TECHNICAL FIELD

[0001 ] The present invention relates to a valve control assembly. In particular, the present invention relates to a valve control assembly adapted to reduce the loss of cylinder pressure in a reciprocating engine.

BACKGROUND

[0002] Reciprocating engines (also known as piston engines) are well known and use one or more pistons to convert pressure into rotational motion. The most common type of reciprocating engine is an internal combustion engine, which converts chemical energy into heat energy through the combustion of a fuel. This is, in turn, used to drive the reciprocating movement of pistons to produce a rotating motion in a crankshaft or the like.

[0003] Conventional reciprocating engines suffer from a number of drawbacks. For instance, the efficiency of converting chemical energy into mechanical energy is moderate at best. This is because chemical energy from the fuel must first be converted into heat energy during combustion, which is then able to be harnessed and used as mechanical energy. During this process, a significant amount of energy is lost as heat dissipates through the reciprocating engine structure, coolant fluid or to the atmosphere through the exhaust mechanism. Accordingly, designers, builders and inventors are continuously searching for methods to manage heat loss.

[0004] Some attempts to overcome these drawbacks have been made. One example of this is the “temperature swing” insulation concept of using silica-reinforced porous anodized aluminium (SiRPA) to achieve heat loss reduction by means of heat rejection and an increase in exhaust energy and piston work. However, while this may reduce the loss of energy through heat dissipation, it does not eliminate it, nor does it lessen the reliance on fossil fuels for the operation of conventional reciprocating engines.

[0005] In addition, an ignition based reciprocating engine not only burns fossil fuels, but burn considerable volumes of air, which increases the concentration of hazardous aerosols and gaseous chemicals in the lower atmosphere resulting in reduced air quality, and also health implications for humans, flora and fauna.

[0006] Further, the use of internal combustion engines in certain locations (such as underground mines) may cause health and safety issues due to the emission of heat and combustion products. [0007] Some attempts, in the form of reciprocating engines driven by compressed air or steam (or other hot gasses), have been made to overcome these issues. However, as with conventional internal combustion engines, these engines suffer from a loss of cylinder pressure due to issues with the operation of valves that time the fluid exchange in an engine cylinder.

[0008] Thus, there would be an advantage if it were possible to provide an apparatus or assembly for reducing or eliminating the loss of cylinder pressure in a reciprocating engine.

[0009] It will be clearly understood that, if a prior art publication is 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

[0010] Embodiments of the present invention provide an assembly for reducing loss of cylinder pressure in a reciprocating engine, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

[001 1 ] According to a first aspect of the present invention, there is provided a valve control assembly for a reciprocating engine, the valve control assembly comprising a rotating drive member, the rotating drive member including at least a pair of profile portions, wherein each of the pair of profile portions is operatively associated with an attachment member, the attachment member being adapted for attachment to a pair of valve members such that rotation of the rotating drive member results in movement of the valve members between an open position and a closed position in which at least a portion of the valve member abuts a valve seat.

[0012] According to a second aspect of the present invention, there is provided a reciprocating engine including one or more cylinders, wherein the valve control assembly according to the first aspect is associated with each of the one or more cylinders.

[0013] The rotating drive member may be of any suitable form. For instance, the rotating drive member may include a rotating disc, gear, wheel or the like. More preferably, the rotating drive member comprises a rotatable shaft. It is envisaged that the rotatable shaft may be connected at at least one end thereof to a drive source. Any suitable drive source may be used, such as a motor, engine, mains power, one or more batteries or the like, or a combination thereof. It is envisaged that actuation of the drive source may result in rotation of the rotatable shaft, particularly about a longitudinal axis thereof.

[0014] In an alternative embodiment of the invention, the drive source may comprise an endless belt, such as a timing belt, timing chain or the like. Thus, in this embodiment of the invention, the rotating drive member may be adapted to have a similar function to a camshaft. However, as previously stated, the valve members of the present invention are adapted for attachment to an attachment member operatively associated with the rotating drive member, whereas a conventional camshaft is not connected to a valve member, but is instead adapted to periodically abut the valve member in order to actuate its movement relative to an associated valve seat. Conventional camshafts suffer from the disadvantage that the actuation of the valve members, particularly at higher RPM, can lead to“valve bounce” in which the valve member does not adequately seal against the valve seat, leading to a loss of pressure in the cylinder.

[0015] The profile portions may be of any suitable size, shape or configuration. In some embodiments of the invention, the profile portions may extend outwardly from the surface of the rotating drive member, may comprise recessed portions within the rotating drive member, or may comprise a combination of the two. Most preferably, all of the at least a pair of profile portions may comprise recessed portions within the rotating drive member. Alternatively, the rotating drive member may be fabricated from a plurality of portions adapted for connection to one another. For instance, the rotating drive portion may comprise a shaft portion having a first diameter, and a plurality of profile portions having a second diameter, the second diameter being smaller than the first diameter. In these embodiments, it is envisaged that no part of the profile portions extend outwardly beyond the surface of the rotating drive member.

[0016] In embodiments of the invention in which the profile portions are of smaller diameter than the shaft portion of the rotating drive member, it is envisaged that profile portions may be located at any suitable orientation to the shaft portion. For instance, the profile portions may be located so as to be substantially co-axial with the shaft portion. Alternatively, the profile portions may be located so that their longitudinal axes are substantially parallel to, but offset from, the longitudinal axis of the shaft portion. In a particular embodiment of the invention, the profile portions may be located such that a portion of the outer surface of each of the profile portions is positioned substantially flush with the outer surface of the shaft portion.

[0017] It will be understood that the exact diameter of the profile portions relative to the diameter of the shaft portion of the rotating drive member will vary depending on the characteristics sought from the reciprocating engine.

[0018] The recessed portions of adjacent profile portions may be provided at any suitable orientation to one another. In a preferred embodiment, however, adjacent profile portions may be located at approximately 180° to one another about the circumference of the rotating drive member. [0019] As previously stated, the rotating drive member is provided with at least a pair of profile portions. In some embodiments of the invention each profile portion may be associated with a cylinder in a reciprocating engine. More preferably, however, the pair of profile portions may be associated with a cylinder in a reciprocating engine.

[0020] In some embodiments of the invention, the valve control assembly may be adapted to control valves associated with a plurality of cylinders. Thus, in this embodiment of the invention, the rotating drive member may be provided with a pair of profile portions for each cylinder with which the valve control assembly is associated.

[0021 ] It will be understood that, in embodiments of the invention in which each of the pair of profile portions is associated with a different cylinder, the adjacent profile portions may be located next to one another on the rotating drive member, or may be spaced apart from one another by a length of the shaft portion of the rotating drive member. When a pair of profile portions is associated with a single cylinder, it is preferred that the pair of profile portions are positioned next to one another, although it is possible that the profile portions may be spaced apart from one another by a length of the shaft portion of the rotating drive member.

[0022] As previously stated, each of the pair of profile portions is operatively associated with an attachment member. The attachment member may be operatively associated with the profile portions in any suitable manner. For instance, the attachment member may be integrally formed with the profile portion. Alternatively, the attachment members may be fabricated separately to the profile portions and adapted for fixed or removable connection thereto. More preferably, the attachment members are not connected to the rotating drive member, but are located in abutment with, or close proximity to, the rotating drive member such that rotation of the rotating drive member does not result in rotation of the attachment member. Instead, it is preferred that the rotation of the profile portions (as part of the rotating drive member) may result in substantially linear movement of the attachment member.

[0023] In embodiments of the invention in which the profile portions comprise recessed portions within the rotating drive member, it is envisaged that as the rotating drive member rotates, the recessed portion may transition between facing upwardly and facing downwardly. Any suitable rotation of the rotating drive member may result in the transition of the recessed portion transition between facing upwardly and facing downwardly, although it is envisaged that an approximately 180° rotation of the rotating drive member may result in the recessed portion transitioning from facing upwardly to facing downwardly, and vice versa.

[0024] In this embodiment, it is envisaged that at least a portion of the attachment member may be located, and retained, in abutment with the profile portion. Thus, when the profile portion is oriented so as to be facing upwardly, the attachment member may be at its lowest vertical point. Conversely, when the profile portion is oriented so as to be facing downwardly, the attachment member may be at its highest vertical point. Thus, rotation of the rotating drive member may move the attachment member between an upper position (the highest vertical point) and a lower position (the lowest vertical point).

[0025] In a preferred embodiment of the invention, the attachment member may be adapted to surround or overlie at least a portion of the profile portion with which it is operatively associated.

[0026] The rotating drive member may be adapted to rotate relative to the attachment member. Thus, in some embodiments of the invention, a lubricant may be provided on the attachment member, the profile portion, or both to ensure smooth rotational movement of the rotating drive member relative to the attachment portion. Alternatively, one or more bearings may be provided to ensure the smooth rotational movement of the drive member relative to the attachment portion.

[0027] Any suitable bearing may be used, although in a preferred embodiment of the invention, a rolling-element bearing may be provided. Any suitable rolling-element bearing may be provided, such as, but not limited to, a ball bearing, roller bearing, CARB bearing or the like, or any suitable combination thereof. In some embodiments of the invention, a rolling-element bearing having a bore therein may be provided. In this embodiment of the invention, the rotating drive member may pass through the bore such that the rolling-element bearing surrounds the rotating drive member. In this embodiment, the attachment portion may not abut the rotating drive member, but may instead abut the rolling-element bearing.

[0028] In another embodiment of the invention, a rolling-element bearing may be located so that an outer surface of the bearing abuts an outer surface of the rotational drive member or, more preferably, an outer surface of a profile portion. In this embodiment of the invention, it is envisaged that the longitudinal axis of the rolling-element bearing may be substantially parallel to the longitudinal axis of the rotating drive member and the profile portions, but may be offset therefrom (i.e. may not be co-axial therewith). Preferably, rotation of the rotating drive member results in rotation of the rolling-element bearing. It is envisaged that the rotation of the rolling- element bearing may be in the opposite direction to the rotation of the rotating drive member.

[0029] In this embodiment of the invention, the rolling-element bearing may be of any suitable form. However, in a preferred embodiment of the invention, the rolling-element bearing may be a roller bearing. [0030] The one or more bearings may be located in any suitable location relative to the rotating drive member. In a preferred embodiment of the invention, however, it is envisaged that the one or more bearings may be positioned so as to be in abutment with an upwardly facing surface of the rotating drive member and, more specifically, in abutment with an upwardly facing surface of a profile portion. It is envisaged that the one or more bearings may rotate about their longitudinal axes and may also move vertically as the recessed portion transitions from facing upwardly to facing downwardly, and vice versa. However, it is preferred that the one or more bearings are substantially precluded from lateral movement relative to the rotating drive member.

[0031 ] The rotating drive shaft and the one or more bearings may be of substantially the same diameter, or may be of different diameters. In a preferred embodiment of the invention, however, the rotating drive member and the one or more bearings may be adapted to rotate at substantially the same speed.

[0032] Preferably, each attachment member may be operatively associated with both a profile portion and a bearing. In some embodiments of the invention, each attachment member may be retained in abutment with both a profile portion and a bearing. However, it is envisaged that at least a portion of the bearing may be located between the rotating drive member and the attachment member. Thus, it is envisaged that the bearing may follow the circumference of the profile portion as the rotating drive member rotates.

[0033] Preferably, the attachment member may be adapted to move vertically with the bearing, but may be substantially precluded from rotation movement or lateral movement relative to both the rotating drive member and the bearing.

[0034] As previously stated, the attachment member is adapted for attachment to a pair of valve members. The attachment member may be attached to the valve members using any suitable technique. For instance, the valve members may be integrally formed with the attachment member, or may be fabricated separately therefrom and adapted for fixed or temporary attachment thereto. In some embodiments of the invention, the valve members may be attached to the attachment members using one or more mechanical fasteners (screws, nails, bolts, rivets or the like). Alternatively, the valve members may be attached to the attachment member using one or more retention members, such as a clamp, clasp, tie, hook or the like, or any suitable combination thereof.

[0035] In a particular embodiment of the invention, the attachment member may be provided with a pair of guide portions. It is envisaged that each guide portion may be adapted to be operatively associated with one of the pair of valve members. The pair of guide portions may be of any suitable form. In a preferred embodiment of the invention, the guide portions may comprise bores extending at least partway through the attachment member.

[0036] It is envisaged that the valve members may be at least partially received in the guide portions. It is also envisaged that the valve members may be retained in the guide portions. In some embodiments of the invention, the valve members may be retained in frictional engagement with the guide portions. Alternatively, in embodiments of the invention in which the guide portions comprise bores, a screw-threaded portion may be provided on the inner surface of the bore, the screw-threaded portion being adapted to engage with a complementary screw- threaded portion of the valve members. In this way, the valve members may be retained in screw-threaded connection with the guide portions.

[0037] In other embodiments of the invention, an end region of the valve member may pass entirely through the bore and one or more retention members may be used to prevent the valve member from being retracted through the guide portion. For instance, the retention members may comprise clasps, clamps or the like adapted to engage with the end region of the valve member. Alternatively, the retention members may comprise one or more nuts or the like adapted to engage with the end region of the valve member. In this embodiment of the invention, it is envisaged that the diameter of the retention members may be greater than the diameter of the bore, thereby preventing the valve member from being retracted through the bore. It is envisaged that the position of the valve member relative to the attachment member may be adjusted as required to ensure adequate sealing of the valve member against the valve seat and so on.

[0038] The pair of guide portions may be provided at any suitable orientation to one another. For instance, both guide portions may be provided on the same side of the attachment member, such that both valve members are positioned on the same side of the rotating drive member. More preferably, however, a guide portion is provided on opposing sides of the attachment member such that, in use, a valve member is positioned on each side of the rotating drive member.

[0039] In this way, it is envisaged that the valve control assembly may be substantially balanced by locating a valve member on either side of the rotating drive member. Balancing the valve control assembly in this manner also helps to reduce or eliminate the possibility of the attachment member rotating relative to the rotating drive member.

[0040] The valve members may be oriented at any suitable angle. Flowever, it is preferred that the valve members are positioned substantially perpendicular to the longitudinal axis (also the rotational axis) of the rotating drive member. In practice, it is envisaged that the rotating drive member may be positioned in a substantially horizontal orientation, while the valve members may be positioned in a substantially vertical orientation. Thus, it is envisaged that the cylinders in the reciprocating engine may also be positioned in substantially vertical orientations. Further, the valve members may be positioned substantially parallel to one another.

[0041 ] The pair of valve members may be positioned at any suitable height relative to one another. For instance, the pair of valve members may be positioned offset vertically from one another. More preferably, the pair of valve members is positioned at substantially the same height as one another. In this way, the pair of valve members is adapted to perform the same function in relation to a cylinder of a reciprocating engine. For instance, a pair of valve members associated with a first profile portion may be adapted for use in connection with the inlet side of a cylinder, while a pair of valve member associated with a second profile portion may be adapted for use in connection with the outlet side of a cylinder. Thus, in this embodiment of the invention, the cylinder may be provided with a pair of inlet valves and a pair of outlet valves.

[0042] The valve members may be of any suitable form. Flowever, in a preferred embodiment of the invention, the valve members comprise valve stems. In particular, the valve members may comprise valve stems of poppet valves. Thus, in this embodiment of the invention, it is envisaged that the opposed end of the valve member to the end connected to the attachment member may be provided with a valve head.

[0043] As previously stated, the valve members abut valve seats in the closed position. Preferably, the valve seats are located in a cylinder, and particularly a cylinder in a reciprocating engine. In a particular embodiment of the invention, it is envisaged that the valve head may be the portion of the valve member that abuts the valve seat, and forms a seal thereagainst.

[0044] It is envisaged that, in the open position, the valve members may be withdrawn from abutment with the valve seat. The valve members may be withdrawn any suitable distance, and it is envisaged that the distance (e.g. the vertical distance) between the closed position and the open position may depend on the desired characteristics of the engine. Flowever, it is envisaged that the distance between the closed position and the open position may be sufficient to allow a sufficient quantity of fuel (for an internal combustion reciprocating engine) or gas (for an ignition less reciprocating engine) to enter the cylinder through the inlet valves. Similarly, it is envisaged that the distance between the closed position and the open position may be sufficient to allow sufficient exhausting of the cylinder through the exhaust valves.

[0045] In a preferred embodiment of the invention, each of the valve members may be operatively associated with a spring, and, in particular, a torsion spring. The valve members may be associated with the springs in any suitable manner, although in a preferred embodiment of the invention the valve stem may be positioned such that it is surrounded by the helical torsion spring. It is envisaged that the spring may be retained on the valve member by the lower end of the spring abutting the valve head, the valve head heaving a greater diameter than the helical spring.

[0046] In some embodiments of the invention, each spring may be substantially identical to one another. More preferably, however, different springs may be used depending on the duty of the valve member with which the spring is associated. In some embodiments, it is envisaged that the springs associated with the outlet valves of the cylinder may be relatively large and heavy. This is because the outlet valves require a torsion pressure greater than the internal chamber pressure and the force created against the surface of each exhaust valve to overcome the residual exhaust pressure which remains within the cylinder as the piston reaches bottom dead centre and opens the valves to exhaust the cylinder.

[0047] In contrast, the springs associated with the inlet valves of the cylinder may be relatively small and light. This is because only light spring pressure is required as the main function of the springs is to act as a cushioning device as the inlet valve closes.

[0048] Although it is envisaged that the valve control assembly of the present invention may be used in connection with an internal combustion-driven reciprocating engine, it is preferred that the valve control assembly of the present invention may be used in connection with an air- driven (or ignition-less) reciprocating engine.

[0049] Thus, in a second aspect, the invention resides broadly in a reciprocating engine including one or more cylinders, wherein a valve control assembly according to the first aspect is associated with each of the one or more cylinders.

[0050] Preferably, the reciprocating engine is an air-driven (or ignition-less) engine.

[0051 ] It is envisaged that the reciprocating engine may be used in any suitable situation, and it is envisaged that the reciprocating engine of the present invention may be used to replace conventional reciprocating engines in any suitable application.

[0052] For instance, the reciprocating engine of the present invention may be used as an engine for a vehicle. In other embodiments of the invention, the engine may be used for power generation, cogeneration (also referred to as combined heat and power or CHP) and the like.

[0053] The engine of the present invention may be used as a primary engine, or may be used as a secondary or back-up engine. In the latter situation, it is envisaged that the engine of the present invention may be adapted to begin operation in the event of a failure of a primary engine (for instance, due to power failure, battery failure, running out of fuel, scheduled maintenance, unexpected breakdowns and so on).

[0054] In other embodiments, the engine may be used to supply electrical power to one or more electrical devices. The engine may supply electrical energy directly to the one or more electrical devices and/or may generate electrical energy to be stored and subsequently used the one or more electrical devices. The electrical energy generated by the engine may be stored in any suitable manner. For example, the electrical energy may be stored in one or more batteries.

[0055] The one or more electrical devices may be of any suitable form. The one or more electrical devices may be for domestic, commercial and/or industrial usage. For instance, the one or more electrical devices may be used in agriculture, mining, forestry, manufacturing and the like, or any suitable combination thereof.

[0056] In a specific embodiment of the invention, the one or more electrical devices may be used for communications purposes, and particularly telecommunications purposes. In a specific embodiment, the one or more electrical devices my comprise telecommunications transmission devices. Thus, in this embodiment, an engine of the present invention may be associated with a telecommunications transmission tower or the like.

[0057] The present invention provides numerous advantages over the prior art. Firstly, the profile portions provide greater control over the movement of the valve members relative to the valve seats as it is the rotation of the rotating drive member that controls movement of the valve members due to the connection of the valve members to the attachment member. This reduces or eliminates the incidence of valve bounce in which the valve member abuts the valve seat but “bounces” out of abutment, thereby reducing the effectiveness of the seal between the valve member and the valve seat.

[0058] In addition, having valve members that travel in a direction parallel to the cylinder piston provides a variety of benefits over traditional angular methods. Specifically, valve members that travel parallel to the piston reduce or eliminate the possibility of a damaging interaction between the valves and the piston crown in the event of a timing belt or chain failure. In traditional cylinders in which the valves are positioned at an angle to the piston, a timing belt or chain failure would typically damage or destroy the piston crown and/or the valves. In contrast, in the present invention, the piston crown would be able to push the valves as the piston and the valve members move in the same direction. Thus, the valve members are not pushed at an angle by the piston crown in the event of a timing belt or chain failure.

[0059] 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. [0060] 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

[0061 ] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

[0062] Figure 1 illustrates an isometric view of a valve control assembly according to an embodiment of the present invention;

[0063] Figure 2 illustrates a side view of a valve control assembly according to an embodiment of the present invention;

[0064] Figure 3 illustrates an end view of a valve control assembly according to an embodiment of the present invention; and

[0065] Figure 4 illustrates a schematic diagram of a reciprocating engine according to an embodiment of the present invention when used to supply electrical power to a telecommunications transmission tower.

DETAILED DESCRIPTION

[0066] Figures 1 -3 illustrate isometric, side and end views, respectively, of a valve control assembly 10 according to an embodiment of the present invention. In these Figures it may be seen that the valve control assembly 10 includes a rotating drive member 1 1 . The rotating drive member 1 1 is connected at a first end 12 thereof to a drive mechanism, such as a timing belt or chain (not shown).

[0067] As can be seen particularly in Figure 2, the rotating drive member 1 1 comprises two pairs of profile portions 13a, 13b, 14a, 14b. One pair of profile portions 13a, 13b is associated with a cylinder 15 of a reciprocating engine, while the second pair of profile portions 14a, 14b is, in the embodiment shown in Figure 2, not associated with a cylinder. However, it will be noted that the valve control assembly of Figure 2 has the ability to be associated with two cylinders.

[0068] The profile portions 13a, 13b are of smaller diameter than the shaft portion 17 of the rotating drive member 1 1 , and include recessed portions 18a, 18b within the rotating drive member 1 1 . The recessed portions 18a, 18b are disposed at 180° about the circumference of the rotating drive member 1 1 to one another such that, as illustrated best in Figure 2, a first recessed portion 18a is facing downwards, the second recessed portion 18b is facing upwards. Thus, the profile portions 13a, 13b, 14a, 14b do not extend outwardly beyond the outer surface of the shaft portion 17 of the rotating drive member 1 1 . In the embodiment of the invention shown in Figures 1 -3, a portion of the outer surface of the profile portions 13a, 13b, 14a, 14b is located flush with the outer surface of the shaft portion 17 of the rotating drive member 1 1 .

[0069] The valve control assembly 10 further comprises a pair of attachment members 16a, 16b. Each of the attachment members 16a, 16b is operatively associated with a profile portion 13a, 13b. Specifically, attachment member 16a is operatively associated with profile portion 13a, while attachment member 16b is operatively associated with profile portion 13b.

[0070] A pair of valve members in the form of valve stems 19 is connected to each of the attachment members 16a, 16b. In the embodiment of the invention shown in Figures 1 -3, the valve stems 19 are poppet valve stems. A first end of the valve stems passes through a guide portion 20 of the attachment members 16a, 16b and is retained therein through the use of retention members in the form of nuts 21 (best seen in Figure 1 ) that screw-threadedly engage with a screw-threaded portion of the valve stems 19.

[0071 ] The guide portions 20 are positioned on the attachment members 16a, 16b such that, one of the pair of valve stems 19 is located on each side of the rotating drive member 1 1 .

[0072] The second end of the valve stems 19 includes a valve head 22 adapted to form a seal against a valve seat 24 in the cylinder 15 when the valve stems 19 are in the closed condition.

[0073] In use, the rotating drive member 1 1 rotates about its longitudinal axis. A roller bearing 23 is associated with each profile portion 13a, 13b and is positioned in abutment with, and above, the rotating drive member 1 1 . The attachment members 16a, 16b are positioned so as to abut both the rotating drive member 1 1 and their respective roller bearing 23.

[0074] As the rotating drive member 1 1 rotates, the roller bearings 23 rotate in an opposite direction but does not move laterally. The roller bearings 23 will move vertically as the rotating drive member rotates about the rotating circumference of the profile portions 13a, 13b. Specifically, the roller bearings 23 will move from a lower position when a profile portion is facing vertically upwardly (i.e. profile portion 13b) to an upper position when a profile portion is facing downwardly (i.e. profile portion 13a). When the roller bearing 23 is in the lower position, the valve stems 19 are in the closed condition, i.e. the valve heads 22 are in abutment (and preferably sealing abutment) with respective valve seats 24. When the roller bearing 23 in in the upper position, the valve stems 19 are in the open condition, i.e. the valve heads are removed from the abutment with the valve seats 24, allowing either fluid to flow into the cylinder 15, or the cylinder 15 to be exhausted depending on the duty of the valve stem 19.

[0075] The attachment members 16a, 16b abut with, and partially surround, their respective roller bearings 23 and are also maintained in abutment with the rotating drive member 1 1 . As the rotating drive member 1 1 rotates, the roller bearings 23 support the respective attachment members 16a, 16b such that the attachment members 16a, 16b move vertically with the roller bearings 23. Lateral and rotational movement of the attachment members 16a, 16b (and therefore the valve stems 19) is substantially precluded.

[0076] As the rotating drive member 1 1 rotates, and the roller bearings 23 follow the circumference of the profile portions 13a, 13b, the valve stems 19 move vertically between the open and closed conditions. As a result, the valve stems 19 move in the same direction as the piston 25 within the cylinder 15. This is quite different to cylinders in conventional reciprocating engines in which the valve stems are located at an included angle of less than 90° to the direction of travel of the piston.

[0077] A helical spring 26 is provided over each valve stem 19 so that the springs 26 are constrained between the valve head 22 and a retention member 27 located on the valve stem 19. The purpose of the springs 26 is to ensure that the valve heads 22 move into, and are retained in, substantially sealing abutment with the valve seats 24 so as to reduce or eliminate cylinder pressure loss problems caused by valve“bounce” (i.e. the valve head bouncing out of abutment with the valve seat, resulting in a loss of cylinder pressure) in conventional reciprocating engines.

[0078] Figure 4 illustrates a schematic diagram of a reciprocating engine 100 according to an embodiment of the present invention when used to supply electrical power to a telecommunications transmission tower 101 .

[0079] In Figure 4, electrical energy is supplied to the telecommunications transmission tower 101 from either a pair of battery banks 102 or a direct current (DC) generator 103. The DC generator 103 is also is electrical communication with the battery banks 102, such that the DC generator 103 can be used to charge the battery banks 102 as needed. Alternating current (AC) electrical power is supplied to the DC generator 103 by an electric motor 104 connected to mains power 105. The AC power is converted to DC power by the DC generator 103 and then used to power the telecommunications transmission tower 101 and/or charge the battery banks 102. [0080] A reciprocating engine 100 according to the present invention is also associated with the DC generator 103. The reciprocating engine 100 is, in this embodiment, used as a backup to the electric motor 104 and it is envisaged that the reciprocating engine 100 will only be used to provide electrical energy to the DC generator 103 if the electric motor 104 is not in use (for instance, due to mains power failure, battery failure, scheduled maintenance, unexpected breakdowns and so on).

[0081 ] Both the electric motor 104 and the reciprocating engine 100 are associated with the DC generator 103 via an air clutch 106. It is envisaged that, when the electric motor 104 is not operational, the air clutch 106 may actuate such that the electric motor 104 is disconnected from the DC generator 103 and the reciprocating engine 100 is connected to the DC generator 103.

[0082] The reciprocating engine 100 is an air-driven engine. Air is received by the reciprocating engine 100 from a plurality of compressed air storage vessels 107 in fluid communication with the reciprocating engine 100. It is envisaged that, when the electric motor 103 is not operational, an air flow valve 108 is opened to allow compressed air to flow from the storage vessels 107 to the reciprocating engine 100 in order to generate electrical energy to power the telecommunications transmission tower 101 . The electrical energy generated by the reciprocating engine 100 may either power the telecommunications transmission tower 101 directly, or may be used to charge the battery banks 102, which in turn provide the electrical energy to power the telecommunications transmission tower 101 .

[0083] Compressed air in the compressed air storage vessels 107 is generated using an air compressor 109 in fluid communication with the compressed air storage vessels 107. The air compressor 109 is powered by mains power 105.

[0084] 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.

[0085] 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.

[0086] 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.