Claims
- 1. An air compressor having two cylinders in V-shaped configuration mounted on a crankcase, an intercooler disposed between said cylinders for conducting air from one cylinder to the other, a fan mounted at an end of said crankcase and a fan shroud operably disposed about said fan, and said shroud further including:
- a scroll-shaped vane disposed around said fan for directing air from said fan;
- two projections extending upwardly in V-shaped configuration from said shroud;
- cooling air discharge passageways extending from said fan and vane into said shroud projections;
- a shroud back plate having two projections in V-shaped configuration corresponding to said shroud projections, said plate closing off said shroud and forming with said shroud a cooling air chamber for receiving cooling air from said fan and vane;
- transverse exhaust ports in ends of the backplate projections for exhausting cooling air from said chamber;
- deflector means disposed in operable alignment with said exhaust ports for directing cooling air over said respective cylinders; and
- a further exhaust port disposed in said back plate in general register with said intercooler means for directing cooling air from within said shroud over said intercooler.
Parent Case Info
This is a division, of application Ser. No. 07/252,695, filed Oct. 3, 1988, now U.S. Pat. No. 4,915,594, which is, in turn a divisional of U.S. patent application Ser. No. 06/856,645, filed Apr. 25, 1986, now U.S. Pat. No. 4,801,250.
The efficiency and reliability of an air compressor are generally functions of a number of factors, primarily having to do with the way air is moved, and its temperature controlled, throughout the process.
This invention relates to air compressors and more particularly to improvements in the valving, intake manifolds, crankshafts and to cooling of air in air compressors, which improve efficiency and reliability and which reduce operating noise.
A typical, industrial quality air compressor may currently be of the two-stage type wherein air is first compressed in one cylinder, then transferred to another cylinder from where it is moved to a receiver. Such cylinders may be oriented in a "V" configuration, and driven by a belt driven pulley, for example, at a speed of about 900 to 1000 rpm.
In the past, such compressors have used, among other arrangements, valve plates disposed between the cylinder and cylinder head to provide appropriate intake and exhaust valving for that cylinder. While various types of valves have been used in connection with such plates, it is common to find reed valves mounted thereon. Such reed valves are generally a flexible reed of metal, fixed at one end to the valve plate or associated cylinder head for closing appropriate ports in the head or valve plate as air is compressed from or drawn into the cylinder.
In another known reed valve configuration, a reed valve lies freely over a port in a valve plate and a curved valve stop surface in the head lies above the reed to stop it when air blows through the port. In these devices, the head is separated from the valve plate by a gasket and the ends of the reed valve are prone to chew away at the gasket, work their way into the gap between head and plate, and become pinched. Further compressor operation flexes the reed around its "pinch point" and between the head and plate, and the reed can prematurely fail, severely reducing compressor reliability. Another disadvantage of this construction is that fluttering valve ends can cut grooves in the head stop surfaces. The reed can work itself into these wear grooves and find itself then locked in the wear zone it has cut out, in an open position spaced away from its associated port.
In another type of known device, a reed is positioned over a raised port in a valve plate, and an integral, concave stop bar is disposed on the valve plate over the reed. The stop bar, at its ends, captures the flexible reed over the raised port and may or may not touch the reed when it is closed. Air pressure in the port flexes the reed open. Such stop bar configuration, because of its shape, is difficult and expensive to use where it must be hardened. It also requires separate fasteners which lead to assembly difficulties.
Moreover, it is believed that compressors of the type noted, i.e., two-stage, twin-cylinder compressors of about 5 horsepower, for example, are generally run at about 900-1000 rpm, or less, by a belt and pulley drive, for example, and produces about 16.5 cfm at 175 psi. It is desirable, however, to provide a compressor of much more compact and lighter construction, while retaining a similar output. While it may be possible to retain such similar output in a smaller compressor operating at higher speeds, it has been found that valve structures such as the reed valves mentioned above, which function sufficiently at lesser speeds, cannot handle such higher speeds. When run at higher speeds, such valves produce less efficient results, fail prematurely, or both. Thus, the selection of a valve structure for a compressor having an increased output is considerably complicated by the inherent disadvantages of the prior structures noted above, or by their inability to efficiently handle increased operating speeds, or both.
It has accordingly been one objective of this invention to provide an improved reed valve for an air compressor.
A further objective of the invention has been to provide an improved valve plate and valves for use with an expansible chamber and head.
A further objective has been to provide an efficient, long-lasting reed valve for a compact, twin cylinder, two-stage air compressor operating at about 1725 rpm and producing about 16.5 cfm at about 175 psi.
One consideration in the manufacture of piston type air compressors is the construction of the crankshaft, which must be dynamically balanced, and the simultaneous desirability of using a one-piece piston connecting rod.
In order to most optimally dynamically balance a crankshaft used in a V-twin compressor, it is generally necessary to provide a crankshaft with counterweights at each end thereof. This necessitates, however, the use of two-piece connecting rods since it is generally not possible to slip such a double weighted crankshaft through a one-piece connecting rod for assembly. Use of a two-piece connecting rod increases the possibility of a loose screw or other part in the crankcase, failure of the connecting rods, or both. This can severely reduce reliability.
Accordingly, it has been a further objective of the invention to provide an improved crankshaft for a compressor, which can be dynamically balanced with counterweights at both ends, yet can be used with one-piece piston connecting rods.
Where it is desired to provide a direct drive compressor, the coupling between the motor drive shaft and the compressor crankshaft can be the source of several problems. In one configuration, as an example of one problem, the motor drive shaft is screwed into the crankshaft. Through time and many operational cycles, the drive shaft and crankshaft interact to produce "fretting" corrosion. This makes it extremely difficult to separate the two parts for maintenance or parts replacement.
Accordingly, it has been one objective of the invention to provide an improved crankshaft and for preventing fretting or corrosion between the crankshaft and a motor drive shaft.
Moreover, where a cooling fan is to be used in conjunction with the compressor, means to mount and drive the fan must also be considered.
In a typical belt driven compressor, a driven pulley serves dual purpose. It provides a speed reducer, its spokes operate as a cooling fan. Where a direct drive motor and compressor configuration is to be utilized, in lieu of a belt drive and fan pulley, the compressor crankshaft can also be used to drive a cooling fan.
In this regard, it has been a further objective of the invention to provide an improved cooling fan drive for a direct drive compressor.
It has been a further objective of the invention to provide an improved cooling fan drive in a direct drive air compressor together with an improved compressor crankshaft.
It has been a still further objective of the invention to provide an improved direct drive compressor crankshaft for preventing fretting or corrosion between the crankshaft and a drive shaft, which can be dynamically balanced by means of counterweights on opposite sides of a one-piece piston connecting rod and which provides an improved direct drive fan or cooling fan.
When a fan is used with a compressor for cooling, it is desirable to maximize its cooling efficiency. Air directing shrouds have been used for this purpose. It has been, however, a further objective of this invention to provide an improved fan shroud and compressor wherein cooling air is even more efficiently handled.
Air compressors frequently utilize intake manifolds for the purpose of both filtering air or for muffling the noise generated by the compressor. The combination of elements to provide both appropriate filtering and desirable muffling performance is frequently elusive.
Accordingly, it has been a further objective to provide an improved intake manifold for both filtering incoming air to be compressed and for muffling compressor noise.
To these ends a preferred embodiment of the invention includes an improved valve and valve plate for use between the cylinder and cylinder head of a compressor. The valve plate is provided with at least one free-floating reed valve therein. The new reed valve is not held, pinched or biased into any particular position, but is free to float between a closed position over an exhaust port, for example, in the plate, and an open position where portions of its end areas engage respective hardened and radiused keeper bars lying transversely over the reed. There is more vertical space between the keeper bars at the floor of the reed valve recess on the valve plate than the reed is thick, thereby providing its free-floating condition.
Since the keeper bars are relatively small and constitute parts which are not an integral part of the head, the valve plate or any restrictor plate, they can be easily hardened and thus eliminate the necessity and expense of hardening the much larger head or valve plate, for example.
The keeper bars lie in recesses which are shallower than the thickness of the bars. Thus, the bars extend above the surface of the valve plate. The head is provided with keeper bar engaging surfaces and a concave reed stop surface contoured to receive the opening reed, and grooved to permit air to cross over the reed to the exhaust port from the head.
An elongated silicone seal is disposed preferably in a groove extending peripherally around the head and seals against the valve plate, when the head is assembled to the valve plate, once the keeper bar engaging surfaces engage the keeper bar. These surfaces are in the same general plane as other head surfaces mating with the valve plate and may not touch, except at the points where the head bolts are located. Nevertheless, the seal effectively seals the head and valve plate together once the head engages the keeper bars.
On the intake side, the valve plate is provided with an intake valve recess receiving a free-floating reed valve similar to that of the exhaust side. This intake valve is similarly captured, in a free-floating condition, by hardened and radiused keeper bars lying in channels and transversely spaced over the reed.
A restrictor plate recess is also provided in the intake side, and a ported restrictor plate is disposed therein for securing the keeper bars over the intake reed and serving as a reed stop. The restrictor plate has a portion extending beyond the open cylinder bore below it so as to itself be held in place by surfaces surrounding the cylinder at its upper end.
As in the exhaust side, the intake reed keeper bars are thicker than their receiving channels are deep. The restrictor plate has surfaces engaging these bars before the restrictor plate bottoms out in its recess. The engagement of the restrictor plate by the upper cylinder surfaces thus retains the keeper bars in proper position, capturing the intake reed in its recess in operative relationship with an intake port in the valve plate.
An elongated silicone seal is disposed in a groove in the intake side of the valve plate. This seal engages surfaces on the upper end of the cylinder and seals the valve plate and cylinder when the plate is assembled thereover and the restrictor plate is bottomed on the keeper bars.
The valve plate and valves so described are capable of operating at high speed cycles of, for example, 1725 compressions per minute. The free-floating valves are not pinched, and not required to flex along a fixed "hinge line," but rather free float and provide a lengthy service life even at the noted high speed operation. The valves are very easy to replace, and there are no rivets or screws to remove, or to fall into the cylinder.
In another aspect of the invention, an improved compressor crankshaft is cored or hollowed out, and has an integral counterweight provided at a driven end thereof. For direct drive, the crankshaft drive end is bored out and threaded to receive the drive shaft of a motor. According to a preferred embodiment of the invention, the bore of the drive end of the crankshaft extends through said crankshaft to the hollowed out area. This area is opened, through large portals in the crankshaft within the crankcase, and oil from the crankcase is transmitted to the internal threaded area connecting the crankshaft with the drive shaft. This lubricates the threaded drive connection and prevents fretting or corrosion.
The cored crankshaft is preferably provided with an integral counterweight on its driven end, but no integral counterweight on the other end. This other end can easily be slipped into a one-piece piston connecting rod. A removable counterweight is disposed on this same other end, after connecting rod assembly. Thus, the crankshaft can be balanced through the use of counterweights on two ends, yet still accommodates a one-piece connecting rod.
A fan is mounted on the drive axis provided by the end of the crankshaft to which the removable balance counterweight is mounted. According to the invention, a fan drive pin extends from the removable counterweight at a position radially spaced from the drive axis and engages the fan to drive it as the crankshaft and counterweight rotate. This provides a positive fan drive through the nevertheless removable counterweight.
In another aspect of the invention, a shroud is provided to direct air into and from the fan over the cylinders and cylinder heads in a V-shaped configuration. Deflectors are provided in conjunction with air exhaust ports mounted in shroud projections of a V-shaped shroud backplate to direct cooling air over the heads and cylinders.
An intercooler provides a compressed air passage leading from one cylinder to the other, i.e., from the first to the second stage. The intercooler is in a wound or spiral configuration and is disposed behind the shroud backplate. An orifice is disposed in the backplate, between the cylinder cooling exhausts, and is in register with the intercooler to direct cooling air over it and cool the first stage air as it moves into the second stage.
In still another aspect of the invention, an intake manifold comprises a chamber defined by a shroud and a backing plate. The chamber is divided into two portions by two sets of ribs extending from the backing plate to the shroud. The sets of ribs define between them a slot for receiving a foam type air filter. Opposed walls mounted on elongated edges of the ribs close off the chamber portions from each other, excepting an air passageway between the forward wall edges spaced from, but near, the shroud side of the chamber.
A plurality of open air inlet tubes extend into a first chamber portion from said shroud to a position spaced from but proximate to the backing plate. An air outlet port is disposed in the second chamber portion for conducting filtered air to the first stage of the compressor. The combination of the tubes and the chamber portions serve to efficiently muffle compressor noise.
These and other objectives and advantages will become readily apparent from the following written description of the invention and from the drawings in which:
US Referenced Citations (24)
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 0595221 |
Mar 1925 |
FRX |
Divisions (2)
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Number |
Date |
Country |
| Parent |
252695 |
Oct 1988 |
|
| Parent |
856645 |
Apr 1986 |
|
Patent Grant
5020973
