Field of the Invention

This invention relates to a valve plate and, more specifically to a valve plate used in compressors. Background to the Invention

Valve plates used in compressors experience high wear and therefore require regular checking and, if necessary, refurbishment and/or cleaning.

The cost of replacement parts for valve plates of popular compressors has become very high and the cost of replacing the entire valve plate when it is no longer possible to refurbish an old one is of course even higher.

A part of conventional valve plates such as those of compressors manufactured by Copeland ^® that experience high wear are the disc valves that open into the discharge side of the valve plate.

Due to their construction, discus valve plates are difficult to clean and their individual parts are prone to failure, which in turn may damage other parts of the compressor.

In use, each disc valve is fitted into a circular opening in the valve plate around which opening an annular opening is defined.

A suction reed having an annular body and two opposed tabs extending therefrom is located on the suction side of the valve plate and overlays the annular opening, thereby sealing it.

The valve plate itself is made up by three individual plates with fluid flow passages defined between the plates. This makes cleaning of the valve plate very cumbersome.

Although reed valves have been used instead of disc valves on the discharge side of valve plates, it is not possible to use them in combination with a suction reed as described above, because of the design of the specific valve plate and cylinder head combination currently used. Currently, users therefore have no option but to purchase expensive replacement parts for compressor valve plates or an entire new valve plate when refurbishment becomes necessary due to wear and tear.

The inventor therefore believes that a need exists for providing a valve plate that is easier to clean and refurbish than valve plates described above and which can take the place of an original valve plate once said plate is no longer fit for use due to wear and tear and is too expensive to replace or refurbish.

Summary of the Invention

According to the invention, there is provided a valve plate including:- - a body portion formed by a single plate;

- one or more suction opening(s) defined in the body portion, the suction opening(s) being shaped to form a portion or portions of an annulus; and

- one or more discharge openings defined in the body portion, at least a major portion of the discharge opening(s) being located within an imaginary circle formed by extending an inner diameter of the partial annulus formed by the suction opening(s).

The thickness of the body portion may be the same or less than that of a conventional valve plate. The thickness of the body portion may be between 5 mm and 8,5mm and is typically at least 5,8 mm and at most 7,8 mm. In a preferred embodiment, the body portion may be 6 mm thick.

The body portion may be manufactured from steel.

The suction opening(s) may be provided with a chamfer along at least a substantial portion thereof on the discharge side of the valve plate to improve fluid flow therethrough. In a preferred embodiment of the invention, two suction openings may be provided which together form a set forming about one half of an annulus.

Two spaced apart sets of suction openings may be defined in the body portion, i.e. four suction openings in total. Two discharge openings may be defined in the body portion per set of suction opening(s), i.e. four in total.

In an alternative embodiment of the invention, three spaced apart sets of suction openings may be defined in the body portion, i.e. six suction openings in total. One discharge opening may be defined in the body portion per set of suction opening(s), i.e. three in total.

The discharge openings may be circular in shape. Alternatively, the discharge openings may be oblong in shape to improve fluid flow therethrough and may include chamfers to further improve fluid flow. In use, a suction reed as described above may be arranged on the suction side of the valve plate so as to overlay the suction opening(s), thereby sealing them.

The suction reed may be held in place by two pins, each engaging one of two opposed tabs of the suction reed thereby allowing a slight movement of the reed away from the suction openings, typically less than 0.5 mm. The pins may be fitted to a housing of a compressor, thereby allowing the suction reed to float below the suction openings during a down stroke of a compressor piston, allowing fluid flow through the suction openings.

Openings that are complementary in shape to the cross-sectional shape of the pins and which extend about half way into the valve plate may be provided for receiving the pins therein.

During fitting of the suction reeds to the valve plate, the pins may be located in the openings and held in place with a tool which may engage a peripheral zone of the openings.

When the tool is struck from above, the peripheral zone of the openings is displaced inwardly, thereby creating a tight fit with the pins. The pins may stand proud of the openings to permit easy gripping and removal thereof.

Alternatively, the suction reed may be held in place by two rivets fixed to the valve plate, both rivets engaging a first of two opposed tabs of the suction reed thereby allowing free movement of the second tab. Conventional reed valves may be arranged on the discharge side of the valve plate so as to overlay the discharge opening(s), thereby sealing them.

Due to the particular location of the suction and discharge openings in the body portion, the reed valves do not overlay the suction opening(s) and the suction reed(s) do(es) not overlay the discharge opening(s).

It is to be appreciated, that the suction opening(s) may define a portion of a geometric figure other than an annulus, e.g. of a square or rectangle, bearing in mind that the suction reed would need to be of a complementary shape so as to be able to overlay and seal the suction opening(s). The body portion may be provided with apertures for bolts, etc. that may be located in the same position as they would be on a conventional valve plate.

A valve plate in accordance with the present invention may be provided with its own cylinder head, thereby obviating the need to conform exactly to the shape of a valve plate that it is to replace in use. The cylinder head may be manufactured from aluminium or cast iron or cast steel.

It has been found that when three openings for accommodating three bolts are provided along a central longitudinal zone of the valve plate and cylinder head, this leads to improved longevity of a gasket located between the valve plate and cylinder head. The bolts may be inserted through threaded openings in the cylinder head into complementary openings in the valve plate, thereby connecting the two. The bolts may be secured using a threadlocking product such as, for example, Loctite ^® Threadlocker to inhibit gas leakage via the thread.

A gasket and cap may be provided on an exterior surface of the cylinder head to overlay the openings and bolts, thereby further inhibiting gas leakage from the cylinder head in use.

When replacing an existing valve plate with a valve plate in accordance with the present invention, the old cylinder head may therefore be removed. An additional cylinder head may be provided and the new cylinder head may be nested in the additional cylinder head, thereby forming a chamber between the two heads.

Fluid may be fed through the chamber to absorb heat from the two cylinder heads, thereby cooling the heads. The fluid fed through the chamber may be water.

In this manner, a compressor may be used as a source of hot water, whilst prolonging the life span of the compressor.

Detailed Description of the Invention

The invention will now be described by way of the following, non-limiting examples with reference to the accompanying drawings.

In the drawings:-

Figure 1 shows a plan view of a suction side of a valve plate in accordance with the present invention with suction reeds shown in dotted lines;

Figure 2 shows a plan view of a discharge side of a valve plate in accordance with the present invention with reed valves shown in dotted lines;

Figure 3 shows a plan view of a suction side of a valve plate in accordance with the present invention;

Figure 4 shows a plan view of a discharge side of a valve plate in accordance with the present invention; Figure 5 shows a cross-sectioned side view of the valve plate of Figures 3 and 4 fitted onto a cylinder head in a compressor; and

Figure 6 is a plan view of the interior of a cylinder head to be used in combination with a valve plate in accordance with the present invention.

In the drawings, reference numeral 10 generally indicates an embodiment of a valve plate in accordance with the present invention. The valve plate 10 includes a body portion 12 formed by a single plate, two sets 14 of suction openings 16, defined in the body portion, each set 14 of suction openings 16 being shaped to form about half an annulus.

The width of each suction opening 16 on the suction side of the valve plate 10 (Figure 1 ) is about 7.5 mm.

Two discharge openings 18 are defined in the body portion 12 per set 14 of suction openings.16.

The discharge openings 18 are located within an imaginary circle formed by extending an inner diameter of the partial annulus formed by each set 14 of suction openings 16 as can best be seen in Figure 1 .

In the embodiment shown, the four discharge openings 18 are circular in shape and have a diameter of about 14 mm. However, the discharge openings 18 can be oblong in shape to improve fluid flow therethrough.

The thickness of the body portion 12 is typically less than that of a plate that it is to replace in use. The thickness of the body portion 12 is at least 5,8 mm and at most 7,8mm.

The body portion 12 is manufactured from steel.

As can be seen in Figure 2, the suction openings 16 are provided with a chamfer 20 along at least a substantial portion thereof on the discharge side of the valve plate 10 to improve fluid flow therethrough.

The chamfer 20 is about 2.5 mm wide and has an inclination of about forty five degrees.

In use, two suction reeds 22 (shown in dotted lines in Figure 1 and in solid lines in Figure 3) as described above are arranged on the suction side of the valve plate 10 so as to overlay the suction openings 16, thereby sealing them.

Each suction reed 22 is held in place by two pins, each pin engaging one of two opposed tabs 26 of the suction reed 22. Openings 24 that are complementary in shape to the cross-sectional shape of the pins and which extend about half way into the valve plate 10 are provided for receiving the pins therein.

During fitting of the suction reeds 20 to the valve plate 10, the pins are located in the openings 24 and held in place with a tool (not shown) which engages a peripheral zone of the openings.

When the tool is struck from above, the peripheral zone of the openings 24 is displaced inwardly, thereby creating a tight fit with the pins. The pins stand proud of the openings 24 to permit easy gripping and removal thereof in the event that the valve plate 10 needs to be cleaned or a suction reed 22 needs to be replaced.

The suction reeds 22 are sufficiently flexible to flex (less than 0.5 mm) away from the suction side of the valve plate 10 during a suction or down stroke of a piston 38 of a compressor 40, thereby permitting fluid flow through the suction openings 16 indicated by arrows "A" in Figure 5. Conventional reed valves 30 (shown in dotted lines in Figure 2 and in solid lines in Figure 4) are arranged on the discharge side of the valve plate 10 so as to overlay the discharge openings 18, thereby sealing them.

The free ends of the reed valves 30 overlaying the discharge openings 18 flex away from the openings 18 when sufficient positive pressure is applied to them from the suction side of the valve plate 10 during an up stroke of the piston 38, thereby allowing fluid flow through the discharge openings 18 indicated by arrows "B" in Figure 5, while the suction reeds 22 are pressed against and seal the suction openings 16.

Each reed valve 30 is provided with a backing plate 42 to inhibit overflexing of a closure member 44 of the valve 30.

Openings 32 and circular recesses 34 having a diameter of about 19 mm and a depth of about 4mm are provided on the discharge side of the valve plate 10 to allow mounting of the reed valves 30 thereon. Due to the particular location of the suction and discharge openings 16 and 18 in the body portion 12, the reed valves 30 do not overlay the suction opening 16 and the suction reeds 22 does not overlay the discharge openings 18.

The body portion 12 is provided with apertures 36 for bolts, etc. that are located in the same position as they would be on a conventional valve plate.

The width w of the body portion is about 154 mm and its length is about 254 mm.

Referring now to Figure 6, a valve plate 10 in accordance with the present invention can provided with its own cylinder head 44, thereby obviating the need to conform exactly to the shape of a valve plate that it is to replace in use. It has been found that when three openings 28 for accommodating three bolts (not shown) are provided along a central longitudinal zone of the valve plate 10 and cylinder head 44, this leads to improved longevity of a gasket located between the valve plate 10 and cylinder head 10.

The bolts are inserted through threaded openings 46 in the cylinder head 44 into complementary openings 28 in the valve plate 10, thereby connecting the two. The bolts are secured using a threadlocking product such as, for example, Loctite® Threadlocker to inhibit gas leakage via the thread.

In addition, a gasket and cap (not shown) can be provided on an exterior surface of the cylinder head 44 to overlay the openings 46, thereby further inhibiting gas leakage from cylinder head 44 in use.

When replacing an existing valve plate with a valve plate 10 in accordance with the present invention, the old cylinder head is removed.

An additional cylinder head can be provided and the cylinder head 44 can be nested in the additional cylinder head, thereby forming a chamber between the two heads. Fluid can be fed through the chamber to absorb heat from the two cylinder heads, thereby cooling the heads. The fluid fed through the chamber is typically water. In this manner, a compressor can be used as a source of hot water, whilst prolonging the life span of the compressor. It is to be appreciated, that the invention is not limited to any particular embodiment or configuration as hereinbefore generally described and/ or illustrated.