AU2014268204B2 - A Hand Pump Apparatus - Google Patents

Abstract

A hand pump apparatus for noxious or corrosive materials, the hand pump including a tubular housing with a bore therethrough, a housing outlet at a forward end of the tubular housing, a shaft associated with a piston head adapted for reciprocal movement relative to the housing, the shaft having a bore therethrough with an inlet and an outlet, a first valve assembly associated with the bore of the housing, a second valve assembly associated with the bore of the shaft with a charging chamber defined between the first and second valve assemblies, such that movement of the shaft rearwardly relative to the housing forces material in the charging chamber out through the housing outlet and movement of the shaft forwardly relative to the housing charges the charging chamber with material through the bore in the shaft wherein the shaft and the housing are concentric. Cl L) r1> r>1 V06 C7) Arl

Description

A HAND PUMP APPARATUS TECHNICAL FIELD

[0001] The present invention relates generally to hand pumps and particularly to a hand pump for application of noxious liquids to plants and the like.

BACKGROUND ART

[0002] There are a variety of manually actuated pumps commercially available, many of which operate around a pistol grip arrangement having a trigger wherein depression of the trigger forces ejection of the material contained in a reservoir and release of the trigger causes suction which draws material into the reservoir from a larger container.

[0003] However, a number of issues exist with the pistol grip hand pumps in that the number configuration of moving parts often results in leaks which either involve resolution by replacement or by maintenance of the seals in the hand pumps.

[0004] This leads to higher costs on new pumps and/or service keeps and also loss of productivity due to downtime.

[0005] It will be clearly understood that, if a prior art publication referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

SUMMARY OF INVENTION

[0006] The present invention is directed to a hand pump apparatus, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

[0007] With the foregoing in view, the present invention in one form, resides broadly in a hand pump apparatus for noxious or corrosive materials, the hand pump including a tubular housing with a bore therethrough, a housing outlet at a forward end of the tubular housing, a shaft associated with a piston head adapted for reciprocal movement relative to the housing, the shaft having a bore therethrough with an inlet and an outlet, a first valve assembly associated with the bore of the housing, a second valve assembly associated with the bore of the shaft with a charging chamber defined between the first and second valve assemblies, such that movement of the shaft rearwardly relative to the housing forces material in the charging chamber out through the housing outlet and movement of the shaft forwardly relative to the housing charges the charging chamber with material through the bore in the shaft wherein the shaft and the housing are concentric.

[0008] The hand pump of the present invention is particularly for use with noxious or dangerous materials. The hand pump is preferably for use with fluids or liquids, but this does not need to be the case and the invention is not limited in a way. The hand pump is typically used in connection with a material supply conduit which is associated with a material container containing bulk material to be dispensed using the hand pump.

[0009] Preferably, all components of the hand pump are manufactured from metal with no non-metal parts except for the seals and the preferred protection boot. The preferred materials of construction are high-grade stainless steel, but other components may be manufactured from bronze or brass. In particular, the piston head/valve seat may be manufactured from bronze or brass.

[0010] The hand pump of the present invention will typically require two-handed operation with one hand moving the shaft whilst the other hand braces the housing against movement. Preferably, the action is reciprocal and the shaft of the hand pump is biased into the charged condition rather than into the discharge condition.

[0011] As will be described in more detail below, the components of the hand pump will preferably be coaxial with one another and for the most part also concentric. The respective bores of the housing and the shaft are preferably coaxial.

[0012] The preferred hand pump will also allow adjustment of the size of the charge in order to allow the user control metering of the material expelled or delivered. This will typically be accomplished by providing different spacers onto the shaft in order to change the length of the stroke of the shaft relative to the housing. These spacers will normally be manufactured from a suitable material such as acetyl nylon.

[0013] The hand pump of the present invention includes a tubular housing with a bore therethrough. This bore can be thought of as a main bore as it will in large part defined the charging chamber as well as allow movement of the piston head into the housing.

[0014] The housing is preferably circular in cross section but this is not essential. The housing defines the charging chamber therein and also provides a guide for the reciprocal action of the shaft/piston head. The preferred housing is a multipart housing with the various components of the housing removably attached together for use but capable of disconnection for maintenance and/or servicing for example.

[0015] The preferred housing includes three components, namely a head component, a body component and a tail component.

[0016] The tail component will typically include a housing inlet. The housing inlet will normally be provided with an attachment configuration provided to attach different additional components as required. The preferred attachment configuration is by provision of an internally threaded portion however any configuration can be provided.

[0017] The tail component can have any shape externally. Internally however, the tail component is normally provided with a first bore portion which is an entry bore to the housing and preferably to the charging chamber which is preferably also located within the tail portion.

[0018] A radially extending shoulder is typically provided at a forward end of the first bore portion. A larger diameter entry bore is preferably provided between the first bore portion and the charging chamber.

[0019] One or more tapered bore portions may be provided in the first bore portion in order to reduce fluid pressure losses from the main bore portion into the charging chamber.

[0020] Preferably, the first bore portion is coaxial with the charging chamber, the bore in the body component and also with the bore in the shaft.

[0021] Located toward the inlet end of the of the first bore portion bore (and preferably at least partially between the tail portion and an entry fitting) is the first valve assembly. The first valve assembly typically includes a valve member which is movable relative to a valve seat between an open and a sealed condition. Typically, the valve member is biased into the sealed condition using a biasing member, typically a spring or similar and the biasing member is braced against a locating member or part of the first bore portion in order to limit the movement of the biasing member. Typically, the locating member or part of the first bore portion may be provided within the first bore portion and adjacent the valve seat. The locating member or part of the first bore portion can be as simple as a circlip or similar which fits into a circumferential groove and against which an end of the biasing member is braced.

[0022] The valve member can be any shape but preferably, is at least partially spheroidal or frustoconical in shape as the shapes provide enhanced sealing characteristics without the need for additional sealing members. The simplest valve member is a spherical ball valve member.

[0023] The valve seat is typically shaped to correspond to the shape of the valve member or vice versa. As mentioned above, the valve member is preferably biased into the sealed condition and requires a force to displace the valve member from the seat to move the valve member to the open condition allowing material to flow past the valve member. This occurs typically when the shaft is released after discharge or emptying of the charging chamber upon which the main biasing means will force the shaft forwardly again which in turn creates a lower pressure volume in the charging chamber which will draw the material into the charging chamber against the valve member which displaces the valve member from the seat.

[0024] During retraction of the shaft, the pressure exerted on the material in the charging chamber will assist with the sealing of the first valve assembly preventing backflow and also preventing material being drawn into the charging chamber until the shaft is released.

[0025] The body component is preferably quite simple, and substantially tubular. The body component will preferably receive a portion of the tail portion within.

[0026] The body component preferably has an attachment configuration provided at both ends, one attachment configuration to attach to the head component and the other to seat the tail component. Preferably, the head component attachment configuration is an externally threaded portion. The tail attaching component is preferably a circumferential seat against which a portion of the tail component can be seated and then held in place by the attachment of the head component.

[0027] Preferably, the bore portion through the body closely receives the tail component and particularly, the part of the tail component which defines the charging chamber.

[0028] The tail component is also preferably provided with an attachment configuration to attach to the body component. Again, the preferred attachment configuration is a circumferential shoulder to abut and be seated against the circumferential should of the body portion.

[0029] Externally, the tail component will typically be smaller than the body component and the head component larger than the body or at least substantially the same dimension. This provides the housing with a gripping portion about the body component between the head component and tail component.

[0030] The head component is also preferably provided with a recess or depression, typically circumferentially in order to allow the protection boot to be properly seated and attached to the head component. Generally, a shoulder is provided on each side of the recess in order to provide an abutment portion. Typically, a circumferential clamping device is used to clamp the protection boot in the recess or depression between the shoulders.

[0031] A seating portion is also provided on the head component for seating a shaft biasing member relative thereto. Typically, the biasing member will be a spring or similar used to bias the shaft into the charged condition or to a condition which creates a charging chamber with material therein. Normally, the seating portion is a circumferential extension provided adjacent the bore portion of the head component and concentrically thereabout.

[0032] Typically, the preferred biasing spring is received about the seat. Deformation of the spring may be required in order to properly seat the spring on the seating portion. Further, the spring will typically be retained thereon by a friction fit. Preferably, the shaft biasing spring surrounds the shaft inside the protection boot and the opposite end of the shaft biasing spring is mounted to the shaft.

[0033] The tail component of the housing will preferably be tubular with a circumferential shoulder partway along the tail portion to provide an abutment with the body portion of the housing. The tail portion will normally have an enlarged portion to be partially received within the body portion of the housing such that the charging chamber is defined within the enlarged portion of the tail portion which is surrounded by the body portion. A smaller portion of the tail portion will preferably extend out of the body portion and attach a supply fixture to supply the material to the hand pump. The first valve assembly is preferably located between the smaller portion of the tail portion of the housing and the supply fixture and within the first bore portion.

[0034] The hand pump of the present invention includes a shaft associated with a piston head adapted for reciprocal movement relative to the housing, the shaft having a bore therethrough with an inlet and an outlet. Generally the inlet to the bore in the shaft will communicate with the charging chamber of the housing such that material exiting the charging chamber does so via the bore in the shaft.

[0035] The shaft and piston head is preferably provided in a two-part assembly with a unitary shaft and a separate but attachable piston head. The attachment of the piston head to the shaft is typically a threaded attachment. Normally, the inlet to the bore through the shaft will be provided through the piston head.

[0036] Typically, the shaft is movable such that the piston head reciprocates within the bore in the housing to define a charging chamber and then, when forced, to reduce the volume of the charging chamber defined in order to expel material from the charging chamber and the hand pump.

[0037] The piston head of the preferred embodiment is preferably manufactured from bronze or brass. A bore portion is typically provided through the piston head. A narrowed, neck portion is typically provided in the piston head in order to define a part of the valve chamber for the second valve assembly with the remainder of the valve chamber for the second valve assembly provided on or in a rear end of the shaft.

[0038] Typically, the piston head is externally shaped to allow attachment or securing of the piston head to the shaft using a tool, typically a spanner or similar.

[0039] A circumferential recess or seat is normally provided externally on the piston head to allow seating of a sealing member in order to form a better seal against the walls of the bore of the housing. Normally, the sealing member is an O-ring or similar.

[0040] The shaft is typically elongate and generally cylindrical. A bore is typically provided through the shaft. The bore is normally continuous and of constant dimension except for the part of the valve chamber for the second valve assembly provided on or in the end of the shaft.

[0041] The shaft is preferably sized to allow movement of the shaft and/or piston head into the bore provided in the tail or body component of the housing.

[0042] Preferably, a rearward end of the shaft is provided with a valve seat in order to seat a valve member of the second valve assembly.

[0043] The second valve assembly typically includes a valve member which is movable relative to a valve seat between an open and a sealed condition. Typically, the valve member is biased into the sealed condition using a biasing member, typically a spring or similar and the biasing member is braced against periphery of the valve chamber provided in the piston head in order to limit the movement of the biasing member.

[0044] The valve member can be any shape but preferably, is at least partially spheroidal or frustoconical in shape as these shapes provide enhanced sealing characteristics without or at least minimising the need for additional sealing members. The simplest valve member is a spherical ball valve member.

[0045] The valve seat is typically shaped to correspond to the shape of the valve member or vice versa. As mentioned above, the valve member is preferably biased into the sealed condition and requires a force to displace the valve member from the seat to move the valve member to the open condition allowing material to flow past the valve member. This occurs typically when the shaft is moved rearwardly under manual force against the biasing force of the shaft biasing member. This action forces the material in the charging chamber against the valve member which displaces the valve member from the seat.

[0046] Preferably, an enlarged collar portion or seat is provided in order to mount the other end of the shaft biasing spring to the shaft. Typically, a shoulder is provided for abutment of the spring. The shoulder is normally circumferential. The shaft biasing spring is normally received about the seat and deformation of the spring may be required in order to mount the spring properly. The spring is typically maintained on the seat through a friction fit.

[0047] There is also preferably a recess or depression formed by providing an enlarged annular portion spaced from the collar portion or seat. The recess or depression is typically circumferential and preferably allows proper seating and attachment of the protection boot to the shaft. A clamping device is normally used to clamp the boot to the shaft.

[0048] The protection boot is normally a resilient boot provided to enclose the moving parts of the hand pump in order to prevent dust and other detritus from invading the mechanism. The protection boot may contain a lubricant.

[0049] Typically, an attachment configuration is provided on the shaft and opposite the piston head in order to attach an outlet head to the shaft such that material provided through the shaft can be dispersed or directed as desired.

[0050] In use, the hand pump is assembled and connected to a supply conduit normally a flexible tube or pipe which is in turn connected to a material source. The shaft is then forced rearwardly and released to vent any air in the charging chamber and upon release, will act to open the first valve assembly and draw material into the charging chamber. The material cannot flow forwardly from the charging chamber because of the second valve assembly which is biased into the closed condition. Once the charging chamber is charged with material, depression of the shaft rearwardly, will force the material in the charging chamber forwardly from the hand pump and releasing the manual discharge force, will restart the charging cycle. In this manner, a measured charge of material is dispensed as required with recharging taking place after each discharge.

[0051] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

[0052] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS

[0053] Various embodiments of the invention will be described with reference to the following drawings, in which: [0054] Figure 1 is an axonometric view of the hand pump apparatus according to a particularly preferred embodiment of the present invention with the preferred rubber boot removed to show the inner workings.

[0055] Figure 2 is an axonometric view of the hand pump apparatus according to Figure 1 with the shaft removed from the housing.

[0056] Figure 3 is a detail view of Figure 2.

[0057] Figure 4 is an isometric view from the rear or supply end of the housing illustrated in Figures 2 and 3.

[0058] Figure 5 is an isometric view from the rear end of the shaft illustrated in Figures 2 and 3.

[0059] Figure 6 is an isometric view from the forward or outlet end of the shaft illustrated in Figure 5.

[0060] Figure 7 is a detailed view of the inlet or supply end of the housing tail according to a particularly preferred embodiment of the present invention.

[0061] Figure 8 is a detailed view of the piston head according to a particularly preferred embodiment of the present invention.

[0062] Figure 9 is a top view of the hand pump apparatus illustrated in Figure 1 in the charged condition.

[0063] Figure 10 is a top view of the hand pump apparatus illustrated in Figure 1 in the discharge condition.

[0064] Figure 11 is a cross sectional view of an alternative embodiment of the present invention showing the location and operation of the valves in a preferred embodiment.

DESCRIPTION OF EMBODIMENTS

[0065] According to a particularly preferred embodiment of the present invention, a hand pump apparatus is provided.

[0066] The hand pump apparatus 10 illustrated in the accompanying Figures includes a tubular housing 11 (Figure 4) with a bore 12 therethrough, a housing outlet 13 at a forward end of the tubular housing 11, and a shaft 14 (Figure 5) associated with a piston head 15 adapted for reciprocal movement relative to the housing 11. The shaft 14 has a bore 16 therethrough with an inlet and an outlet. A first valve assembly is associated with the bore 12 of the housing 11 and a second valve assembly is associated with the bore 16 of the shaft 14 with a charging chamber defined between the first and second valve assemblies. In use, movement of the shaft 14 rearwardly relative to the housing 11 forces material in the charging chamber out through the bore 16 of the shaft 14 and movement of the shaft 14 forwardly relative to the housing 11 charges the charging chamber with material through the inlet 50 in the housing. As illustrated, the shaft 14 and the housing 11 are coaxial and concentric.

[0067] Preferably, all components of the hand pump are manufactured from metal with no non-metal parts except for the seals and the protection boot (removed for clarity). The preferred materials of construction are high-grade stainless steel, but other components may be manufactured from bronze or brass such as the piston head/valve seat.

[0068] The hand pump of the preferred embodiment requires two-handed operation as illustrated in Figures 9 and 10, with one hand moving the shaft 14 whilst the other hand braces the housing 11 against movement. The action is reciprocal and the shaft 14 of the hand pump 10 is biased into the charged condition (Figure 9) rather than into the discharge condition (Figure 10) through provision of a main biasing spring 17.

[0069] The components of the hand pump 10 of the illustrated embodiment are coaxial with one another and for the most part, also concentric.

[0070] The hand pump of the present invention is particularly for use with noxious or dangerous materials. The hand pump is preferably for use with fluids or liquids, but this does not need to be the case and the invention is not limited in a way. The hand pump is typically used in connection with a material supply conduit which is associated with a material container containing bulk material to be dispensed using the hand pump.

[0071] Preferably, all components of the hand pump are manufactured from metal with no non-metal parts except for the seals and the preferred protection boot. The preferred materials of construction are high-grade stainless steel, but other components may be manufactured from bronze or brass. In particular, the piston head/valve seat may be manufactured from bronze or brass. Alternatively, the body may be manufactured of a plastic material such as acetyl.

[0072] The hand pump of the present invention will typically require two-handed operation with one hand moving the shaft whilst the other hand braces the housing against movement as illustrated in Figures 9 and 10.

[0073] As will be described in more detail below, the components of the hand pump will preferably be coaxial with one another and for the most part also concentric. The respective bores of the housing and the shaft are preferably coaxial.

[0074] The commercial embodiment of the hand pump will also typically allow adjustment of the size of the charge in order to allow the user control metering of the material expelled or delivered. This will typically be accomplished by providing different spacers onto the shaft in order to change the length of the stroke of the shaft relative to the housing. These spacers will normally be manufactured from a suitable material such as acetyl nylon. Alternatively, adjustment of the size of the charge may be accomplished by providing different interchangeable tail portions of the housing with smaller or larger charging chambers.

[0075] The hand pump of the present invention includes a tubular housing 11 with a bore therethrough. This bore can be thought of as a main bore as it will in large part define the charging chamber as well as allow movement of the piston head into the housing.

[0076] The housing is preferably circular in cross section but this is not essential. The housing defines the charging chamber 42 therein and also provides a guide for the reciprocal action of the shaft 14/piston head 15. The preferred housing is a multipart housing with the various components of the housing removably attached together for use but capable of disconnection for maintenance and/or servicing for example.

[0077] The preferred housing includes three components, namely a head component 18, a body component 19 and a tail component 20.

[0078] As illustrated, the tail component 20 include a housing inlet 50 which will normally be connected to a supply fixture such as that illustrated in Figure 11. The illustrated housing inlet 50 is internally threaded to allow connection.

[0079] Internally however, the tail component 20 is normally provided with a transition bore 22 which is an entry to the housing and preferably to the charging chamber 42 which is preferably also located within the tail portion 20 as illustrated in Figure 11.

[0080] A radially extending shoulder 45 is typically provided at a forward end of the transition bore 11. A larger diameter transition bore 46 is provided between the first bore portion 47 and the charging chamber 42.

[0081] Preferably, the first bore portion 47 is coaxial with the charging chamber 42, and also with the bore in the shaft.

[0082] Located toward the inlet end of the of the first bore portion 47 (and preferably at least partially between the transition bore 22 and a supply fixture 44) is the first valve assembly 40.

[0083] The preferred form of first valve assembly which is best illustrated in Figure 11, includes a valve member 51 which is movable relative to a valve seat 23 between an open and a sealed condition. Typically, the valve member is biased into the sealed condition using a biasing spring 52 and the biasing spring 52 is braced against a part of the first bore portion 47 in order to limit the movement of the biasing spring 52.

[0084] The valve member 51 can be any shape but preferably, is at least partially spheroidal as illustrated in Figure 11 to provide enhanced sealing characteristics without the need for additional sealing members.

[0085] The valve seat 23 is provided on the end of the supply fixture 44 and is shaped to correspond to the shape of the valve member. As mentioned above, the valve member 51 is biased into the sealed condition and requires a force to displace the valve member 51 from the valve seat 23 to move the valve member 51 to the open condition allowing material to flow past the valve member 51. This occurs when the shaft 14 is released after discharge or emptying of the charging chamber 42 upon which the main biasing spring 17 forces the shaft 14 forwardly again which in turn creates a lower pressure in the charging chamber 42 which draws the material into the charging chamber 42 against the valve member 51 which displaces the valve member 51 from the valve seat 23.

[0086] During retraction of the shaft 14 during discharge, the pressure exerted on the material in the charging chamber 42 assists with the sealing of the first valve assembly 40 preventing backflow and also preventing material being drawn into the charging chamber 42 until the shaft 14 is released.

[0087] The body 19 of the housing 11 is preferably quite simple, and substantially tubular. As illustrated in Figure 11, the body 19 will receive a portion of the tail portion 20 within.

[0088] The body 19 preferably has an attachment configuration provided at both ends, one attachment configuration being an externally threaded portion 53 to attach to the head component 18 and the other to seat the tail component 20. The tail attaching configuration is preferably a circumferential seat 54 against which a shoulder 45 of the tail component 20 can be seated and then held in place by the attachment of the head component 18 to the body 19.

[0089] Preferably, the bore portion through the body 19 closely receives the tail component 20 and particularly, the part 55 of the tail component 20 which defines the charging chamber 42.

[0090] Externally, the tail component 20 is usually smaller than the body component 19 and the head component 18 is larger than the body 19 or at least substantially the same dimension. This provides the housing 11 with a gripping portion 56 about the body 19 between the head component 18 and tail component 20.

[0091] The head component 18 is provided with a recess 24, typically circumferentially in order to allow the protection boot (not illustrated) to be properly seated and attached to the head component 18. Generally, a shoulder is provided on each side of the recess in order to provide an abutment portion. Typically, a circumferential clamping device is used to clamp the protection boot in the recess 24 between the shoulders.

[0092] A seat 25 is also provided on the head component 18 for seating a shaft biasing member which in the illustrated embodiment is a main spring 17 relative thereto to bias the shaft 14 into the charged condition or to a condition which creates a charging chamber 42 with material therein. Normally, the seat 25 is a circumferential extension provided adjacent the bore portion of the head component and concentrically thereabout.

[0093] As illustrated, the main spring 17 is received about the seat 25. Deformation of the spring 17 may be required in order to properly seat the spring 17 on the seat 25. Further, the spring 17 is retained thereon by a friction fit. Preferably, the main spring 17 surrounds the shaft 14 inside the protection boot and the opposite end of the main spring 17 is mounted to the shaft 14.

[0094] The tail component 20 of the housing 11 is tubular with an external circumferential shoulder 48 partway along the tail 20 to provide an abutment with the body 19 of the housing 11 as illustrated in Figure 11. The tail 20 will normally have an enlarged part 55 to be partially received within the body 19 of the housing 11 such that the charging chamber 42 is defined within the enlarged part 55 of the tail portion 20 which is surrounded by the body 19. A smaller portion of the tail portion will preferably extend out of the body portion and attach a supply fixture to supply the material to the hand pump. As illustrated in Figure 11, the first valve assembly 40 is located between the smaller portion of the tail portion of the housing and the supply fixture and within the first bore portion.

[0095] The hand pump of the present invention includes a shaft 14 associated with a piston head 15 adapted for reciprocal movement relative to the housing 11, the shaft 14 having a bore 16 therethrough with an inlet through the piston head 15 and an outlet 43 at a forward end. Generally the inlet to the bore 16 in the shaft 14 communicates with the charging chamber 42 of the housing 11 such that material exiting the charging chamber 42 does so via the bore 16 in the shaft 14.

[0096] The shaft 14 and piston head 15 are preferably provided in a two-part assembly with a unitary shaft and a separate but attachable piston head. The attachment of the piston head 15 to the shaft 14 in the illustrated embodiment is a threaded attachment.

[0097] The shaft 14 is movable such that the piston head 15 reciprocates within the bore in the housing 11 to define a charging chamber 42 and then, when forced, to reduce the volume of the charging chamber 42 defined in order to expel material from the charging chamber 42 and the hand pump.

[0098] The piston head 15 is usually manufactured from bronze or brass. As illustrated in Figure 5 in particular bore portion 49 is provided through the piston head 15. As illustrated in Figure 11, a narrowed, neck portion 57 is provided in the piston head in order to define a part of the valve chamber for the second valve assembly 41 with the remainder of the valve chamber for the second valve assembly 41 provided on or in a rear end of the shaft 14.

[0099] The illustrated piston head 15 is externally shaped with a pair of lands 26 to allow attachment or securing of the piston head 15 to the shaft using a tool, typically a spanner or similar.

[00100] A circumferential seat 27 is normally provided externally on the piston head 15 to allow seating of a sealing member in order to form a better seal against the walls of the bore of the housing. Normally, the sealing member is an O-ring 59 or similar.

[00101] The shaft 14 is typically elongate and generally cylindrical. A bore 16 is typically provided through the shaft 14. The bore 16 is normally continuous and of constant dimension except for the part of the valve chamber for the second valve assembly provided on or in the end of the shaft 14. Also, an optional exit port 58 may be provided in the shaft 14 in communication with the bore 16 which can be closed off with a plug if not used.

[00102] The shaft 14 is preferably sized to allow movement of the shaft 14 and/or piston head 15 into the charging chamber 42 provided in the tail component 20 of the housing.

[00103] As illustrated in Figure 11, a rearward end of the shaft 14 is provided with a valve seat 28 in order to seat a valve member 60 of the second valve assembly 41.

[00104] The second valve assembly 41 includes a valve member 60 which is movable relative to a valve seat 28 between an open and a sealed condition. The valve member 60 is biased into the sealed condition using a biasing spring 61, the biasing spring braced against periphery of the valve chamber provided in the shaft 14 in order to limit the movement of the biasing spring 61.

[00105] As mentioned above, the valve member 61 is biased into the sealed condition and requires a force to displace the valve member 61 from the seat 28 to move the valve member 61 to the open condition allowing material to flow past the valve member 61. This occurs typically when the shaft 14 is forced rearwardly manually against the biasing force of the main spring 17. This action forces the material in the charging chamber 42 against the valve member 61 which displaces the valve member 61 from the seat 28.

[00106] Preferably, an enlarged seat 29 is provided in order to mount the other end of the main spring 17 to the shaft 14. A circumferential shoulder 30 is provided for abutment of the main spring 17. The main spring 17 is normally received about the seat 29 and deformation of the spring 17 may be required in order to mount the spring 17 properly. The spring 17 is typically maintained on the seat through a friction fit.

[00107] There is also preferably a recess 31 formed by providing an enlarged annular portion 32 spaced from the sea 29t. The recess 31 is typically circumferential and allows proper seating and attachment of the protection boot (not shown) to the shaft 14. A clamping device is normally used to clamp the boot to the shaft.

[00108] The protection boot is normally a resilient boot provided to enclose the moving parts of the hand pump in order to prevent dust and other detritus from invading the mechanism. The protection boot may contain a lubricant.

[0100] An attachment thread 33 is provided on the shaft end opposite the piston head 15 in order to attach the supply conduit to the shaft 14 such that material provided through the supply conduit can flow into the bore 16 in the shaft 14, through the second valve assembly when able and into the charging chamber. The supply conduit is normally a flexible tube or pipe.

[00109] In use, the hand pump is assembled and connected to a supply conduit normally a flexible tube or pipe which is in turn connected to a material source. The shaft is then forced rearwardly and released to vent any air in the charging chamber and upon release, will act to open the first valve assembly and draw material into the charging chamber. The material cannot flow forwardly from the charging chamber because of the second valve assembly which is biased into the closed condition. Once the charging chamber is charged with material, depression of the shaft rearwardly, will force the material in the charging chamber forwardly from the hand pump and releasing the manual discharge force, will restart the charging cycle. In this manner, a measured charge of material is dispensed as required with recharging taking place after each discharge.

[0100] Although not illustrated (it has been removed for clarity) the protection boot is a resilient boot provided to enclose the moving parts of the hand pump 10 in order to prevent dust and other detritus from invading the mechanism. The protection boot will usually contain a lubricant.

[0101] Figure 11 is a cross sectional view of an alternative embodiment of the present invention showing the location and operation of the valves in a preferred embodiment.

[0102] In the present specification and claims (if any), the word ‘comprising’ and its derivatives including ‘comprises’ and ‘comprise’ include each of the stated integers but does not exclude the inclusion of one or more further integers.

[0103] Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0104] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims (16)

1. A hand pump apparatus for noxious or corrosive materials, the hand pump including: a tubular housing with a bore therethrough, a housing outlet at a forward end of the tubular-housing, a shaft associated with a piston head adapted for reciprocal .movement relative to the housing, the shaft having a bore therethrough with an inlet and an outlet, a first valve assembly associated with the bore of the housing, a second valve assembly located at the inlet end of the shaft and assoc iated with the bore of the shaft with a charging chamber defined between the first and second valve assemblies, such that movement of the shaft rearwardiy relative to the housing forces material in the charging chamber out through the housing outlet during a discharging phase and movement of the shaft forwardly relative to the housing charges the charging chamber with material through the bore in the shaft during a charging phase, wherein the shaft and the housing are concentric and the hand pump discharges material during the discharge phase only.

2. A hand pump apparatus as claimed in claim 1 wherein the shaft is biased into the charged condition rather than into the discharge condition by a shaft biasing member.

3. A hand pump apparatus as claimed in claim 1 or c laim 2 wherein the tubular housing and shaft of the hand pump are coaxial with one another and concentric and the respective bores of the housing and the shaft are coaxial.

4. A hand pump apparatu s as claimed in any one of the preceding claims wherein adj ustment of the size of the charge in order to allow the user control metering of the material expelled or delivered is accomplished by providing different spacers onto the shaft in order to change a length of a stroke of the shaft relative to the housing.

5. A hand pump apparatus as claimed in any one of the preceding c laims wherein the housing defines the charging chamber therein and also provides a guide for the reciprocal action of the shaft/piston head.

6. A hand pump apparatus as claimed in any one of the preceding claims wherein the housing includes three components, namely a head component, a body component and a tail component attached relative to one another.

7. A hand pump apparatus as claimed in claim 6 wherein the tail component includes a housing inlet provided with an attachment configuration provided to attach a supply conduit thereto.

8. A hand pump apparatus as claimed in claim 6. or claim 7 wherein the tail component is provided with a first bore portion which is an entry bore to the housing and to the charging chamber.

9. A hand pump apparatus as claimed in claim 8 wherein, the first bore portion is coaxial with the charging chamber, the bore in the body component and also with the bore in the shaft. 1Q. A hand pump apparatus as claimed in claim 8 or claim 9 wherein the first valve assembly is located toward an inlet end of the of the first bore portion bore and includes a first valve member which is movable relative to a first valve seat between an open and a sealed condition, the first valve member biased into the sealed condition using a first biasing member, requiring a force to displace the first valve member from the first valve seat to move the first valve member to the open condition allowing material to flow past the first valve member which occurs when the shaft is released after discharge of the charging chamber upon which a shaft biasing means forces the shaft forwardly again which in turn creates a lower pressure volume in the charging chamber which will draw material into the charging chamber against the first valve member which displaces the first valve member from the first valve seat.

11. A hand pump apparatus as claimed in claim 10 wherein the first valve assembly is located at least partially between the tail portion and an entry fitting,

12. A hand pump apparatus as claimed in any one of claims 6 to 11 wherein a first seating .portion is provided on the head component for seating a shaft biasing member relative thereto and a second seating portion is provided relative the shaft for seating the shaft biasing member relative thereto.

13 . A hand pump apparatus as claimed in claim 12 wherein a protection boot is provided about the shaft biasing member and mounted to the head component and mounted relative the shaft.

14. A hand pump apparatus as claimed in any one of the preceding claims wherein the inlet to the bore in the shaft commun icates with the charging chamber of the housing such that material exiting the charging chamber does so via the bore in the shaft.

15. A hand pump apparatus as claimed in any one of the preceding claims wherein the shaft and piston head is provided in a two-part assembly with a unitary shaft and a separate but attachable piston head.

16. A hand pump apparatus as claimed in any one of the preceding claims wherein the shaft is movable such that the piston head reciprocates within the bore in the housing to define a charging chamber and then, when forced, to reduce the volume of the charging chamber defined in order to expel material from the charging chamber and the hand pump. ] 7. A hand pump apparatus as claimed in claim 15 or claim 16 wherein the second valve assembly includes a second valve member which is movable relative to a second valve seat between an open and a sealed condition, the second valve member biased into the sealed condition using a second biasing member, requiring a force to displace the second valve member from the second valve seat to move the second valve member to the open condition allowing material 'to· flow past the second valve member which occurs when the shaft is moved rearwardly under manual force against the biasing force of the shaft biasing member forcing the material in the charging chamber against the second valve member which displaces the second valve member from the second valve seat.

18. A hand pump apparatus as claimed in any one of the preceding claims wherein a measured charge of material is dispensed as required with recharging taking place after each discharge.