PRIORITY DOCUMENTS

[0001] The present application claims priority from Australian Provisional Patent Application No.

2017903826 titled "HOIST CHECK VALVE IMPROVEMENTS" and filed on 20 September 2017, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to a check valve for a hydraulic cylinder performing a safety critical function. The invention is described in relation to a tipping truck or trailer, but it is not so limited in application, with potential applications including all of those in which a hydraulic cylinder is used to lift a load and maintain it in an elevated position.

BACKGROUND

[0003] A hoist check valve functions to lock a hydraulic cylinder (the hoist) in position, and keep the hoist in this position even if a pressure loss event occurs. This function is safety critical in machinery such as tipping trucks and trailers, which comprise a bed which is tilted by the hoist cylinder, as the hoist check valve prevents uncommanded drop of a raised (tilted) bed.

[0004] A typical hoist check valve of the prior art comprises a valve body and a commercial off the shelf pneumatically actuated cartridge valve secured with respect to the valve body.

[0005] The operators of tipping trucks and trailers operate in a highly competitive environment, and so they are constantly seeking cheaper and more reliable components.

[0006] It is against this background and the problems and difficulties associated therewith that the present invention has been developed.

[0007] Certain objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed. SUMMARY

[0008] According to a first aspect, there is provided a valve assembly comprising a body, the body housing both a pneumatic valve member and a hydraulic valve member, which are so operatively connected that the pneumatic valve member actuates the hydraulic valve member.

[0009] According to a second aspect, there is provided a valve assembly comprising a body, wherein the body comprises a first port, a second port, a fluid passageway extending between the first port and the second port, a bore, and a partition separating the fluid passageway from the bore, the valve assembly further comprising a piston comprising a head slidably disposed within the bore to reciprocate therein, and a spool extending from the head, and through the partition into the fluid passageway, and movable between an open position and a closed position with respect to the fluid passageway, and wherein the piston and spool are biased via a biasing means toward the closed position.

[0010] In one form, the valve assembly further comprises a poppet positioned within the fluid passageway and biased against a valve seat by a biasing means, and wherein the spool is slidably disposed within the poppet to reciprocate therein and move between its open and closed positions.

[001 1] In one form, the valve body comprises a pair of ends and at least one side, and the inlet port is at an end of the body, and the outlet port is in a side of the body.

[0012] In one form, the poppet comprises a generally cylindrical body comprising a pair of ends and a side, and further comprising a first port in an end of the poppet body, and a second port in the side of the poppet body, and a fluid passageway extending between the first port and the second port, which the spool will selectively open and close.

[0013] In one form, the poppet comprises a plurality of the second ports.

[0014] In one form, a central axis of each of the piston, the bore, the spool, the poppet and the inlet port are all aligned.

[0015] In one form, the biasing means comprises a spring.

[0016] In one form, the valve body comprises at least one gallery for directing compressed air to the bore to drive against the head of the piston.

[0017] In one form, the valve body is machined. [0018] In one form, in an alternative, the valve body may be any one of cast, moulded or 3D printed. [0019] In one form, the valve body is steel.

[0020] In one form, in an alternative the valve body is plastic, ceramic or a composite material.

[0021 ] According to a further aspect, there is provided a valve assembly comprising a body, the body housing both a pneumatic valve member comprising a piston and a hydraulic valve member comprising a spool, wherein the piston and the spool are integrally formed so that the pneumatic valve member actuates the hydraulic valve member.

[0022] In one form, the body is formed as a single, integral piece.

[0023] In one form, in an alternative, the body is formed from at least two pieces which are joined together.

[0024] For ease of description, a valve assembly is described below in its usual assembled position as shown in the accompanying drawings, and terms such as front, rear, upper, lower, horizontal, longitudinal etc., may be used with reference to this usual position. However, the valve assembly may be manufactured, transported, sold, or used in orientations other than that described and shown here.

[0025] The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured.

BRIEF DESCRIPTION OF DRAWINGS

[0026] Embodiments of the present invention will be discussed with reference to the accompanying drawings wherein:

[0027] Figures 1 and 2 are isometric views of a valve assembly when viewed from opposing ends; [0028] Figures 3 and 4 are opposing side views of the valve assembly; [0029] Figures 5 and 6 are opposing plan views of the valve assembly; [0030] Figures 7 and 8 are opposing end views of the valve assembly; [0031] Figure 9 is an exploded view of the valve assembly;

[0032] Figure 10 is a cross-sectional view of the valve assembly in a rest state;

[0033] Figure 11 is a cross-sectional view of the valve assembly configured to permit flow in a first direction;

[0034] Figure 12 is a cross-sectional view of the valve assembly configured to permit flow in a second, opposing direction;

[0035] Figure 13 is an isometric view of a valve assembly according to a further embodiment; and [0036] Figure 14 is an exploded view of the valve assembly of Figure 13.

[0037] In the following description, like reference characters designate like or corresponding parts throughout the figures.

DESCRIPTION OF EMBODIMENTS

[0038] Referring now to Figure 1, where there is illustrated a valve assembly 1 comprising a body 2 comprised of a single, integral piece of machined steel in this case, although it could take other forms, be manufactured by other suitable means, and/or employ other suitable materials.

[0039] The body 2 comprises a block shaped portion 4, an adjoined cylindrical shaped portion 6, and a pair of ends.

[0040] The block shaped portion 4 of the body comprises a first port 10, a second port 12, and a fluid passageway 14 extending between the first port 10 and the second port 12. The first port 10 is in an end of the block shaped portion 4 of the body, and the second port is in a side of the block shaped portion 4. In this embodiment, the first port 10 is fitted with a fitting 90.

[0041] The cylindrical shaped portion 6 of the body comprises a bore 20 extending therethrough, and a partition 16 which separates the fluid passageway 14 from a first end of the bore 20. A second end of the bore 20 comprises an end cap 80 which closes the bore 20, but is removable to provide access to the bore 20.

[0042] The valve assembly 1 further comprises a piston 30 comprising a head 32 which is slidably disposed within the bore 20 to reciprocate therein, and a spool 34 extending from the head 32 and through a hole and seal 35 therefor in the partition 16, into the fluid passageway 14. The piston 30 further comprises a guide rod portion 33 which is slidably disposed in a guide bore 88 in a guide collar 86 of the end cap 80, to guide movement of the piston 30. The piston 30 is machined from a single, integral piece of steel in this case, although it could take other forms, be manufactured by other suitable means, and/or employ other suitable materials.

[0043] The valve assembly 1 further comprises a poppet 50 positioned within the fluid passageway 14 and biased against a floating valve seat 70 by a biasing means comprising a spring 60. The valve seat 70 is floating so as to accommodate any misalignment of the poppet 50 as this engages the valve seat 70.

[0044] The poppet 50 comprises a generally cylindrical body 52 comprising a pair of ends and a side, and further comprising a port 54 in an end of the poppet body 52, and a plurality of ports 56 equispaced around the side of the poppet body 52, and a fluid passageway extending between the end port 54 and the side ports 56, which the spool 34 will selectively open and close.

[0045] The fluid passageway in the poppet 50 comprises a bore in which the spool 34 is slidably disposed to reciprocate therein and move between an open position and a closed position with respect to the side ports 56 in the poppet 50. The piston 30 and spool 34 together are biased towards the closed position by a biasing means comprising springs 40 and 42 which are arranged in parallel, with spring 40 inserted inside of spring 42.

[0046] A central axis of each of the piston, the bore, the spool, the poppet and the inlet port are all aligned.

[0047] The end cap 80 comprises a connection port 82 for a pressurised air supply, and the body 2 comprises a pair of galleries 84 connecting the connection port 82 to the bore 20 so that the air may drive against the head 32 of the piston 30.

[0048] Referring now to Figure 10, where the valve assembly is illustrated in a 'rest state'. In the rest state the springs 40, 42 and 60 bias the piston 30 and the poppet 50 respectively into a home position. The home position for the head 32 of the piston 30 is hard against the partition 16, and the home position for poppet 50 is seated against the floating seat 70. The home position for the spool 34 of the piston 30 sees it closing the side ports 56 of the poppet 50. In the rest state, no hydraulic fluid is permitted to flow between the first port 10 and the second port 12.

[0049] With reference to Figure 12, it can be seen how in use, to extend a hoist cylinder and raise (tilt) a bed, a hydraulic fluid is supplied under pressure (from a pump and via a directional control valve) to the first port 10, until fluid pressure is sufficient that the bias of the spring 60 is overcome so that the poppet 50 is driven clear of the floating valve seat 70, thereby permitting fluid flow from the first port 10 to the second port 12.

[0050] When the hoist cylinder is extended, the hydraulic fluid pressure drops, and the spring 60 will drive the poppet 50 against the floating valve seat 70 thereby returning the valve assembly 1 to its rest state, as illustrated in Figure 10, and preventing uncommanded retraction of the hoist cylinder.

[0051 ] With reference to Figure 1 1 , it can be seen how in order to retract the hoist cylinder and lower the bed, a supply of pressurised air is supplied to the bore 20 via the galleries 84 to drive the head 32 and the spool 34 away from their respective home positions against the bias of the springs 40 and 42, so that the side ports 56 in the poppet 50 are unobstructed, thereby permitting hydraulic fluid flow from the second port 12, through the poppet 50 and to the first port 10.

[0052] A manual override 100 is provided so the fluid may be released and the bed lowered in the event of any failure.

[0053] Referring now to Figures 13 and 14, where there is illustrated a valve assembly 1 a. Those parts of the valve assembly la which are identical (or near- identical) to corresponding parts shown in the valve assembly 1 of Figures 1 through 12, will be denoted by the same reference numerals and will not be described again in detail.

[0054] The body 2 of valve assembly la comprises a block shaped portion 4 and an adjoined cylindrical shaped portion 6 as before, but in this case these portions 4 and 6 are separately formed, and then joined to form the body 2 via a connector 110.

[0055] In the case of this embodiment, the cylindrical body portion 6 comprises a male threaded collar, and the connector 1 10 comprises a female threaded collar 112 (which further comprises external flats for a spanner or wrench) for receiving the male threaded collar 112 of the cylindrical body portion 6, and a spigot portion 114 comprising a male threaded portion for insertion into the block shaped portion 4. The spigot portion 114 comprises a passageway for receiving the poppet 50, and ports which are aligned with the ports 10 and 12 in the block shaped portion 4, so that the valve assembly la may function in the same way as valve assembly 1.

[0056] And so, the valve assembly according to the present disclosure comprises a body housing both a pneumatic valve member and a hydraulic valve member which are so operatively connected that the pneumatic valve member actuates the hydraulic valve member. The integral, unitary nature of the piston 30 makes for a simple and reliable design, which the applicant anticipates can be produced at a lower cost than a typical hoist check valve of the prior art.

[0057] Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0058] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0059] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention as set forth and defined by the following claims.