 15 (the underside of the upper body 11 and the upper side of the lower body 15), or at the upper side of the upper body 11 or the underside of the lower body 15. In such a case, the oil passage 20 can be formed in each of the upper and lower bodies by oil-tightly covering the open end side of the oil passage 20 with a cover or plate. In this way, in the hydraulic control device 1 of the present invention, the oil passage 20 can be formed from the surface side of the valve body 10, making it easy to form the oil passage 20.

[0040] The above is one embodiment of the hydraulic control device 1 according to the present invention, but the hydraulic control device 1 of the present invention is not limited to the embodiment described above, and various modifications can be made.

[0041] In this embodiment, the valve body 10 is formed of two layers, an upper body 11 and a lower body 15, but the valve body 10 can be formed in various forms, such as one divided into three or more layers or one formed from a single body. The valve body 10 can also be formed in various shapes and sizes, and made from various materials. While this embodiment illustrates the hydraulic control device 1 mounted on a CVT, the hydraulic control device 1 of the present invention can be used in various hydraulic control devices, not just CVTs. The hydraulic control device 1 of the present invention can also be used in, for example, an automatic transmission (AT) or a torque converter.

[0042] The upper cover 30 can be formed from various flexible materials (for example, thin steel plates) as long as they can form a gap that connects the external communication hole 13 to the outside when fastened with the fastening members 31. The upper cover 30 can be formed into various shapes, sizes, thicknesses, etc. depending on the shapes of the valve body 10 and the oil passage 20. The upper cover 30 can be disposed in various locations depending on the position of the external communication hole 13. The fastening members 31 can be various materials (for example, bolts, pins) that can fasten the upper cover 30 and the upper body 11 together.

[0043] Furthermore, the oil passage 20 need not be formed of two layers, the upper-side oil passage 21 and the lower-side oil passage 22, but may be formed of three or more layers. The oil passage 20 can be formed in various shapes and sizes depending on the hydraulic pressure, etc. The oil passing through the oil passage 20 can be of various compositions, such as lubricating oil or hydraulic oil. The upper-side oil passage 21 need not be formed in the upper body 11, but may be formed in the lower body 15 or another body. The lower-side oil passage 22 need not be formed in the lower body 15, but may be formed in the upper body 11 or another body. The internal communication hole 12A may be provided as appropriate, or the upper-side oil passage 21 and the lower-side oil passage 22 may be directly connected without the internal communication hole 12A. The internal communication hole 12A can be formed in various shapes, sizes, or diameters, and can be disposed in an appropriate position.

[0044] In this embodiment, the external communication hole 13 has a diameter that allows ventilation to the outside and prevents oil from passing through, but the opening diameter of the external communication hole 13 can be set to various diameters as long as oil leakage does not occur. Furthermore, the opening diameter of the external communication hole 13 is not limited to the above-described embodiment and can be set to various diameters depending on the properties of the oil (e.g., viscosity). Furthermore, the external communication hole 13 can be formed in various shapes (e.g., linear, bent, curved) that allow ventilation. Furthermore, the external communication hole 13 can be formed in various opening shapes (e.g., circular, elliptical, rectangular, polygonal) that allow ventilation.

[0045] In this embodiment, the external communication hole 13 is formed a first predetermined distance d1 inward from the end 30E of the upper cover 30, but the first predetermined distance d1 can be set to various distances depending on the magnitude of the oil pressure applied to the oil passage 20. The first predetermined distance d1 can be set to various distances depending on the degree of flexibility (degree of deflection) of the upper cover 30.

[0046] In addition, in this embodiment, the external communication hole 13 is formed at a position spaced apart by the second predetermined distance d2 from the position where the upper cover 30 is fixed by the fastening member 31, but the second predetermined distance d2 can be set to various distances depending on the magnitude of the oil pressure applied to the oil passage 20. In addition, the second predetermined distance d2 can be set to various distances depending on the degree of flexibility (degree of deflection) of the upper cover 30.

[0047] The above are various embodiments and modifications of the hydraulic control device 1 according to the present invention, but the present invention is not limited to the above-described embodiments and modifications, and it will be easily understood by those skilled in the art that other embodiments are possible within the scope of the claims and the teachings and spirit of the present invention. [Industrial Applicability]

[0048] The hydraulic control device of the present invention can be used for hydraulic control of various devices, and can be preferably used for hydraulic control in transmissions such as CVTs and ATs, torque converters, etc., mounted on vehicles, etc. [Explanation of symbols]

[0049] 1: Hydraulic control device 10: Valve body 11: Upper body 12: Plate 12A: Internal communication hole 13:External communication hole 15: Lower body 20: Oil road 21: Upper oil passage 22: Lower side oil passage 23:Top side oil passage 30: Upper cover 30E: End 31: Fastening member (bolt) d1: First predetermined distance d2: Second predetermined distance

Claims

1. A hydraulic control device having an oil passage formed of at least two layers, an upper oil passage and a lower oil passage, and a valve body capable of circulating oil between the upper oil passage and the lower oil passage, an upper cover disposed on an upper surface of the valve body and covering at least a portion of the valve body; the valve body has an internal communication hole that communicates the upper oil passage and the lower oil passage, the upper cover is formed of a flexible plate-like member and is fixed to the upper surface of the valve body by fastening it with at least one fastening member, The upper oil passage has an external communication hole on the upper surface side of the valve body that communicates with the outside, The hydraulic control device, wherein the external communication hole has an open end covered by the upper cover and communicates with the outside through a gap formed between the open end and the upper cover.

2. 2. The hydraulic control device according to claim 1, wherein the external communication hole has a diameter that allows ventilation to the outside and that prevents the passage of the oil.

3. the external communication hole is formed a first predetermined distance inward from an end of the upper cover, 3. The hydraulic control device according to claim 1, wherein the first predetermined distance is set in accordance with the magnitude of hydraulic pressure applied to the oil passage.

Images