COMPOSITE VALVE APPARATUS

A composite valve apparatus is attachable to an attachment hole. A relief-valve mechanism includes a first valve movable in the depthwise direction of an attachment hole. A thermo-valve mechanism includes a second valve fastened to a thermo actuator, and a cylindrical body that retains therein the second valve. The first valve of the relief-valve mechanism and the second valve of the thermo-valve mechanism have respective axial lines overlapping with each other. The thermo actuator is supported by the first valve, and the cylindrical body is fastened to or integrated with the first valve.

FIELD OF THE INVENTION

The present disclosure relates to a composite valve apparatus that includes a relief-valve mechanism and a thermo-valve mechanism.

BACKGROUND

A valve mechanism for controlling an oil is provided in an oil passage in a hydraulic circuit through which the oil flows. Japan Patent No. 6706028 B discloses a conventional technology for a valve mechanism.

Japan Patent No. 6706028 B discloses a hydraulic circuit that includes an oil pump which supplies an oil for lubricating and cooling an engine. The hydraulic circuit is provided with two return passages that return some of the oil discharged from the oil pump to an oil pan. A relief-valve mechanism that opens when the pressure of the oil flowing through the return passage reaches a predetermined pressure is provided in the one return passage. A thermo-valve mechanism that closes a valve when the temperature of the oil discharged from the oil pump reaches a predetermined temperature is provided in the other return passage.

Japan Patent No. 6767246 B discloses a specific structure of such a thermo-valve mechanism. The oil pump includes a pump housing that retains therein an inner gear and an outer gear. The pump housing is provided with a discharge passage through which the discharged oil flows, and an attachment hole to attach the thermo-valve mechanism. The attachment hole has the interior in communication with the discharge passage, and has one end directed outwardly.

The thermo-valve mechanism includes a thermo actuator that extends its entire length in the depthwise direction of the attachment hole as the temperature of the oil increases, a valve fastened to the lower end of the thermo actuator, a spring that applies force to the thermo actuator so as to compress the entire length of the thermo actuator, a cylindrical cylinder body that retains therein the thermo actuator, the spring, and the valve, and a plug member which supports the thermo actuator and the cylinder body, and which closes the open end of the attachment hole. The cylinder body is provided with an introducing hole that introduces the oil flowing through the discharge passage into the interior of the cylinder body, a drain hole which is opened or closed by the valve and which drains the oil introduced from the introducing hole to the exterior of the cylinder body, and a bottom portion that closes the lower end of the cylinder body.

By fitting the thermo-valve mechanism employing such a structure into the attachment hole, and by screwing the plug member into the open end of the attachment hole, the thermo-valve mechanism can be attached to the attachment hole.

When a relief-valve mechanism is further attached to the pump body of the oil pump in addition to the thermo-valve mechanism, in order to attach the relief-valve mechanism, the other attachment hole is formed. By fitting the relief-valve mechanism into such an attachment hole, and by screwing the plug member in the open end of the attachment hole, the relief-valve mechanism can be attached to the attachment hole. However, the oil pump that includes the relief-valve mechanism and the thermo-valve mechanism inevitably has the increased manufacturing costs.

An objective of the present disclosure is to provide a composite valve apparatus which includes a relief-valve mechanism and a thermo-valve mechanism, and which reduces the manufacturing costs.

SUMMARY OF THE INVENTION

A composite valve apparatus according to the present disclosure is in communication with an oil passage where an oil flows through an interior, and is attachable to an attachment hole that has one end directed outwardly. This composite valve apparatus includes:

a relief-valve mechanism that releases the oil when a pressure of the oil flowing through the oil passage reaches a predetermined pressure; and

a thermo-valve mechanism that is opened or is closed when a temperature of the oil flowing through the oil passage reaches a predetermined temperature,

wherein the relief-valve mechanism includes:a first valve that is movable in a direction becoming apart from a bottom surface of the attachment hole along a depthwise direction of the attachment hole by force applied to a pressure receiving surface that receives the pressure of the oil flowing through the oil passage;a first spring that applies force to the first valve in a direction in which the first valve becomes close to the bottom surface of the attachment hole; anda plug member which directly or indirectly supports the first spring and which closes the one end of the attachment hole,

wherein the thermo-valve mechanism includes:a thermo actuator that extends an entire length in the depthwise direction of the attachment hole as the temperature of the oil increases;a second valve fastened to the thermo actuator; anda cylindrical body that retains therein the thermo actuator and the second valve,

wherein the cylindrical body includes:an introducing hole capable of introducing the oil in an interior of the cylindrical body; anda drain hole which is opened or closed by a movement of the second valve and which is capable of draining the oil introduced from the introducing hole to an exterior of the cylindrical body,

wherein the first valve of the relief-valve mechanism and the second valve of the thermo-valve mechanism have respective axial lines overlapping with each other, and

wherein the thermo actuator abuts the first valve, and the cylindrical body is fastened to or integrated with the first valve.

More specifically, according to the present disclosure, the composite valve apparatus is in communication with an oil passage where an oil flows through an interior, and is attachable to an attachment hole that has one end directed outwardly.

The composite valve apparatus includes a relief-valve mechanism that is opened and releases the oil when a pressure of the oil flowing through the oil passage reaches a predetermined pressure. The relief-valve mechanism includes a first valve that is movable in a direction becoming apart from a bottom surface of the attachment hole along a depthwise direction of the attachment hole by force applied to a pressure receiving surface that receives the pressure of the oil flowing through the oil passage, a first spring that applies force to the first valve in a direction in which the first valve becomes close to the bottom surface of the attachment hole, and a plug member which directly or indirectly supports the first spring and which closes the open end of the attachment hole.

The composite valve apparatus also includes a thermo-valve mechanism that is opened or is closed when a temperature of the oil flowing through the oil passage reaches a predetermined temperature. The thermo-valve mechanism includes a thermo actuator that extends an entire length in the depthwise direction of the attachment hole as the temperature of the oil increases, a second valve fastened to the thermo actuator, and a cylindrical body that retains therein the thermo actuator and the second valve. The cylindrical body includes an introducing hole capable of introducing the oil in an interior of the cylindrical body, and a drain hole which is opened or closed by the second valve and which is capable of draining the oil introduced from the introducing hole.

The first valve of the relief-valve mechanism and the second valve of the thermo-valve mechanism have respective axial lines overlapping with each other.

The thermo actuator abuts the first valve. The cylindrical body is fastened to or integrated with the first valve.

That is, the composite valve apparatus has the thermo actuator and cylindrical body of the thermo-valve mechanism attached to the first valve of the relief-valve mechanism. In other words, the entire thermo valve mechanism is movable together with the first valve along the axial line. Although it is a singular unit, the composite valve apparatus has two functions.

Since the composite valve apparatus is a singular unit, the number of the attachment holes to attach the composite valve apparatus is sufficient by one. Hence, the number of the attachment holes to be formed in the pump housing can be reduced. The number of the plug members that close the attachment hole is also sufficient by one. Accordingly, the manufacturing costs can be suppressed. Moreover, the space occupied by the attachment hole in the pump housing can be reduced, increasing the degree of freedom for designing a layout to place components in the pump housing.

Preferably, the cylindrical body of the thermo-valve mechanism and the thermo actuator thereof are located at an opposite side to the pressure receiving surface of the first valve of the relief-valve mechanism in a direction of the axial line. In other words, the cylindrical body and the actuator are located between the first valve and the plug member. In comparison with a case in which the cylindrical body and the actuator are provided at the pressure-receiving-surface side of the first valve, the degree of freedom for designing the pressure receiving surface of the first valve can be improved.

Preferably, an outer circumferential surface of the cylindrical body is slidable relative to an inner circumferential surface of the attachment hole. That is, the cylindrical body can be regarded as a part of the first valve. The cylindrical body forms the thermo-valve mechanism and also forms the relief-valve mechanism. Since the cylindrical body is the structural component of both mechanisms, the number of components can be reduced. Note that the cylindrical body is a member that retains therein the thermo actuator. Accordingly, it can be regarded that the thermo actuator is retained in the first valve of the relief-valve mechanism. Hence, regarding the dimension of the attachment hole in the depthwise direction, the composite valve apparatus can be downsized.

Preferably, the first spring of the relief-valve mechanism is a compression coil spring, and the second valve of the thermo-valve mechanism is located inwardly relative to the first spring in a radial direction. That is, regarding the depthwise direction of the attachment hole, the first spring and the second valve overlap with each other. Regarding the dimension of the attachment hole in the depthwise direction, the composite valve apparatus can be downsized.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present disclosure will be described below with reference to the accompanying figures. Note that “Up” and “Dn” in the figures indicate an upper side and a down side, respectively.

First Embodiment

FIG.1illustrates a composite valve apparatus10according to a first embodiment, and a pump housing30of an unillustrated oil pump provided with an attachment hole20to which the composite valve apparatus10can be attached. Note that instead of the pump housing30, as far as an oil passage through which an oil flows is formed in the interior, and such an ail passage and the interior of the attachment hole20is in communication with each other, a structures like a cylinder block may be adopted. That is, it is not limited to the oil pump, and the composite valve apparatus10may be provided in a hydraulic circuit as appropriate.

An open end23of the attachment hole20is directed outwardly (downwardly). The diameter of the attachment hole20is constant from the open end23to a bottom surface21. In the following description, in order to facilitate understanding, a direction along the depthwise direction of the attachment hole20will be defined as a vertical direction, a direction becoming close to the bottom surface21will be defined as an upper side, and a direction becoming close to the open end23will be defined as a down side. Note that the vertical direction may be not consistent with the perpendicular direction.

An oil passage through which an oil discharged from the oil pump flows will be defined as a discharge passage31. Moreover, oil passages branched from the discharge passage31will be defined as a first discharge passage32and a second discharge passage33.

The first discharge passage32is in communication with the interior of the attachment hole20through a hole of the bottom surface21of the attachment hole20. The pump housing30is provided with a first drain passage35and a second drain passage36which drain the oil flowing from the first discharge passage32from the interior of the attachment hole20. The two drain passages35and36are located above the second discharge passage33. The two drain passages are in communication with an inner circumferential surface22of the attachment hole20.

The second discharge passage33is in communication with the interior of the attachment hole20through a hole of the inner circumferential surface22of the attachment hole20. More specifically, the second discharge passage33is orthogonal to the depthwise direction of the attachment hole20, and passes completely through the inner circumferential surface22of the attachment hole20in the radial direction.

A third drain passage37that drains the oil flowing from the second discharge passage33from the interior of the attachment hole20is formed in the pump housing30. The third drain passage37is located below the second discharge passage33.

(Functions of Composite Valve Apparatus)

The composite valve apparatus10includes a relief-valve mechanism11that is actuated by the pressure of the oil flowing through the first discharge passage32, and a thermo-valve mechanism12that is actuated by the heat of the oil flowing through the second discharge passage33.

With reference toFIG.2andFIG.3, the relief-valve mechanism11includes a first valve40that can reciprocate in the depthwise direction (the vertical direction) of the attachment hole20, a first spring51that applies force to the first valve40in the direction in which the first valve40becomes close to the bottom surface21of the attachment hole20, and a plug member24which supports the first spring51directly or indirectly via any member, and which closes the open end23(seeFIG.1) of the attachment hole20.

The first valve40includes a valve upper component60and a valve lower component70(a cylindrical body) which are fastened with each other. Note that although it is not illustrated in the figure, the valve upper component60and the valve lower component70may be an integrated singular component.

An outer circumferential surface63of the valve upper component60is slidable relative to the inner circumferential surface22of the attachment hole20. The valve upper component60is formed in a substantially cylindrical shape. More specifically, the valve upper component60includes an annular edge61that can be in contact with the bottom surface21of the attachment hole20, a pressure receiving surface62which is concaved from the annular edge61and which receives the pressure of the oil flowing through the first discharge passage32, and an annular fastening portion64which is provided at the opposite side to the pressure receiving surface62in the direction along an axial line Ax, and to which the valve lower component70can be fastened, and those are integrated with each other. The outer circumferential surface63and the fastening portion64may be separate components from each other.

The valve lower component70has a cylindrical large-diameter portion71. An outer circumferential surface72of the large-diameter portion71is slidable relative to the inner circumferential surface22of the attachment hole20. The inner circumferential surface of an upper end portion73(one end of the cylindrical body) of the large-diameter portion71and the outer circumferential surface of the fastening portion64are engaged with each other through a C-shape retainer ring41. That is, the valve lower component70is provided at the opposite side to the pressure receiving surface62in the direction along the axial line Ax. In other words, the valve lower component70is located between the valve upper component60of the first valve40and the plug member24. Note that although it is not illustrated in the figure, the thermo-valve mechanism12may be provided at the pressure-receiving-surface-62side of the valve upper component60.

The first spring51is a compression coil spring. An upper end portion51aof the first spring51is supported by or abuts an annular lower end surface74of the large-diameter portion71.

The plug member24is screwed in and fastened to the open end23of the attachment hole20. The plug member24supports or abuts a lower end portion51bof the first spring51.

(Opening and Closing Actions of Relief-Valve Mechanism)

FIG.4Aillustrates the relief-valve mechanism11in a closed state. In a state in which the pressure of the oil flowing through the first discharge passage32does not reach the predetermined pressure, the annular edge61of the first valve40is in contact with the bottom surface21of the attachment hole20. The outer circumferential surface63of the valve upper component60blocks off the first drain passage35. The outer circumferential surface72of the large-diameter portion71of the valve lower component70blocks off the second drain passage36. The large-diameter portion71is located so as to traverse the second discharge passage33. Note thatFIG.4Acan be regarded as a state immediately after the composite valve apparatus10is attached to the attachment hole20.

When the pressure of the oil flowing through the first discharge passage32increases, the first valve40moves downwardly against the pushing force from the first spring51.

FIG.4Billustrates the relief-valve mechanism in an open state. In a state in which the pressure of the oil flowing through the first discharge passage32reaches the predetermined pressure, the first discharge passage32, the first drain passage35and the second drain passage36are in communication with each other through the attachment hole20. The oil in the first discharge passage32flows in the first drain passage35and the second drain passage36, is returned to an unillustrated oil pan that reserves the oil and an unillustrated suction passage, and thus the pressure of the oil flowing through the first discharge passage32can be decreased.

When the pressure of the oil flowing through the first discharge passage32decreases, the first valve40moves upwardly by the pushing force of the first spring51, the first valve40blocks off the first drain passage35and the second drain passage36, and thus the relief-valve mechanism becomes a closed state illustrated inFIG.4A.

Note that the number of openings that allows the oil flowing from the first discharge passage32to bypass can be changed as appropriate. A state in which at least the first drain passage35is opened can be regarded as the open state of the relief-valve mechanism11.

With reference toFIG.2andFIG.3, the thermo-valve mechanism12includes a valve lower component70, a thermo actuator80retained in a large-diameter portion71of the valve lower component70, a second valve90fastened to a lower end portion80a(one end of the thermo actuator80) of the thermo actuator80, and a second spring52that applies force to the thermo actuator80in the direction in which the thermo actuator80becomes close to the valve upper component60.

The valve lower component70includes a cylindrical small-diameter portion76that extends from the lower inner circumferential edge of the cylindrical large-diameter portion71toward the plug member24, and a bottom portion77that closes the lower side of the small-diameter portion76. The large-diameter portion71, the small-diameter portion76, and the bottom portion77are integrated with each other as a singular component. The interior of the large-diameter portion71and that of the small-diameter portion76are in communication with each other.

The large-diameter portion71is provided with a pair of introducing holes75and75that are opened so as to introduce the oil in the interior of the large-diameter portion71. The respective introducing holes75and75are offset by 180 degrees relative to each other in the circumferential direction.

The small-diameter portion76is provided with a drain hole78that is opened so as to cause the oil flowing in the interior of the small-diameter portion76from the large-diameter portion71to discharge to the exterior of the valve lower component70.

The thermo actuator80has characteristics such that as the temperature of the oil flowing through the second discharge passage33increases, the entire length in the depthwise direction of the attachment hole20extends. More specifically, the thermo actuator80includes a wax81that expands by the heat of the oil, a casing82that retains therein the wax81, and a rod83which has a part embedded in the wax81, and which is pushed out and protrudes further from the casing82by the expansion of the wax81.

The upper end (the other end of the thermo actuator) of the rod83is supported by or abuts the internal side in the radial direction of the fastening portion64of the first valve40.

The second valve90includes a cylindrical main body portion91that has an outer circumferential surface91awhich is slidable relative to an inner circumferential surface76aof the small-diameter portion76, a lid portion92that blocks off the upper end of the main body portion91, and a fastening portion93which extends from the lid portion92toward the thermo actuator80, and which is fastened to the thermo actuator80, and those are integrated with each other as a singular component. The fastening portion93of the second valve90is fitted in a lower end portion80aof the thermo actuator80, and those are swaged with each other so as to be fastened to each other.

The second valve90is located inside the first spring51in the radial direction.

The first spring51is placed so as to surround the small-diameter portion76.

The second spring52is retained in the large-diameter portion71of the valve lower component70together with the thermo actuator80. The second spring52is a compression coil spring, and is placed so as to surround the casing82of the thermo actuator80.

An upper end portion52aof the second spring52is supported by or abuts a spring retaining portion84formed integrally with the outer circumferential surface of the casing82. A lower end portion52bof the second spring52is supported by or abuts an annular stepped surface70athat connects the inner circumferential surface of the large-diameter portion71and the inner circumferential surface76aof the small-diameter portion76with each other.

(Opening and Closing Actions of Thermo-Valve Mechanism)

FIG.5Aillustrates the thermo-valve mechanism12in an open state. In a state in which the temperature of the oil flowing through the second discharge passage33(seeFIG.3) does not reach the predetermined temperature, the main body portion91of the second valve90is located above the drain hole78.

The oil flowing in the interior of the large-diameter portion71from the introducing holes75and75of the large-diameter portion71passes through a hole92aof the lid portion92of the second valve90, flows in the interior of the main body portion91of the second valve90, and is drained from the drain hole78of the small-diameter portion76.

When the temperature of the oil increases, the heat of the oil is transferred to the wax81through the casing82of the thermo actuator80. When the wax81expands, the rod83protrudes upwardly relative to the casing82of the thermo-valve mechanism12against the pushing force by the second spring52. The upper end of the rod83is supported by or abuts the first valve40. Accordingly, the casing82moves downwardly relative to the valve upper component60of the first valve40. The second valve90fastened to the lower end portion80aof the thermo actuator80moves downwardly.

FIG.5Billustrates the thermo-valve mechanism12in a closed state. In a state in which the temperature of the oil flowing through the second discharge passage33(seeFIG.3) exceeds the predetermined temperature, the outer circumferential surface91aof the main body portion91of the second valve90blocks off the drain hole78. Accordingly, the oil flowing in the interior of the large-diameter portion71is not drained from the drain hole78.

When the temperature of the oil flowing through the second discharge passage33decreases, the casing82of the thermo actuator80moves upwardly by the force of the second spring52, the main body portion91of the second valve90is located above the drain hole78, and thus the thermo-valve mechanism12becomes an open state illustrated inFIG.5A.

Although the thermo-valve mechanism12of the composite valve apparatus10according to the first embodiment employs a structure that is closed when the temperature of the oil flowing through the second discharge passage33reaches the predetermined temperature, when the composite valve apparatus10is provided in another hydraulic circuit, a structure in which the position of the drain hole78is changed as appropriate so as to be opened when the temperature of the oil reaches the predetermined temperature.

(Opening and Closing Actions of Composite Valve Apparatus)

The relief-valve mechanism11illustrated inFIG.4AandFIG.4B, and the thermo-valve mechanism12illustrated inFIG.5AandFIG.5Bactuate independently from each other. That is, the composite valve apparatus10has four states that are a combination of the open and closed states of the relief-valve mechanism11and the open and closed states of the thermo-valve mechanism12.

FIG.6Aillustrates the composite valve apparatus10in which the relief-valve mechanism11is in a closed state, and the thermo-valve mechanism12is in an open state.

The first valve40blocks off the first drain passage35and the second drain hole36. The oil does not flow to the first drain passage35and the second drain hole36from the first discharge passage32. The drain hole78of the small-diameter portion76is opened. The oil drained from the drain hole78flows in the third drain passage37, and is returned to the oil pan that reserves the oil and the suction passage.

FIG.6Billustrates the composite valve apparatus10in which the relief-valve mechanism11is in an open state and the thermo-valve mechanism12is also in an open state.

The first discharge passage32, the first drain passage35and the second drain passage36are in communication with each other through the attachment hole20. The oil flowing through the first discharge passage32flows in the first drain passage35and in the second drain passage36through the interior of the attachment hole20. The drain hole78of the small-diameter portion76is open. The oil drained from the drain hole78flows in the third drain passage37, and is returned to the oil pan that reserves the oil and the suction passage.

Note that the introducing passage and the second discharge passage33are always in communication with each other through the interior of the first valve40regardless of the position of the first valve40.

FIG.7Aillustrates the composite valve apparatus10in which the relief-valve mechanism11is in a closed state and the thermo-valve mechanism12is also in a closed state.

The first valve40blocks off the first drain passage35and the second drain passage36. The second valve90blocks off the drain hole78of the small-diameter portion76.

FIG.7Billustrates the composite valve apparatus10in which the relief-valve mechanism11is in an open state and the thermo-valve mechanism12is in a closed state.

The first discharge passage32, the first drain passage35and the second drain passage36are in communication with each other through the attachment hole20. The oil flowing through the first discharge passage32flows in the first drain passage35and in the second drain passage36through the interior of the attachment hole20. The second valve90blocks off the drain hole78of the small-diameter portion76.

(Advantageous Effects of First Embodiment)

With reference toFIG.2andFIG.3, the composite valve apparatus10is attachable to the attachment hole20that has the open end23directed outwardly. The interior of the attachment hole20is in communication with the first discharge passage32and with the second discharge passage33.

The composite valve apparatus10includes the relief-valve mechanism11that becomes an open state (seeFIG.4B) when the pressure of the oil flowing through the first discharge passage32reaches the predetermined pressure. The relief-valve mechanism11includes the first valve40movable in the direction becoming apart from the bottom surface21of the attachment hole20along the depthwise direction of the attachment hole20by the force applied to the pressure receiving surface62that receives the pressure of the oil flowing through the first discharge passage32, the first spring51that applies the force to the first valve40in the direction in which the first valve40becomes close to the bottom surface21of the attachment hole20, and the plug member24which supports the first spring51and which closes the open end23of the attachment hole20.

The composite valve apparatus10includes the thermo-valve mechanism12that becomes a closed state (seeFIG.5B) when the temperature of the oil flowing through the second discharge passage33increases and reaches the predetermined temperature. The thermo-valve mechanism12includes the thermo actuator80that extends the entire length along the depthwise direction of the attachment hole20as the temperature of the oil increases, the second valve90fastened to the lower end of the thermo actuator80, and the valve lower component70that retains therein the thermo actuator80and the second valve90. The valve lower component70includes the introducing holes75and75that introduce the oil into the interior of the valve lower component70, the drain hole78which is opened or closed by the second valve90and which drains the oil introduced from the introducing holes75and75, and the bottom portion77that closes the lower end of the small-diameter portion76.

The first valve40of the relief-valve mechanism11and the second valve90of the thermo-valve mechanism12have respective axial lines Ax overlapping with each other. The upper end of the rod83of the thermo actuator80is supported by or abuts the first valve40. The upper end portion73of the valve lower component70is fastened to or integrated with the first valve40.

That is, the composite valve apparatus10has the thermo actuator80and valve lower component70of the thermo-valve mechanism12attached to the valve upper component60of the relief-valve mechanism11. In other words, the entire thermo-valve mechanism12is movable along the axial line Ax together with the valve upper component60. Although the composite valve apparatus10is a singular unit, it has two functions.

Since the composite valve apparatus10is a singular unit, the number of the attachment holes20to attach the composite valve apparatus10is sufficient by one. Hence, the number of the attachment holes20to be formed in the pump housing30can be reduced. The number of the plug members24that close the attachment hole20is also sufficient by one. Accordingly, the manufacturing costs can be suppressed.

Moreover, the space occupied by the attachment hole20in the pump housing30can be reduced, increasing the degree of freedom for designing a layout to place components in the pump housing30.

Note that when the valve upper component60and the valve lower component70are integrated with each other, the number of components can be reduced.

(Improvement of Degree of Freedom for Designing Pressure Receiving Surface of First Valve)

The valve lower component70and thermo actuator80of the thermo-valve mechanism12are located at the opposite side to the pressure receiving surface62of the valve upper component60of the relief-valve mechanism11. Hence, in comparison with a case in which the thermo-valve mechanism12is provided at the pressure-receiving-surface-62side, the degree of freedom for designing the pressure receiving surface62of the valve upper component60increases.

(Downsizing of Composite Valve Apparatus)

Since the outer circumferential surface72of the large-diameter portion71of the valve lower component70is slidable relative to the inner circumferential surface22of the attachment hole20, the large-diameter portion71of the valve lower component70can be regarded as a part of the first valve40. The valve lower component70forms the thermo-valve mechanism12, and also forms the relief-valve mechanism11. Since the valve lower component70is the structural component of both mechanisms, the number of components can be reduced.

Note that the valve lower component70is a member that retains therein the thermo actuator80. Accordingly, it can be regarded that the thermo actuator80is retained in the first valve40of the relief-valve mechanism11. Hence, regarding the dimension of the attachment hole20in the depthwise direction, the composite valve apparatus10can be downsized.

In addition, the first spring51of the relief-valve mechanism11is a compression coil spring. The second valve90of the thermo-valve mechanism12is located inwardly relative to the first spring51in the radial direction. That is, the first spring51and the second valve90overlap in the depthwise direction of the attachment hole20. Regarding the dimension of the attachment hole20in the depthwise direction, the composite valve apparatus10can be downsized.

The advantageous effects of the above-described first embodiment are also accomplished in a second embodiment to be described below. The same structural component as that of the first embodiment will be denoted by the same reference numeral as that of the first embodiment, and the duplicated description thereof will be omitted.

Second Embodiment

FIG.8Aillustrates a composite valve apparatus10A in which a relief-valve mechanism11A is in a closed state. With the annular edge61of the valve upper component60of a first valve40A being in contact with the bottom surface21of the attachment hole20, an upper end75Aa of an introducing hole75A of a valve lower component70A is located below an upper end34aof a wall surface34that defines a second discharge passage33A.

FIG.8Billustrates the composite valve apparatus10A in which the relief-valve mechanism11A is in an open state. When the first valve40is located at the lowermost position (i.e., when the small-diameter portion76of the valve lower component70A is in contact with the plug member24, or when the pressure of the oil flowing through the first discharge passage32increases to the maximum), a lower end75Ab of the introducing hole75A of the valve lower component70A is located above a lower end34bof the wall surface34that defines a second discharge passage33A.

According to the above-described structure, the flow passage area of the introducing hole75A of the thermo-valve mechanism12A is constant regardless of the position of the first valve40A of the relief-valve mechanism11A. Hence, the actuation of the relief-valve mechanism11A does not affect to the actuation of the thermo-valve mechanism A.

Note that as far as the actions and advantageous effects of the present disclosure can be accomplished, the present disclosure is not limited to the first and second embodiments.