Control device for a compressor, compressor having the control device, and air conditioning system including the control device and the compressor

Abstract

To provide a compressor control module CCM which is adapted to control the output of a variable displacement swash plate compressor and improves the efficiency of the compressor.SOLUTION: The compressor control module CCM is adapted to: either directly calculate, or receive from an external source, for example an HVAC control unit, a signal indicating a desired or required output from a variable displacement swash plate compressor (30), also referred to as a control target or set value, for example, but not limited to, a suction pressure, a piston stroke length, an evaporator outlet air temperature, a refrigerant mass flow and / or a work done on fluid; receive the current / actual value; and receive or calculate the current rotation speed and angle of a swash plate (48), or the current piston stroke length and its reciprocating frequency, respectively, with respect to the rotation axis of the variable displacement swash plate compressor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present application relates to a compressor control module for controlling the operation of a variable displacement swash plate compressor, a variable displacement swash plate compressor including the compressor control module, and an air conditioning system.

Background Art

[0002] Generally, a vehicle air conditioning system includes a refrigerant compression cycle system for cooling and / or heating. The center of the refrigerant compression cycle is a compressor that compresses and circulates the refrigerant within the refrigerant cycle. The compressor is typically configured to maintain the pressure in the evaporator at a low level. The pressure in the evaporator is directly related to the temperature of the saturated refrigerant held in the evaporator, and thus by maintaining the pressure low, the compressor maintains the temperature in the evaporator low.

[0003] Variable displacement swash plate compressors are common for vehicle air conditioning systems. Variable displacement swash plate compressors are typically driven by a belt driven by a vehicle engine. The output of the compressor (such as the load on the compressor applied to the fluid or the work of the compressor) can be adjusted by changing the angle of the swash plate.

[0004] A variable displacement swash plate compressor is configured such that the inclination angle of the rotating swash plate affects the reciprocating length of the compression piston. The inclination angle of the swash plate is typically adjusted by varying the pressure difference between the crank chamber and the suction chamber of the variable displacement swash plate compressor. That is, when the pressure in the crank chamber increases by inducing high-pressure working fluid from the discharge chamber to the crank chamber, the pressure difference (Pc - Ps) between the crank chamber and the suction chamber increases, the swash plate angle decreases (i.e., it is moved orthogonally to the main shaft), and thus the piston stroke is reduced. Correspondingly, when the pressure in the crank chamber decreases, the swash plate angle increases, the piston stroke increases, and the compressor mass flow rate increases.

[0005] In the prior art, the crank chamber of a variable displacement swash plate compressor is always in communication with the suction chamber through a fixed orifice, often referred to as a "bleed port". When the control valve closes the passage between the crank chamber and the discharge chamber, the pressure in the crank chamber decreases through the bleed port until it reaches the pressure in the suction chamber. As a result, the tilt angle of the swash plate increases to the maximum, thus increasing the piston stroke and the compressor mass flow rate.

[0006] The control of the swash plate angle in the prior art is achieved by regulating the flow of high-pressure working fluid from the discharge chamber to the crank chamber.

[0007] Primarily, the resulting pressure difference (Pc - Ps) between the crankcase pressure and the suction pressure defines the swash plate angle.

[0008] This configuration of the prior art is well-known, simple but has drawbacks. The bleed port between the suction chamber and the crank chamber causes a pressure loss that would normally be used for cooling.

[0009] Another drawback is that the prior art control tends to become unstable under certain conditions.

[0010] The electronic control valve used in a so-called "externally controlled variable compressor" typically includes an operating rod driven by an electronic actuator such as a solenoid. The operating rod moves the valve body in response to the on / off state of the solenoid. The externally controlled variable compressor can adjust the temperature at the outlet of the evaporator, preferably within a range of up to 12°C. By adjusting the temperature in the evaporator, the AC system can be optimized for the cooling load, providing more efficient cooling and reducing power consumption.

[0011] Furthermore, the electric control valve in some embodiments can control the swash plate to be orthogonal to the main shaft by setting the output / load of the compressor to the minimum, so that a mechanism (usually a clutch) for turning the compressor on / off can be omitted, simplifying the structure and reducing the manufacturing cost.

[0012] Conventional technologies typically involve open-loop regulation of the suction pressure. A heating, ventilation, and air conditioning (HVAC) system sets the desired suction pressure for the compressor. The desired suction pressure is converted into a specific drive signal for the electronic control valve of the compressor, and the drive signal sets the swash plate position and thus the output / load of the compressor. The suction pressure is typically not measured. HVAC control uses only the vehicle cabin temperature and the evaporator air outlet temperature as control values. This structure is mostly stable, but since the suction pressure is not measured, there is no feedback that the actual suction pressure has been achieved. Therefore, the system is prone to static errors and hysteresis effects due to friction.

[0013] This application is a continuation application of the invention disclosed in Korean Patent Application KR10-2018-0010891, and discloses a compressor control module (CCM) for further improving the regulation of a compressor that can adjust the suction pressure according to the required cooling effect.

[0014] This disclosure includes a first communication passage (referred to as "P1" in KR10-2018-0010891) connecting the suction chamber and the crank chamber of a variable displacement swash plate compressor, and a second communication passage (referred to as "P2" in KR10-2018-0010891) connecting the discharge chamber and the crank chamber of the variable displacement swash plate compressor. This disclosure further discloses a four-way control valve that selectively opens and closes the first communication passage and the second communication passage, and thus can close or substantially close the bleed port.

Prior Art Documents

Patent Documents

[0015]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0016] By enabling pressure adjustment in both directions, the bleed port can be reduced or closed, substantially improving efficiency. However, closing the bleed port can make the system unstable, and a slight variation in the opening of the control valve can result in a large change in the swash plate angle. Closing or substantially closing the bleed port improves efficiency but complicates system control. The present invention describes a solution for precisely controlling a compressor with a closed or substantially reduced bleed port.

Means for Solving the Problems

[0017] This object is solved by the compressor control module (CCM) of claim 1, the variable displacement swash plate compressor of claim 10, and the air conditioning system of claim 14.

[0018] In particular, this object is solved by a compressor control module CCM adapted to control the output of a variable displacement swash plate compressor, the CCM comprising a) directly calculating, or receiving from an external source, e.g., an HVAC control unit, a desired or required output from the variable displacement swash plate compressor, also referred to as a control target or setpoint, such as, but not limited to, suction pressure, piston stroke length, evaporator outlet air temperature, refrigerant mass flow rate, and / or a signal indicating the work done on the fluid, b) receiving the current / actual value of the value described in a), c) receiving or calculating, respectively, the current rotational speed and angle of the swash plate with respect to the rotational axis of the variable displacement swash plate compressor, or the current piston stroke length and its reciprocation frequency, d) Optionally, receive or calculate additional current values from the compressor, air conditioning system, or vehicle, such as discharge pressure, crankcase pressure, delta pressure between suction pressure and crankcase pressure, evaporator outlet air temperature, and engine speed, e) Determine the difference between the desired or required output from the variable displacement swash plate compressor and the current output of the variable displacement swash plate compressor, f) Adapted to output a signal to the valve drive unit to adjust the angle of the swash plate so that the actual output of the variable displacement swash plate compressor approaches or becomes the same as the desired or required output obtained in step a), also taking into account the additional values received or calculated in c) and d).

[0019] These advantages include precise control of the compressor with the bleed port closed or substantially reduced.

[0020] One or more of the controller parameters of the controller can advantageously be adjusted during operation. This can be done in response to specific system variables (Ps, piston stroke length, RPM, Pd, evaporator air outlet temperature, humidity, etc.).

[0021] In one embodiment, the compressor control module CCM is adapted to repeat steps a) - f) until the current output of the variable displacement swash plate compressor approaches or becomes the same as the desired or required output from a), The CCM is preferably adapted to execute steps a) - f) in a given order.

[0022] In one embodiment, the CCM is further adapted to operate the desired or required output of the variable displacement swash plate compressor received in step a) based on one or more of the values received in c) and / or d).

[0023] For step a), the CCM can receive the desired or required output (control target value) of the variable displacement swash plate compressor and be adapted to manipulate this value based on one or more of the values received in c) and / or d).

[0024] In one embodiment, when the derivative of the piston stroke length is different from 0 or different from a specific tolerance band around 0, the upper and / or lower threshold differences between the crank chamber pressure and the suction pressure (Pc - Ps) are stored, the swash plate (SWP) angle increases when exceeding the upper threshold, and the SWP angle decreases when not reaching the lower threshold. The upper and / or lower threshold differences, or functions of the upper and / or lower threshold differences, are used for precise SWP angle control.

[0025] In one embodiment, the compressor rotational speed and / or its derivative are feedforwarded to the CCM to adjust the input and / or output of one and / or two or more control loops and improve the dynamic behavior when the compressor RPM changes.

[0026] In one embodiment, the signal to the valve drive unit is at least partially generated from the output of an online prediction controller such as model predictive control (MPC), IMC, neural network, and / or a multi-input single-output (MISO) controller.

[0027] In one embodiment, the signal to the valve drive unit is at least partially generated from the output of a PID controller, and the difference determined in step e) preferably becomes the input signal to the PID controller.

[0028] In one embodiment, at least one gain parameter of the PID controller is at least partially adjusted based on one or more measured or calculated values of the compressor, such as the suction chamber pressure and / or discharge chamber pressure and / or the piston stroke length and / or piston reciprocation frequency and / or opening level of the control valve.

[0029] In one embodiment, when the suction chamber pressure is low, the P parameter and / or the I parameter and / or the D parameter are smaller compared to when the suction chamber pressure is higher, and / or when the discharge chamber pressure is high, the P parameter and / or the I parameter and / or the D parameter are smaller compared to when the discharge chamber pressure is lower, and / or when the piston stroke length is small, the P parameter and / or the I parameter and / or the D parameter are larger compared to when the piston stroke length is larger.

[0030] In one embodiment, the CCM is an integral part of a variable displacement swash plate compressor.

[0031] In one embodiment, the variable displacement swash plate compressor does not include a bleed port or a bleed valve between any of the suction chambers and the crank chamber, or includes a bleed port with a reduced diameter.

[0032] In one embodiment, the variable displacement swash plate compressor includes at least one speed stroke sensor, and the speed stroke sensor can be adapted to monitor the amount of one or more piston stroke lengths and reciprocating speeds of the pistons of the variable displacement swash plate compressor and send this measurement to the CCM. The CCM can calculate the current angle of the swash plate and / or the piston stroke length of the variable displacement swash plate compressor based on the movement amount of one or more pistons, and is adapted to calculate the rotation speed (RPM) of the swash plate and the compressor based on the reciprocating speed of the pistons.

[0033] In one embodiment, the variable displacement swash plate compressor includes an electronically controlled valve connected to the CCM. The electronically controlled valve is adapted to direct pressure from the crank chamber of the variable displacement swash plate compressor to one or more of the suction chambers or from the discharge chamber to the crank chamber in response to receiving an output signal from the CCM in step f), thereby changing the angle of the swash plate.

[0034] In one embodiment, the variable displacement swash plate compressor is part of an air conditioning system.

[0035] In one embodiment, the air conditioning system is used in an automobile, and further, the CCM or the air conditioning system is adapted to operate so as to ensure that the temperature in the passenger compartment of the automobile is maintained at a temperature desired or set by the user of the automobile by controlling the suction pressure of the variable displacement swash plate compressor or the output of the coolant.

[0036] In one embodiment, the desired output of the variable displacement swash plate compressor is the amount of work done on the coolant and remains constant regardless of the driving force and rotational speed of the variable displacement swash plate compressor.

[0037] For the calculation of the target value, external conditions (such as temperature and humidity), solar radiation load on the vehicle, and other external signals such as the target and actual values of the evaporator air outlet temperature can be taken into consideration.

[0038] The variable displacement swash plate compressor may not be provided with a bleed port or a bleed valve between any of the suction chambers and the crank chamber, or may be provided with at least a bleed port or a bleed valve with a reduced diameter.

[0039] By removing the bleed port or the bleed valve or reducing its diameter, the internal pressure loss is reduced, thereby increasing the efficiency of the compressor and thus saving fuel.

[0040] By the signal output from the CCM in step f), the variable displacement swash plate compressor can change the pressure in the crank chamber, change the angle of the swash plate, and thereby increase or decrease the fluid output (such as the compressor mass flow rate output) from the variable displacement swash plate compressor.

[0041] The signal output from the CCM in step f) can affect the valve drive unit that drives the actuator to drive the valve body to open one of the communication passages. The first passage opens PcPs and increases the angle. The second passage opens PdPc and decreases the swash plate angle.

[0042] The variable displacement swash plate compressor can be provided with at least one speed stroke sensor, and the speed stroke sensor can monitor the amount of one or more piston stroke lengths and reciprocating speeds of the pistons of the variable displacement swash plate compressor and be adapted to send this measured value to the CCM. The CCM is adapted to calculate the current angle of the swash plate and / or the piston stroke length of the variable displacement swash plate compressor based on the movement amount of one or more pistons, and to calculate the swash plate and the rotational speed (RPM) of the compressor based on the reciprocating speed of the pistons.

[0043] The variable displacement swash plate compressor can be provided with at least one crankcase pressure sensor, and the CCM is adapted to use this information for step d) (optional).

[0044] The variable displacement swash plate compressor can be provided with at least one suction pressure sensor for measuring the suction pressure, and the CCM can be adapted to use this information for step b).

[0045] The variable displacement swash plate compressor can be provided with at least one delta pressure sensor for measuring the pressure difference between the crankcase pressure and the suction pressure, and the CCM is adapted to use this information for step d) (optional).

[0046] The CCM (or some parts of the CCM control algorithm) can be incorporated into the AC system controller (AC ECU). This can reduce costs.

[0047] The TXV can control the evaporator superheat temperature by adjusting the mass flow rate. The compressor controls the suction pressure, which may be highly related to the evaporator temperature.

[0048] The control algorithm of the CCM can be located on a PCBA including a microcontroller, a valve drive unit, a power supply, an input unit for reading sensors, and a communication unit for transmitting and / or receiving information between the AC ECU and / or the engine ECU.

[0049] The above other aspects, features, and advantages of the present disclosure will become more apparent from the following detailed description together with the accompanying drawings.

Brief Description of the Drawings

[0050]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0051] In order to improve controllability, a feedforward function may be required, which means that the compressor RPM value is used as an input to the controller to improve the dynamic behavior when the compressor RPM changes.

[0052] In one embodiment, the compressor RPM and / or its derivative is used as an input to the feedforward function to adjust the target piston stroke length value, for example, by adding or subtracting a specific value.

[0053] In one embodiment, this adjustment can also be done at different locations in the control circuit, for example, with the controller output value.

[0054] The feedforward function can also be used to further improve the dynamic behavior in relation to FIGS. 7, 8, and 9. Additional Ps information can be used to prevent icing of the evaporator.

[0055] In certain embodiments, it may be advantageous to adjust one or more controller parameters during operation depending on certain system variables (Ps, piston stroke length, RPM, Pd, evaporator air outlet temperature, humidity, etc.).

[0056] For example, the PID parameters (proportional, integral, and derivative parameters) can be adjusted according to the current Ps and / or Pd and / or the piston stroke length and / or the opening level of the control valve. When Ps is smaller, the P parameter and / or the I parameter and / or the D parameter can be different compared to the situation where the Ps pressure is large. This is because when Ps is larger, less control gas is sucked out from the crankcase. When Pd is larger, the P parameter and / or the I parameter and / or the D parameter can be made smaller compared to the situation where the Pd pressure is smaller. This is because when Pd is larger, more control gas is sent to the crankcase.

[0057] When the piston stroke length is small, the P parameter and / or the I parameter and / or the D parameter can be made larger compared to the situation where the stroke is larger.

[0058] It is advantageous to adjust the I parameter to increase the response of the controller according to the control deviation of the outer control loop. For example, when the control deviation is larger than a predetermined limit, the I parameter can set a larger value than when the control deviation is smaller.

[0059] Furthermore, in order to improve controllability, a feedforward function is advantageous for any of the embodiments described herein.

[0060] This is because due to the high-speed RPM change, Ps increases or decreases. If these RPM changes are not used as input values to the controller, the suction pressure response (system-related) is very slow, so the controller response to such RPM changes becomes very slow. In this case, the Ps pressure logically fluctuates, and the unintended increase or decrease in the Ps level / mass flow rate increases the energy consumption.

[0061] The compressor RPM value is used as an input to the controller to improve the dynamic behavior when the compressor RPM changes.

[0062] For example, the compressor RPM and / or its derivative can be used as an input to a feedforward function to adjust the input and / or output of one and / or two or more controller loops.

[0063] Although the exemplary embodiments have been described above, the scope of the present disclosure is not limited to the specific embodiments, and the present disclosure can be appropriately modified within the scope described in the claims. For example, the suction pressure sensor 401 can be disposed in one of the suction chamber of the compressor, the outlet end of the evaporator, and the working fluid pipe between the evaporator and the compressor.

[0064] Although cascade control, PI, and PID are mentioned as examples, any other type or structure of control mechanism, such as model predictive control (MPC), internal model control (IMC), an online predictive controller such as a neural network, and a multi-input single-output (MISO) controller, can be used by those skilled in the art if applicable.

[0065] Hereinafter, an embodiment of a compressor control module (CCM) according to the present disclosure, a variable displacement swash plate compressor having the CCM, and an air conditioning system including the CCM and the variable displacement swash plate compressor will be described in detail with reference to the accompanying drawings.

[0066] An example of a variable displacement swash plate compressor is shown in FIG. 1. The exemplary variable displacement swash plate compressor can include a central hole 11 formed through the center of a cylinder housing 10 and a plurality of cylinder holes 13 formed through the cylinder around the central hole 11. A piston 15 can be movably disposed within the cylinder hole 13, and the piston 15 can compress the working fluid within the cylinder hole 13.

[0067] The front housing 20 can be coupled to the end of the cylinder housing 10. The front housing 20 and the cylinder housing 10 can together form a crank chamber 21 inside. A suction chamber 31 that selectively communicates with the cylinder bore 13 can be formed in the rear housing 30. The suction chamber 31 can send the working fluid to be compressed into the cylinder bore 13.

[0068] A discharge chamber 33 can be formed in the rear housing 30. A four-way control valve 100 can be arranged on the side surface of the rear housing 30. The control valve 100 adjusts the angle of the swash plate 48 by alternatively adjusting the opening levels of the flow path (P1) between the crank chamber 21 and the suction chamber 31 and the flow path (P2) between the discharge chamber 33 and the crank chamber 21.

[0069] The rotating shaft 40 can be rotatably arranged through the central hole 11 of the cylinder housing 10 and the shaft hole 23 of the front housing 20. The rotating shaft 40 can be rotated by the power from an engine (not shown). The rotating shaft 40 can be rotatably arranged in the cylinder housing 10 and the front housing 20 by bearings 42.

[0070] A rotating body 44 is arranged in the crank chamber 21, and the rotating shaft 40 passes through the center of the rotating body 44 so that the rotating body 44 rotates integrally with the rotating shaft 40. The rotating body 44 is substantially formed in a disc shape and is fixed to the rotating shaft 40, and a hinge arm (not shown) protruding to the side of the rotating body 44 can be formed.

[0071] The swash plate 48 can be hingedly attached to the rotating body 44 on the rotating shaft 40 so as to rotate together. The swash plate 48 can be arranged such that the angle with respect to the rotating shaft 40 is variable according to the discharge capacity of the compressor. That is, the swash plate 48 can be moved between a position orthogonal to the axis of the rotating shaft 40 and a position inclined at a predetermined angle from the rotating shaft 40. The swash plate 48 can be connected to the piston 15 through a shoe (not shown) at the edge. That is, the edge of the swash plate 48 is connected to the connecting portion 17 of the piston 15 through the shoe, and thus the piston 15 reciprocates in the cylinder bore 13 by the rotation of the swash plate 48.

[0072] A semi-inclined spring (not shown) that provides elasticity can be arranged between the rotating body 44 and the swash plate 48. The semi-inclined spring can be arranged around the outside of the rotating shaft 40 and provides elasticity such that the inclination angle of the swash plate 48 decreases.

[0073] In FIG. 1, the path connecting the crank chamber 21 and the suction chamber 31 is defined as the first communication passage P1, and the path connecting the discharge chamber 33 and the crank chamber 21 is defined as the second communication passage P2. These passages are indicated by arrows in FIG. 1, and due to the pressure differences among the suction chamber, the crank chamber, and the discharge chamber, the working fluid flows in the directions indicated by the arrows.

[0074] When the first communication passage P1 is opened, the crank chamber and the suction chamber communicate with each other, and thus the pressure in the crank chamber decreases. Accordingly, the inclination angle of the swash plate increases, and as a result, the piston stroke increases. Further, when the second communication passage P2 is opened, the crank chamber and the discharge chamber communicate with each other, and thus the pressure in the crank chamber increases. Accordingly, the inclination angle of the swash plate decreases, and the piston stroke decreases.

[0075] Referring to FIG. 2, the horizontal axis indicates the movement distance of the valve body of the four-way control valve, and the vertical axis indicates the opening levels of the first communication passage (P1) and the second communication passage (P2).

[0076] In the left region, it is shown that as the valve body moves downward, the second communication passage P2 gradually closes and later closes completely. In the right region, it is shown that as the valve body moves downward, the first communication passage P1 gradually opens. It should be noted that the part where the opening and closing of the first and second communication passages are reversed is seen in the region near the origin, and preferably there is no part where both communication passages are open. This is because if both communication passages are open, it should lead to substantial leakage of the cooling fluid through the crank chamber. For ease of control, it is also possible not to completely close the bleed port. As a result, both passages will open slightly simultaneously. This increases the controllability.

[0077] In this embodiment, the control valve does not use the entire part shown in FIG. 2, but operates within the region shown as the "control region". Depending on the leakage from the discharge chamber to the crank chamber via the piston, most of the control region is positioned at the part where the opening and closing of the first communication passage P1 are adjusted. This is in contrast to the prior art where control is performed by opening a channel between the discharge chamber and the crank chamber.

[0078] The control of the control valve can aim to achieve a specific suction chamber pressure required by the HVAC system. To improve the accuracy of the suction pressure achieved with the bleed port closed, a pressure sensor can be included on the evaporator side of the refrigeration cycle, preferably within the suction chamber of the compressor. The sensor measures the suction pressure. It can further include a control unit including a controller (such as a PI / PID controller), and can be configured to adjust the control valve to bridge the gap between the target suction pressure and the actual suction pressure. Feedback from the suction pressure within the closed loop increases the stability and accuracy of the suction pressure control. However, the delay within the refrigeration cycle rather becomes longer, causing controllability problems and potentially complicating the control.

[0079] As shown in FIG. 3, the compressor control module (CCM) can be part of the vehicle's heating, ventilation, and air conditioning (HVAC) system.

[0080] The HVAC control module can receive a cooling request from a passenger. The HVAC control module provides a target value to the CCM that controls the control valve of the compressor. To improve the control of the compressor, sensor values are fed back to the CCM.

[0081] The compressor can affect the pressure in the evaporator and the evaporator air outlet temperature, measure these, and provide them to the HVAC control module.

[0082] Feedback from the measured value of the swash plate angle can be performed faster than feedback from the suction pressure sensor. Typically, feedback from the swash plate angle can be significantly faster than feedback from the suction pressure sensor in response to changes in compressor load.

[0083] By using sensors to provide information used to calculate the current swash plate position and / or compressor mass flow rate, problems related to delays in the refrigeration cycle are addressed. In addition, by measuring the swash plate angle, problems caused by hysteresis due to friction of the swash plate, etc. are significantly reduced. As a result, the control of the compressor becomes faster and more accurate.

[0084] FIG. 4 is a graph showing the adjustment of the suction pressure and the change in the valve opening level in response to an increase in the cooling request according to an embodiment of the present invention. An increase in the cooling effect is required by a user's selection or other reasons. The CCM (and / or HVAC system) determines the suction pressure at which the corresponding cooling effect is achieved and sets the target suction pressure accordingly. The target suction pressure is input to the control unit. The suction pressure set value is indicated by a dotted line in FIG. 4.

[0085] Next, the control unit applies a control input to the electric control valve by applying a current to the electromagnetic actuator, and thus the opening level of the first communication passage P1 increases. When the first communication passage P1 increases, the crank chamber and the suction chamber communicate with each other, and thus the pressure in the crank chamber decreases. The inclination angle of the swash plate increases, and thus the stroke of the piston increases. As a result, the load on the compressor increases (assuming that the rotational speed of the swash plate is constant), and the pressure on the evaporation side of the refrigeration cycle decreases. The measured suction pressure decreases, and using the control algorithm of the controller, the control unit is configured to adjust the input to the control valve so that the target suction pressure is maintained.

[0086] Figure 5 is a graph showing the change in suction pressure and the change in valve opening level in the process of reducing the stroke of the piston according to an embodiment of the present invention. Due to user selection or other reasons, the required cooling decreases. To reduce the cooling, as described above, the stroke length of the piston can be reduced. For this purpose, the control unit (such as an AC ECU) determines the suction pressure at which the corresponding stroke can be obtained and sets that suction pressure as the target suction pressure. The suction pressure set value is indicated by a dotted line in Figure 5. When the target suction pressure value changes to a larger value (i.e., less cooling), in accordance with an instruction from the control unit, the current applied to the electromagnetic actuator is decreased or blocked, and accordingly the first communication passage is closed and the second communication passage is opened. When the second communication passage P2 opens, the crank chamber and the discharge chamber communicate with each other, and thus the pressure in the crank chamber increases. Accordingly, the inclination angle of the swash plate decreases, and the stroke of the piston decreases. The output of the compressor decreases, and the evaporator temperature decreases.

[0087] The above relates to a solenoid actuator. A person skilled in the art should be able to easily adapt the present invention for use with a step actuator or any other suitable actuator.

[0088] When the P2 channel is open for a sufficiently long time, the pressure in the crank chamber becomes the same as the discharge pressure, and thus the inclination angle of the swash plate decreases to its minimum value. If the compressor does not maintain a low suction pressure, the pressure in the evaporator increases due to the intrusion of additional refrigerant through the heating and thermal expansion valve. When the suction pressure reaches the target value, current is applied to the actuator again to increase the stroke length and maintain an appropriate suction pressure.

[0089] As can be seen in FIGS. 4 and 5, in order to compensate for the leakage in the cylinder into the crankroom, the static suction pressure may require that the P1 opening level be at a constant level.

[0090] Exemplary sensors that can provide information used to calculate the current compressor mass flow rate include sensors that provide information regarding the rotational speed and angle of the swash plate.

[0091] Another example of a sensor that can provide information used to calculate the current swash plate angle and / or compressor mass flow rate includes a sensor that provides information regarding the number of reciprocations of the piston and the stroke length. The current swash plate angle and / or compressor mass flow rate can also be measured and / or calculated by other methods.

[0092] The swash plate rotational speed can be made the same as the number of piston reciprocations. The swash plate angle can be derived from the piston stroke length from pre-set data regarding the structure of the compressor including the structure of the swash plate and the piston.

[0093] FIG. 6 shows a flow diagram of a method that can be used by the CCM to control the output (such as the current operation of the compressor) of a variable displacement swash plate compressor. This method a) directly calculates, or receives from an external source, such as an HVAC control unit, a signal indicating the desired or required output from the variable displacement swash plate compressor, such as, but not limited to, suction pressure, piston stroke length, evaporator outlet air temperature, refrigerant mass flow rate, and / or work performed on the fluid 610, b) Receive the current / actual value of the value described in a) 620, and c) Receive or calculate the current rotational speed and angle of the swash plate with respect to the rotating shaft of the variable displacement swash plate compressor, or the current piston stroke length and its reciprocation frequency, respectively 630, and d) Optionally, but not limited to, receive or calculate additional current values from the compressor, air conditioning system, or vehicle, such as discharge pressure, crankcase pressure, suction pressure, delta pressure between the suction pressure and the crankcase pressure, evaporator outlet air temperature, engine speed 640, and e) Determine the difference between the desired or required output from the variable displacement swash plate compressor and the current output of the variable displacement swash plate compressor 650, and f) Output a signal to adjust the angle of the swash plate to the valve drive unit so that the actual output of the variable displacement swash plate compressor approaches or becomes the same as the desired or required output obtained in step a), taking into account the additional values received or calculated in c) and d) 660.

[0094] This CCM can drive a control valve within a closed-loop control that can include the use of input signals from additional sensors to adjust the pressure ratio between Pc and Ps and regulate the swash plate angle and output of the compressor.

[0095] In one example, the CCM includes an automated control algorithm that includes an inner loop that adjusts a control valve actuator to achieve a specific swash plate angle and / or compressor discharge rate that is cascaded by an outer control loop. The inner loop can be closed by an input from a sensor that provides a measured value that can be used to determine the swash plate angle or the current compressor discharge rate. The delay can be made relatively small compared to the delay from a suction pressure sensor, such as a delay well below 1 second.

[0096] One embodiment of the regulation of the suction pressure in which the inner loop adjusts the swash plate angle is shown in FIG. 7. The inner loop can include a PID controller that adjusts the piston stroke length. The feedback delay time of the inner control loop is typically much less than 1 second.

[0097] The outer loop can include a PID controller that regulates Ps from the refrigeration cycle and the target Ps set point from the HVAC control system. The inner loop can include piston stroke length feedback. The outer loop can include Ps sensor feedback from a pressure sensor on the suction side of the refrigeration cycle, preferably in the suction chamber of the compressor.

[0098] Depending on the A / C system, the delay of the outer loop is longer than that of the inner loop. The piston stroke length feedback is significantly faster than when only suction pressure measurement feedback is used. By measuring the piston stroke length, the stability and response time of the control system can be substantially improved. The direct piston stroke length feedback also overcomes the controllability problems caused by the friction against the movement of the swash plate. There is a possibility of measuring the wrong position of the swash plate, and the control valve level can be adjusted accordingly until the correct swash plate angle is achieved.

[0099] In addition, the position of the swash plate can be monitored before and / or during operation, and specific faults can be detected if the swash plate does not respond as expected to changes in the control valve.

[0100] An exemplary CCM can also include a piston reciprocation speed sensor. Measurements from the piston reciprocation speed sensor can be provided in a feed-forward manner to an inner and / or outer controller with information regarding the number of piston reciprocations, enabling anticipation of changes in engine rpm and adjustment of a control valve such that the stroke length compensates for an increase in the number of piston reciprocations and maintains a constant work load on the fluid. If the engine speed suddenly increases, an increase in compressor speed can be, for example, fed forward to an inner loop, reducing the stroke length and thus preventing a sudden surge in compressor output. Such a surge would typically result in torque peaks, unnecessary cooling, and wasted energy.

[0101] As an example, the number of piston reciprocation cycles and the piston stroke length of a piston can be calculated by signals received from at least one speed stroke sensor, such as the speed stroke sensor described in European Patent Application 19159899.4.

[0102] When information regarding the rotational speed of a swash plate, such as a feed-forward swash plate rotational speed, is not used, changes in compressor speed are only recognized by the controller once the suction pressure changes. In such a case, when the compressor speed increases due to a change in engine rpm, the cooling effect of the air conditioning system becomes too large until the suction pressure stabilizes around a higher desired level / value, causing discomfort to passengers and wasting energy. By sensing and responding to changes in compressor rotational speed (such as by feed-forward), the CCM can react to speed fluctuations at an earlier stage.

[0103] Examples of piston positioning sensors and piston speed sensors include eddy current sensors, cylinder pressure sensors, Hall sensors, magnetoresistive sensors, capacitive sensors, and inductive sensors.

[0104] By using the piston stroke length information corresponding to the swash plate angle, the piston stroke length can be directly controlled within the inner control circuit of the cascade controller. As a result, the quality of control is significantly improved.

[0105] For the second control loop, instead of the piston length information, it is also possible to use the value of the difference (Pc - Ps) between the crank chamber pressure and the suction chamber pressure.

[0106] Figure 8 shows the control according to an embodiment of the present invention. An additional sensor is included to measure the crank chamber pressure. The pressure difference (Pc - Ps) between the crankcase pressure and the suction pressure is calculated and used as the actual value for the third controller according to Figure 8.

[0107] To change the swash plate (SWP) angle, the pressure difference (Pc - Ps) between Pc and Ps needs to be below or above a specific threshold value. A smaller Pc - Ps pressure value increases the SWP angle, and a larger Pc - Ps pressure value decreases the SWP angle.

[0108] When Pc - Ps is between the upper threshold value and the lower threshold value, the SWP does not move at all due to static friction.

[0109] By using Pc - Ps, since Pc - Ps directly affects the movement of the swash plate, the control behavior regarding the response time and the quality of control is further improved.

[0110] The input to the first controller in Figure 8 is the difference between the suction chamber target pressure value and the measured suction chamber pressure value ("barA").

[0111] The output signal of the first controller indicates the target piston stroke length compared with the measured value. This difference is used as the input to the second controller ("mm"). This difference is used by the second controller to output the target pressure delta (Pc - Ps) between the crank chamber and the suction chamber.

[0112] This output signal of the second controller is compared with the measured Pc-Ps value, and the difference is used as an input to a third controller that adjusts the electric control valve to reach this value.

[0113] The output value of the second controller, i.e., the Pc-Ps value, has no upper or lower limit and depends on the control deviation (input) of the second controller and its control parameters.

[0114] Figure 9 shows the control according to an embodiment of the present invention. Since the Pc-Ps threshold values for increasing and decreasing the SWP angle depend on different parameters (RPM, stroke, friction, temperature, etc.), knowledge of the exact threshold values is an advantage.

[0115] For example, under certain conditions, the controller adjusts the compressor to decrease the SWP angle (by opening the PdPc passage while keeping the PsPc passage closed). When Pd is very large, or in this case, when the PID parameters have rather large gains, the amount of control gas passing through the PdPc passage may rather be very large, and as a result, the Pc pressure increases very much, and thus the Pc-Ps pressure also increases rapidly, and in this case, it should far exceed the current Pc-Ps threshold value that may not be suitable for the operating conditions. The SWP angle decreases too rapidly, and as a result, the controller needs to correct the SWP angle. In a specific situation, this behavior may cause vibration of the swashplate angle. This problem is overcome by accurately determining the Pc-Ps threshold value during operation (on-time / real-time).

[0116] By measuring the piston stroke length (related to the SWP angle) and the Pc and Ps pressures, it is possible to determine the actual Pc-Ps threshold value in the current operating state.

[0117] When the SWP angle changes, this means that its derivative is different from 0, or different from a specific tolerance band around 0, and the corresponding Pc - Ps value logically becomes the current lower Pc - Ps threshold or the current upper Pc - Ps threshold, and is stored in the "lower threshold variable" or "upper threshold variable".

[0118] This can be done permanently, which means that the Pc - Ps threshold is always updated. The "second controller" uses these thresholds to precisely control the movement of the SWP angle.

[0119] Figure 10 shows the control according to an embodiment of the present invention. The HVAC control unit provides the piston stroke length as a target value for the CCM. In this case, a single controller is sufficient to control the piston stroke length.

Claims

Claim 1 A variable displacement swash plate compressor, comprising a compressor control module CCM adapted to control the output of the variable displacement swash plate compressor as an integral part thereof, wherein the compressor control module CCM a) directly calculates, or receives from an external source, e.g., an HVAC control unit, a signal indicative of a desired or required output from the variable displacement swash plate compressor (30), such as, but not limited to, suction pressure, piston stroke length, evaporator outlet air temperature, refrigerant mass flow rate, and / or work done on the fluid, b) receives the current / actual value of the value described in a), c) receives or calculates, respectively, the current piston stroke length and the current rotational speed and angle of the swash plate (48) relative to the rotational axis of the variable displacement swash plate compressor, or the current piston stroke length and the number of reciprocations thereof, e) determines the difference between the desired or required output from the variable displacement swash plate compressor and the current output of the variable displacement swash plate compressor, f) is a compressor control module CCM adapted to output to a valve drive unit a signal for adjusting the angle of the swash plate (48) such that the actual output of the variable displacement swash plate compressor approaches or becomes the same as the desired or required output obtained in step a), taking into account additional values received or calculated in c), wherein upper and lower threshold values of a pressure difference (Pc - Ps) between a crankcase pressure and a suction pressure required to move the swash plate (48) are determined during operation from the current piston stroke length, wherein the swash plate angle increases when the pressure difference (Pc - Ps) exceeds the upper threshold value and the swash plate angle decreases when the pressure difference (Pc - Ps) is lower than the lower threshold value, wherein the upper and lower threshold values are used for swash plate angle control, wherein the variable displacement swash plate compressor comprises an electronically controlled valve (100) connected to the compressor control module CCM, and the electronically controlled valve (100) is adapted to change the angle of the swash plate (48) by inducing pressure from one or more of a crank chamber (21) of the variable displacement swash plate compressor to a suction chamber (31) or from a discharge chamber (33) to the crank chamber (21) in response to receiving the signal output from the compressor control module CCM in step f), A variable displacement swash plate type compressor that does not have a bleed port or a bleed valve between the suction chamber (31) and the crank chamber (21) of the variable displacement swash plate type compressor.

2. The variable displacement swash plate type compressor according to claim 1, further adapted to repeat steps a), b), c), e) and f) until the current output of the variable displacement swash plate type compressor approaches or becomes the desired or required output from a).

3. The variable displacement swash plate type compressor according to claim 1 or 2, further adapted to operate the desired or required output of the variable displacement swash plate type compressor received in step a) based on one or more of the values received in c).

4. d) Receive or calculate additional current values from the compressor, air conditioning system, or vehicle of discharge pressure, crankcase pressure, delta pressure between suction pressure and crankcase pressure, evaporator outlet air temperature, and / or engine speed, In the output of the signal in f), the additional current values received or calculated in d) are also taken into account, The variable displacement swash plate type compressor according to any one of claims 1 to 3.

5. Feed forward the compressor rotation speed and / or its derivative to the compressor control module CCM to adjust the input and / or output of one and / or two or more controller loops and improve the dynamic behavior when the compressor rotation speed RPM changes. The variable displacement swash plate type compressor according to any one of claims 1 to 4.

6. The signal to the valve drive unit is at least partially generated from the output of an online prediction controller such as model predictive control (MPC), IMC, neural network, and / or a multi-input single-output (MISO) controller. The variable displacement swash plate type compressor according to any one of claims 1 to 5.

7. The signal to the valve drive unit is at least partially generated from the output of a PID controller, and the difference determined in step e) preferably becomes an input signal to the PID controller. The variable displacement swash plate type compressor according to any one of claims 1 to 6.

8. At least one gain parameter of the PID controller is at least partially adjusted based on one or more measured or calculated values of the compressor of the suction chamber pressure and / or discharge chamber pressure and / or piston stroke length and / or number of piston reciprocations and / or opening level of the control valve. The variable displacement swash plate compressor according to claim 7.

9. When the suction chamber pressure is low, the P parameter and / or I parameter and / or D parameter are smaller compared to when the suction chamber pressure is higher, and / or When the discharge chamber pressure is high, the P parameter and / or I parameter and / or D parameter are smaller compared to when the discharge chamber pressure is lower, and / or When the piston stroke length is small, the P parameter and / or I parameter and / or D parameter are larger compared to when the piston stroke length is larger. The variable displacement swash plate compressor according to claim 8.

10. Comprising at least one speed stroke sensor, the speed stroke sensor being adapted to monitor the amount of piston stroke length and reciprocating speed of one or more pistons of the variable displacement swash plate compressor and send this measured value to the compressor control module CCM, the compressor control module CCM being adapted to calculate the current angle of the swash plate and / or the piston stroke length of the variable displacement swash plate compressor based on the amount of movement of the one or more pistons, and to calculate the swash plate and the compressor rotational speed (RPM) based on the reciprocating speed of the pistons. The variable displacement swash plate compressor according to any one of claims 1 to 9.

11. An air conditioning system comprising the variable displacement swash plate compressor according to any one of claims 1 to 10.

12. The air conditioning system is used in an automobile, and further, The air conditioning system according to claim 11, wherein the compressor control module CCM or the air conditioning system is adapted to operate so as to ensure that the temperature in the passenger compartment of the vehicle is maintained at a temperature desired or set by the user of the vehicle by controlling the suction pressure or the output of the coolant of the variable displacement swash plate compressor.

13. The desired output of the variable displacement swash plate compressor is the amount of work done on the coolant and remains constant regardless of the driving force and rotational speed of the variable displacement swash plate compressor. The air conditioning system according to claim 11 or 12.

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