COMPRESS CONTROL OF FIRE FIELD OF THE INVENTION The present invention relates, in general terms, to the control of an air compressor in an internal combustion engine, and more particularly, to the control of the activation and deactivation of an air compressor with based on the temperature of the compressed air. BACKGROUND TO THE INVENTION Modern trucks contain air compressors that are used to charge an air tank from which air-powered systems, such as service brakes, windshield wipers, air suspension, etc., can be powered in air. In a typical truck application, an air compressor can operate in a charged or activated state for a large part of the time. Systems have been developed to reduce the amount of time during which the compressor is in the activated state. For example, systems have been developed that activate the compressor when the pressure in a reservoir drops below a first predetermined value, and deactivate the compressor when the pressure in the reservoir reaches a second higher predetermined value. U.S. Patent No. 6,036,449 to Nishar et al. discloses an air compressor control that monitors the pressure in the tank and the head metal temperature
of the compressor. When the tank is at a pressure between two set pressures and is in a charged state, the air compressor will be discharged after a set time interval that is based on a compressor head metal temperature to maintain metal threshold temperatures. of compressor head within a suitable range. Additionally, the compressor head is evaluated such that when the compressor head temperature exceeds a predetermined threshold temperature, the air compressor is placed in a non-activated state until the compressor head temperature falls below a temperature default threshold. The temperature of the head metal is controlled in order to avoid excessive heating of the head. COMPENDIUM OF THE INVENTION The present invention relates to the control of air compressors based on the temperature of the compressed air by the air compressor. In a method for controlling an air compressor, a temperature of compressed air is detected by the air compressor. The detected compressed air temperature is compared to a predetermined threshold temperature. The air compressor is deactivated when the detected temperature exceeds the threshold temperature. In one embodiment, the air compressor is deactivated when the detected temperature exceeds the threshold temperature and a
Detected reservoir pressure is above the threshold pressure. In one embodiment, the threshold temperature is selected to inhibit the carbon oxidation by oil decomposition. The temperature of the compressed air can be detected in several locations. For example, the temperature of the compressed air can be detected in a compressor port, such as an exhaust port, or a discharger valve port. The temperature of the compressed air can be detected in a compression chamber. In one embodiment, the temperature of the compressed air is sensed by a temperature sensor mounted on a compressor unloader valve that is in fluid communication with a compression chamber. An air compressor adapted for control based on a temperature of the compressed air includes a frame, a head, a piston, and a temperature sensor. The head is mounted on the frame in such a way that the head and frame define a compression bed and a fluid passage in communication with the compression chamber. The piston is placed in the compression chamber to compress air in the compression chamber. The temperature sensor is positioned to measure an air temperature compressed by the piston. In one embodiment, the temperature sensor is substantially insulated from the head and the frame.
An air compressor controller includes an input, a memory, a processor, and an output. The input receives compressor air temperature signals. The memory stores a compressor control algorithm. The processor applies the compressor control algorithm to the compressor air temperature signals. The processor provides an air compressor deactivation signal when the compressor air temperature signal exceeds the threshold temperature signal value. The output communicates the compressor deactivation signal to selectively deactivate a compressed air compressor. Alternatively, the controller may consist of discrete electronic components without processor or memory. For example, the controller could comprise an integrated circuit of temperature components for converting input signals into voltages and a voltage comparator component could control the output based on voltage thresholds. A vehicle air supply system includes a tank, an air compressor, a temperature sensor and a controller. The tank stores compressed air provided by the compressor. The temperature sensor is positioned to detect a temperature of the compressed air. The controller is attached to the compressor. The controller compares a detected temperature of the compressed air by the air compressor with a predetermined threshold temperature and
deactivates the air compressor when the detected temperature exceeds the threshold temperature. In one embodiment, the controller activates the compressor when an air pressure in the reservoir is lower than a predetermined threshold pressure and the detected temperature exceeds the threshold temperature. Additional advantages and benefits will be apparent to those skilled in the art after taking into account the following description and the appended claims in combination with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of an air supply system of a vehicle; Figure 2 is a flow diagram illustrating a method for controlling an air compressor based on a temperature of compressed air; Figure 3 is a schematic illustration of a vehicle air supply system; Figure 4 is a flow chart illustrating a method for controlling an air compressor based on a compressed air temperature and a reservoir pressure; Figure 5 is a schematic illustration of a compressor controller; Figure 5a is a schematic illustration of a compressor controller; Figure 6 is a schematic illustration of a compressor; Y
Figure 7 is an illustration of a discharging valve. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the control of the activation and deactivation of a scroll compressor based on the temperature of the pressed compressor. The present invention can be implemented in various forms of different vehicle air supply systems. Figure 1 illustrates an example of said vehicle air supply system 12. The illustrated air supply system 12 includes an air compressor 10, a reservoir 16, a regulator 18, and an air dryer 20. The compressor of air 10 includes a frame 11, a head 13, and a piston 15. The head 13 is mounted on the frame 11 in such a way that the head and the frame define a compression chamber 17. The piston 15 moves in a reciprocating manner in the compression chamber 17 to compress air in the compression chamber in a known manner. The compressor 10 can be driven by a vehicle crankshaft (not shown). The compressor 10 receives air from an air source 22, such as an engine air intake. The compressor 10 compresses the air and provides the compressed air to the reservoir 16. In the air system illustrated in Figure 1, the regulator 18 places the compressor 10 in an activated or charged state when the pressure in the reservoir 10 falls below a minimum pressure
default and places the compressor in a deactivated or discharged state when the pressure in the reservoir reaches a predetermined maximum pressure. In the example illustrated by Figure 1, the regulator 18 places the compressor 10 in a discharged state by providing an air signal to a compressor unloader 24. The compressor unloader can take different forms. For example, the discharger 24 may be a mechanism that holds open an inlet valve 25, or it may be a separate valve assembly 54 (as shown in Figures 6 and 7).
Figure 2 illustrates a method for controlling the air compressor 10 based on an air temperature compressed by the air compressor. A temperature TA of compressed air by the air compressor is detected 30. The temperature TA of detected compressed air is compared 32 with a predetermined threshold temperature TH. If the detected air temperature TA is greater than the predetermined threshold temperature TH, the compressor is deactivated 34 or discharged. If the detected air temperature TA is lower than the predetermined threshold temperature TH, activation 36 or load of the compressor is allowed. In an exemplary embodiment, the compressor 10 is lubricated through oil. For example, the compressor 10 can be lubricated with engine oil that drives the compressor. When the engine oil becomes excessively hot,
the oil can decompose and carbon can be formed. Carbon formation can damage the compressor and / or plug lines 37 in the air supply system, such as a line between compressor 10 and tank 16. In one embodiment, the predetermined threshold temperature TH is set to avoid the formation of carbon. In one example, the predetermined threshold temperature of the compressed air can be adjusted within the range of 163 to 204 degrees Celsius (325 to 400 degrees Fahrenheit) as measured at the compressor outlet passage. For example, the predetermined threshold temperature T, could be set to 190 degrees Celsius (375 degrees Fahrenheii) as measured at the compressor exit passage 46. In one embodiment, the compiler = maintained in the deactivated state until the air temperature detected ba e below a temperature T ^ of the predetermined lower limit. The difference between the threshold temperature TH and the temperature of the inner limit TL prevents the compressor from being subjected to rapid cycles between activated and deactivated states. In an embodiment, the activation of the compressor is allowed as soon as the detected compressed air temperature TA is below the upper control temperature TH. Figure 3 illustrates a compressor control circuit 40 which controls a compressor 10 in a power supply system.
air 12 based on a temperature of compressed air. The illustrated control circuit 40 includes a controller 42, a temperature sensor 44, and a control valve 47. The temperature sensor 44 is positioned to sense the temperature of the compressed air. The temperature sensor 44 can be placed in several positions to detect the temperature of compressed air supplied by the compressor. In the embodiment illustrated in Figure 3, the temperature sensor 44 is positioned in the compressor outlet passage 46 to measure the temperature of the compressed air at the outlet port. Additional examples of locations for the temperature sensor include the compression chamber, 17, an exhaust port 50, a line 37 connecting the compressor 10 to the reservoir 16, and a discharging valve 54 (Figure 6). In the exemplary embodiment, the temperature sensor 44 is positioned in such a way that the temperature sensor is substantially isolated from structures with significant masses, such as for example the head 13 and the frame 11. The fact of substantially isolating the temperature sensor 44 of the head 13 and of the frame 11 provides a more accurate measurement of the temperature of the compressed air. If the temperature sensor is thermally connected to the head 13 or to the frame 11, the temperature sensor 44 will detect the temperature of the head or of the
frame, instead of detecting the temperature of the compressed air. The temperature of the compressed air can not be correlated with accuracy from the temperature of the head 13 or of the frame 11. The head 13 and the frame 11 have a large thermal mass that is heated or cooled in a considerable period of time, As a result, there is a significant delay in head or frame temperature changes due to changes in the temperature of the compressed air. In addition, the head and frame are typically cooled by the engine cooling system. The engine cooling system typically operates to control the temperature of the engine regardless of the temperature of the compressed air. As a result, the head or head temperature controlled by the engine cooling system is independent of the temperature of the compressed air. Accordingly, an accurate estimate of the temperature of the compressed air can not be obtained by measuring the temperature of the head 13 or of the frame 11. The temperature sensor 14 detects a temperature of the compressed air and provides a signal which is an indication of the temperature sensed to the controller 42. With reference to Figure 3, the illustrated control valve 47 includes an inlet 54 connected to the tank 16 and an outlet connected to the unloader 2. The controller 42
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controls the control valve 47 to selectively communicate an air signal from the reservoir 16 to the unloader to selectively deactivate the compressor 10. For example, the controller can open the control valve to provide the air signal to the unloader when the detected temperature exceeds a predetermined threshold temperature TH to place the compressor in an unloaded state. The controller can close the control valve when the detected temperature is below the predetermined threshold temperature to allow the compressor to be placed in an unloaded state. In one embodiment, the control valve is a solenoid controlled valve. In the illustrated embodiment, the path from the reservoir 16, through the control valve 47, to the discharger 24 is parallel to the path from the reservoir 16, through the regulator 18, to the discharger. As a result, the control valve 46 can operate to bypass the regulator 18 and deactivate the compressor 10 when the sensed compressed air temperature exceeds the predetermined threshold temperature ba or control of the controller 42. In one embodiment, the air compressor 10 is activated when an air pressure PR is from the electrode 16 is lower than a predetermined minimum pressure PL and the detected temperature TA exceeds the threshold temperature Tμ. In the example illustrated by
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Figure 3, a GO pressure detector detects the pressure in the reservoir 16. The gas detector provides a signal to the controller 42. In this mode, the controller 42 deactivates the compressor 10 when the temperature of the compressed air is above the the predetermined threshold temperature and the reservoir pressure is above the predetermined minimum pressure. In this mode, the controller 42 does not deactivate the compressor 10 when the compressed air temperature TA is above the predetermined threshold temperature TH and the reservoir pressure PR is below the predetermined minimum pressure. This prevents the pressure in the tank from falling below the predetermined minimum pressure PL. This predetermined minimum pressure set by the controller 42 may be different from the predetermined minimum pressure set by the regulator 18. Figure 4 illustrates a method for controlling an air compressor based on a compressed air temperature and a reservoir pressure. In the method illustrated by Figure 4, upper and lower compressor control temperatures TH, TL and upper and lower tank pressures PH, PL are set 70. For example, compressor control temperatures and pressures can be read from the memory. In the example mode, the upper compressor control temperature TH is selected to avoid the formation
of carbon and the lower control temperature TL corresponds to an acceptable compressed air temperature. For example, the upper and lower control temperatures TH, T can be 190 degrees Celsius (375 degrees Fahrenheit) and 163 degrees Celsius (325 degrees Fahrenheit), respectively, as measured at an output 46 of the air compressor 10. The pressure The upper control PH can correspond to a higher safe operating pressure of the reservoir and the lower control pressure temperature PL can be selected to ensure that there is sufficient air in the reservoir to operate the air driven systems. In a modality, the state (activated or deactivated) is determined or established starts 1 mind. The compressor 10 may initially be set 72 in the activated state After setting the initial temperature and pressure control values, a compressor control loop 74 is repeated each time a predetermined time lapse passes. compressor control, the temperature of the compressed air by the air compressor is detected 76. The pressure of the compressed air in the tank is detected 78. The detected temperature is compared 80 with the upper control temperature TH and the detected pressure is compared 82 , 83 with the lower control pressure P-_. The air compressor is activated 84, 85 when the pressure measured is lower than the lower control pressure PL ndependently of the
detected temperature. The comp. e cp e air is deactivated 86 when the temperature detects a? i-hasa the upper control temperature TH and the affected pressure is higher than the lower control pressure P ^. When the temperature TA is lower than the upper control temperature TH and the pressure PR is greater than the pressure of conrro-, lower PL, the pressure PR is compared with the upper control pressure PH. If the PR pressure is greater than the pres > "If the pressure PR is lower than the upper control pressure PH, the compressor is kept in its current state ot ted or deactivated." The control loop is repeated pa.a Jiitrolar the activation and deactivation of the controller.In a mode, the method illustrated by Figure 4 is effected by a regulator and an electronic controller.In another mode, the method illustrated in Figure 4 is effected through a controller that In this modality, the regulator can be eliminated In a modality of the method shown in Figure 4, once the compressor is deactivated, activation is delayed. in order to avoid cycles _ap? d? s between the activated state and the state desat.t_ / a *. ' For example, if the compressor is deactivated due to the high compressed air temperature detected, the compressor bypass
it can be delayed until the detected pressure reaches the lower control temperature, even when the detected compressed air temperature may have fallen below the intrinsic control temperature T. Figure 5 is a pictorial illustration of a controller 42 that can be used to coerce the compressor based on a temperature of the compressor. For example, the controller could jti. to perform the methods illustrated through Figures 2 and 4. In a controller 42 illustrated in the PJ emolo of Figure 5 includes an input 90, memory 92, a processor 94, and an output 96. The input 90 receives ^ psi compressor air temperature 98 and / or deposit signals e -.n. 100. Memory 92 stores an algcr.p-compressor control and predetermined values e.g. higher control temperature values * mferror and / or Higher and lower pressure values.
of the compressor control algorithm are illustrated in FIGS. 2 and 4. The processor 94 applies the compressor control algorithm to the compressor temperature signals d ^ - * re and / or tank pressure signals with The output signals 102 are output from the output of controller 96 to the control valve (FIG. 3). Examples of balance signals 1 include a signal from
compressor activation of a i * -) -.- ui ovo that the compressor can be activated and a signal e - ^ activation of air compressor that causes the
~ > It can be deactivated. Figure 5a illustrates another and emp_. a controller 42 '. The controller 42 'includes a * -tr i 103 from a thermocouple or other temperature measuring device, a voltage convector component 105, an input 104 from a pressure gauge or other L '^ n measuring device and a pressure converter component at te.s_-c> Input 103 receives air temperature signals from compressor 98. Input 104 receives pressure signals from site 100. The The temperature converter component in voltage 105 converts the temperature signals from A to Z, O to voltage signals 109. The component cf N 'pressure in voltage 106 converts the SPUs. deposited in voltage signals 110. The voltage transformer 107 provides an output signal when the voltage signals supplied to the voltage source by the voltage converters are within the threshold limits. With references to the Figures \ ~, in a to mode, the temperature of the compressed air DUI the air compressor 10 is detected by a sensor 44 mounted on a valve assembly of 1e-t ^ lo 54 which is in
Fluid communication with the compression chamber 17. The valve assembly ele desires: j 1 illustrated 54 includes a stationary member 112, a movable m.emb1 114, and a thrust member 116, such as by a pl ". The thrust member 116 pushes the member 114 away from the stationary member and in engagement with a valve seat 118. When the mobile member 114 is in engagement with the valve seat 118, in the case of the unloader 120 through the head 13 is closed and the compressor 10 is in an activated state.An air control signal is selectively communicated to control port 120 of the discharger valve assembly 74 through the regulator and / or of the control valve 4C. '' When the air control signal is applied to the assembly? e '- - Discharge valve, the movable member 114 is released to the - no gripping with the valve seat by the control signal Je air against the force applied by the member When the mobile member 114 is not in engagement with the valve seat 118, the discharger passage 120 is in the open state and the compressor 10 is in a steady state.
In the example of Figure 7, -1 movable leg 114 includes an opening 122 toward u: i c-vity 124. The stationary member 112 extends into the pocket 124. Air is compressed which is pushed into the ca-c? ad 124 and around the fixed member 112. In the example FIG. 7, the sensor of
temperature 44 is mounted sb-e stationary member in cavity 124. For this reason, ur-drilling 126 can be provided through stationary torque and temperature sensor 44 is passed through bore 126 and placed at an end 12o of the stationary member. The positioning of the temperature sensor 44 in the discharger valve assembly places the temperature sensor in close proximity to the n. a ~ < and compression 17 and substantially isolates the sensor sensor from large temperature-reducing components, such as the frame and the head. This close zero with the compression chamber and this initial isolation of the head and the frame offer a measurement of the air temperature in the comp chamber ": ^ n. In addition, changes in temperature in the camera. The pressure is quickly detected by the sensor 44, due to the close proximity to the compression chamber and insulation of the frame 11 and of the head 1. The temperature sensor 44 may be placed in several other positions to detect the compressed air ten- ture provided by the compress. The temperature sensor 44 can be placed in the port of abi to 46, in the exhaust port, in the chamber ele.-17, or in lines 37 that connect the compressor 10 to the aepi. t 16, or in a discharger valve 54. In the modaiuir. - example, the sensor
The temperature is substantially isolated from large tep'i erruration reduction components such as the head and the frame. The temperature of the temperature sensor 44 in relation. to bulk components of temperature reduction to short if ruficativamente the time required to be able to detect c .mb_: > s in the temperature of the air compressed through the temperature sensor. While the invention is referred to with reference to specific modalities, it will be by means of a person with knowledge in the art that alternatives, modifications and modifications can be made.
Accordingly, the present invention encompasses alternatives, modifications and variations which may fall within the spirit and scope of the appended claims.