FIELD
This present disclosure relates to the field of automotive heating ventilation and air conditioning (HVAC) variable displacement compressors and the assembly thereof.
BACKGROUND
This section provides background information related to the present disclosure which is not necessarily prior art.
The present teachings relate to automobiles and automotive Heating Ventilating and Air Conditioning (HVAC) systems. Air Conditioning systems generally include a compressor or air conditioning (A/C) compressor or pump to distribute a refrigerant throughout the system. The present teachings relate to a variable type compressor and assembly thereof.
SUMMARY
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A variable displacement compressor may comprise a front housing, cylinder housing and rear housing. There may also be a rotary shaft that may have a first end and a second end. The first end of the rotary shaft may be disposed through the front housing. The second end of the rotary shaft may be disposed through the cylinder block. The second end of the rotary shaft may have a reduced diameter portion and may also have a shoulder portion. A stopper may be inserted over the reduced diameter portion and may abut the shoulder portion of the rotary shaft.
Another aspect of the disclosure may be a variable A/C compressor that may have a front housing that may form a crank chamber. The compressor may also have a plurality of cylinder bores formed in the cylinder housing. The compressor may also have a shaft that may have a first end rotatably supported by the front housing and a second end that extends through the cylinder housing. Additionally the valve plate may be located at an opposite side of cylinder housing from the crank chamber. A selected size stopper may be press fitted over the second end of the shaft and abut a shoulder on the shaft.
Yet another aspect of the present disclosure may be the method of assembly of the variable displacement compressor. The method may have the step of inserting the first end of the shaft through the front housing. Another step may be inserting the second end of the shaft through the cylinder housing. The assembly method may then measure the distance between the shoulder of the second end of the shaft and the rear surfaces of the cylinder housing. The method then may then select a ranked stopper from an inventory of sorted and ranked by varying lengths of the stopper. The method then may press the ranked stopper onto the second end of the shaft until the stopper abuts the shoulder of the shaft.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
DRAWINGS
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
FIG. 1 is a schematic representation of a vehicle having a HVAC system.
FIG. 2 is diagram of a HVAC system.
FIG. 3 is a cross section view of a variable A/C compressor
FIG. 4 is a exploded view of the second end of the shaft of the variable A/C compressor.
FIG. 5A is a cross section view a compressor during assembly.
FIG. 5B is a cross section view a compressor during assembly.
FIG. 6A is a isometric view of a stopper.
FIG. 6B is a plane view of a stopper.
FIG. 6C is a isometric view of an alternative embodiment stopper.
FIG. 6D is a plane view of an alternative embodiment stopper.
FIG. 7A is a cross section view a compressor during assembly.
FIG. 7B is a cross section view a compressor during assembly.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
DETAILED DESCRIPTION
Example embodiments will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
Referring initially to FIG. 1, a vehicle 10 includes an engine compartment 12 and a HVAC system 14, depicted in dotted lines. HVAC system 14 may include an air-conditioning compressor 16 in the engine compartment 12, an HVAC unit 18, that heats or cools the passenger compartment 20. Turning now to FIG. 2, which represents a simple schematic diagram of a HVAC system 14 will be further explained. A refrigeration cycle of HVAC system 14 includes compressor 16 which draws, compresses, and discharges a refrigerant, such as R134a, 1234YF, CO2, by way of non-limiting example. The power of a vehicle engine 22 may be transmitted to compressor 16 through a pulley 24 and a belt 26 to enable compressor 16 to compress the refrigerant.
In HVAC system 14, the compressor 16 discharges a superheated gas refrigerant at a high pressure, which flows into a condenser 28, where heat exchange is performed with outside (ambient) air that flows across the condenser represented by arrow 30. The ambient air may be forced by a cooling fan (not shown). The refrigerant is cooled before and during condensation. The refrigerant is condensed in condenser 28 and may flow into a receiver 32. Those skilled in the art will recognize that the HVAC system 14 may be an accumulator or an expansion valve 34 system. The current description is of a T×V system, however the principles taught in this disclosure may be for either system.
The liquid refrigerant from the receiver 32 is expanded by an expansion valve 34, also known as a thermal expansion valve or TXV, into a gas-liquid double phase state of low pressure refrigerant fluid. The low pressure refrigerant from TXV 34 flows into an evaporator 36 by way of an inlet pipe 38. Evaporator 36 is arranged inside HVAC unit 18 of the HVAC system 14. The low pressure refrigerant flowing into evaporator 36 absorbs heat from the air 40 inside the HVAC unit 18 as air 40 is passed over evaporator 36. Outlet pipe 42 of evaporator 36 may be connected to the suction side of compressor 16, so that the refrigeration cycle components mentioned above constitute a closed fluid circuit.
HVAC unit 18 forms a ventilation duct through which air conditioning air is sent into passenger compartment 20. HVAC unit 18 may contain a fan 44 that is arranged on the upstream side of the evaporator 36. An fresh or recirculation air switch housing (not shown) may be arranged on the suction side of fan 44, that is, the left side of fan 44 in FIG. 2, such that the air inside passenger compartment 20 (inside air) or the air outside passenger compartment 20 (outside air) may be alternated or mixed and introduced through fresh or recirculation air switch housing and into the HVAC unit 18 by fan 44.
HVAC unit 18 accommodates, on the downstream side of evaporator 36, a hot water heater core (heat exchanger) 46, which has an inlet pipe 48 and an outlet pipe 50. Hot water (coolant) of vehicle engine 22 is directed to heater core 46 through inlet pipe 48 by water pump 52. A radiator 54 and a thermostat 52 further cooperate to control the temperature of the circulating liquid coolant.
Disposed inside the HVAC unit 18 is an air mix door 56 that adjusts the volume of air that passes through or bypasses the hot water heater core 46. Additionally, a plurality of outlets 58 are formed at the downstream end of the HVAC unit 18, the outlets 58 may be configured to direct air to different areas of the passenger compartment 20. Outlets 58 may be opened and closed by outlet mode doors (not shown).
With reference now to FIG. 3, compressor 16 is depicted in a cross-sectional view, the current teachings are in regards to a variable displacement compressor. Compressor 16 has a front housing 60, a cylinder housing 62 also known as a cylinder block, and a rear housing 64, which all may be joined together by a plurality of bolts 66, for example. The bolts 66 are inserted through the front housing 60 and cylinder housing 62 and are threaded into the rear housing 64 to hold the assembly together. A shaft 68, also known as a rotary shaft, is centered in the front housing 60 and passes through the cylinder housing 62. The front housing 60 forms an enclosure known as a crank chamber 70. Within the crank chamber 70 a lug plate 72 is attached to the shaft 68. The lug plate 72 is supported against the front housing 60 by a thrust bearing 74, the lug plate 72 and thrust bearing supports the shaft 68 in a front axial direction. A generally disk-shaped swash plate 76 is loosely or pivotably installed around shaft 68 so as to be able to freely tilt or pivot with respect to the shaft 68, while also contacting shaft 68. The shaft 68 and swash plate 76 may freely rotate within crank chamber 70 and may cause one or more pistons 78 to reciprocate parallel to shaft 68 within the cylinders 80, also may be known as cylinder bores, of the cylinder housing 62. As an example seven pistons 78 may be provided at equal or unequal intervals around the shaft 68, it is also known in the art that variable displacement compressors may have five or six pistons.
Continuing with FIG. 3, a plurality of semispherical shoes 82 may fit into a pair corresponding semispherical recesses that oppose one another. The recesses are formed in the end of each piston 78 and facilitate movement of each piston 78 with a corresponding periphery of swash plate 76. Alternatively, each semispherical shoe 82 may have flat surfaces that abut the flat surface of the swash plate 76. An arm 84 may be attached to and project out and away from lug plate 72. Swash plate 76 also has a corresponding arm that further projects out to arm 84 with an arm-like guide 86. The compressor 16 also has a working chamber 88, also known has a compression chamber that is formed by a flat surface or face 90 of piston 78, cylinders 80, and valve plate 92. The working chamber 88 is for compressing a fluid, such as a refrigerant for an air-conditioning system. A control valve 94 is located in the rear housing 64. The control valve 94 regulates the angle of the swash plate 76 buy controlling the pressure of the crank chamber 70. When pressure in the crank chamber 70 is reduced the swash plate 76 angle increases and lengthens the stroke of the pistons 78, thus increasing the displacement, increasing the volume of the working chamber 88, of the compressor 16. The rear housing may also have a suction port 96 which is connected to the outlet pipe 42 of the evaporator to allow refrigerant to flow into the compressor 16. The suction port is fluidly coupled to the suction chamber 98 enclosed in the rear housing 64. The suction port 96 fluidly communicates with working chamber 88 through a series of one way valves (not shown). Discharge port 100 also is in fluid communication with working chamber 88 through a series of one way discharge valves (not shown).
Further continuing with FIG. 3 the shaft 68, which has a first end 101 that is exposed outside the front housing 60 to attach a pulley 24 (FIG. 2), and a second end 103 that abuts a selectable stopper 102 to prevent axial movement of the shaft 68 toward the rear housing 64. The stopper 102 may abut against the valve plate 92 and may act as a bearing for the rear of the shaft 68 during operation of the compressor 16. FIG. 4 is an exploded view of dotted circle A of FIG. 3. The shaft has a shoulder 104, or a step, machined or formed into the end of the shaft 68, creating a reduced diameter portion 105 of the shaft, the shoulder 104 may also be referred to as shoulder portion 104. The stopper 102 abuts the shoulder 104 to prevent any movement relative to the stopper 102 and shaft 68. During operation of the compressor 16 the stopper 102 generally may contact the valve plate 92. However during assembly, it is recommended that the dimension D to be maintained at a range 30-90 microns (μ). This generally allows for enough stack-up tolerance to prevent the pistons 78 from crashing into the valve plate 92 during operation. However, it is not to much clearance as to reduce the efficiency of the compressor 16 overall by causing too much top clearance, which is the distance from the piston face 90 and the valve plate 92 at full compression. To control dimension D to such a tight tolerance the stopper 102 can be selected from a series of length ranked stoppers 102 during the assembly process that will be described in the forgoing description.
The present disclosure discusses the selection process of a ranked or selectable stopper 102. FIG. 5A displays the compressor 16 in a state of assembly. The compressor 16 sits in an assembly nest 106; the assembly nest has a controlled surface 108 in which a controlled machine surface 110 of the front housing 60, shown in FIG. 3, rests upon. The assembly nest 106 may be connected to an assembly conveyor (not shown) to move it to different assembly stations. Measuring tool 112 makes contact with the shoulder 104 of the shaft 68. FIG. 5B displays measuring tool 112 making contact with the rear surface 114 of the cylinder housing 62, rear surface 114 abuts the valve plate 92 when the compressor 16 is fully assembled. Both measurements may be done at separate stations during assembly or at the same station. The measurements are received by a computer (not shown) on the assembly line and the computer determines the stack up dimension from the shoulder 104 of the shaft 68 and the rear surface 114 of the cylinder housing 62. The computer than can select or indicate which length stopper 102 can be installed on the shaft 68 to maintain the recommended dimension D at a range 30-90 microns (μ).
FIGS. 6A-6D displays multiple embodiments of the stopper 102. Generally the stopper may contain an opening 116 where the reduced diameter portion 105 of the shaft 68 is inserted during assembly. The opening 116 may be press fit onto the reduced diameter portion 105 to prevent movement between the shaft 68 and stopper 102. The stopper 102 may also contain a flange portion 118, the flange portion provides a surface 120 to contact the valve plate 92 (FIG. 3) during operation of the compressor 16. Additionally, the stopper 102 may have holes (not shown) in the body 122 portion or the flange portion 118. For assembly of the compressor 16, the length dimension X is used to maintain the recommended dimension D at a range 30-90 microns (μ). The stopper 102 is manufactured at several different lengths X. The lengths can vary and may be ranked by length, for instance based on the stack up tolerance of the compressor 16; the stopper 102 length may need to vary by 10-20 microns (μ) and the assembly process may choose between, for example, five ranked stoppers giving a total range difference of one hundred microns (μ). If the computer (not shown) on the assembly line (not shown) measures a large distance between the shaft shoulder 104 and the rear surface 114 of the cylinder housing 62, then it would select a larger ranked stopper 102, however if a small distance is measured, then a stopper 102 with a smaller length dimension X will be selected. The length and the ranking of the stopper 102 is dependent on the tolerances of the other components in the compressor 16, it can be appreciated that if the tolerances on the other components are greatly varied then a larger length dimension range may be needed for the stopper 102. The stopper 102 may be manufactured by for example, stamping into shape a cold rolled steel or stainless steel, then sorted into the various lengths X. The stopper 102 needs to be formed from a strong enough material to maintain the dimension D during operation.
Once the proper length stopper 102 is selected with the proper length X. An operator or machine (not shown) may place it on the end of the shaft 68, as shown in FIG. 7A. A press 124 will make contact with the stopper 102 and press it down axially until the stopper 102 abuts the shaft shoulder 104 as shown in FIG. 7B. The reduced diameter portion 105 and opening 116 create a press fit. The rest of the compressor 16 may be further assembled.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.
Patent Application
20170067457
