DE9321378U1 - Universal retrofit system for climate control in a vehicle passenger compartment - Google Patents

Description

INTERDYNAMICS, INC., Brooklyn, New York, VStA 14887

UNIVERSAL RETROFIT SYSTEM FOR CLIMATE CONTROL OF A VEHICLE PASSENGER COMPARTMENT

Background of the invention

The invention relates to a universal retrofittable or subsequently installed climate control system for a motor vehicle, which is also referred to below as climate control system.

Climate control systems are becoming increasingly popular throughout the world. Many new motor vehicles are equipped with a climate control system as standard, but the cost of such a system can be relatively high. However, there are many automobiles and other motor vehicles throughout the world which have air conditioning and heating systems but do _not have a climate control system. A climate control system is generally understood to be a system which allows the driver to set the passenger compartment temperature to a desired value. A climate control system therefore operates in such a way that it maintains the set temperature regardless of the external ambient temperature.

Because of considerable differences between the heating and air conditioning systems of different manufacturers, it is extremely difficult to retrofit a universally usable climate control system. Attempts have been made to retrofit climate control systems, but these have generally been extremely expensive and have had to be adapted to the specific vehicle systems, and the retrofitting of such systems has also been extremely costly. Apart from the cost, the main disadvantage has been that the retrofit systems cannot be fitted to different automotive systems. This lack of universality has hindered the adoption and use of such systems.

One aim of the invention is therefore to create a climate control system that can be retrofitted as universally as possible, which is also referred to below as a built-in climate control system. This is also where the title of the invention comes from, which is intended to be used in particular in any motor vehicle that already has a heating and air conditioning system.

The built-in climate control system to be created according to the invention should be very easy to install even by skilled workers in a sufficiently efficient and economical manner,

The built-in climate control system to be created should also have a wide application and use, and it should be economical to manufacture, assemble and install.

Finally, the built-in climate control system to be created should advantageously be operated in such a way that it makes the comfort for the passengers as high as possible.

Further objects, advantages and features of the invention will become apparent from the following description.

Statement of the invention

The system is preferably a closed loop climate control system that can be retrofitted universally into virtually any water-cooled automobile, van, truck, etc.

The system according to the invention essentially contains the following four main components or main assemblies:

1) A control or monitoring module. This is preferably a compact unit which can advantageously be offered in four different configurations, namely for mounting or installation on a vertical or horizontal base such as a board, a panel, a cushion, etc., for mounting or installation in the DIN style and for mounting or installation in the amateur radio microphone style. These configurations should allow

the control module can be mounted in a highly flexible manner so that it can be easily seen or viewed by the driver of the vehicle and is located within the driver's reach. Typical mounting or mounting areas are the instrument panel, the center console or the door panel on the driver's side,

The control module preferably contains a liquid crystal display, which shows system and operating states, as well as system and operating parameters. Furthermore, buttons are provided, advantageously six buttons, which are used to enter data into the system. Both the liquid crystal display and the key caps or key covers are backlit. The lighting level is advantageously automatically reduced when the vehicle headlights are switched on.

The actual attachment or mounting of the control module to the vehicle can be done in different ways, (a) For example, the control module can be attached directly to the dashboard or any other flat surface with a double-sided adhesive tape, (b) The control module can also be attached to a mounting plate which is then attached to the mounting surface, for example by explosive rivets or self-tapping screws (the mounting plate can have a curved rear surface so that it can adapt to a curved mounting surface), (c) in the case of amateur radio microphone type attachment , a bracket or clamp holder can be provided on the cushion, instrument panel, dashboard, etc. in such a way that the control module, while remaining connected to its connection point, for example via a spiral cable, can be removed from the holder and held in the hand to facilitate the operation of the buttons and to better read the display, (d) In the DIN design, the control module can be installed directly in an extra radio slot according to DIN or can be installed in a corresponding panel which can then be can be cut to fit any opening.

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2) Main or power module. The power module is preferably housed in a heat sink housing, such as a molded or extruded aluminum housing. This assembly is designed to be mounted as unobtrusively as possible, for example under the dashboard, under a front seat, in the trunk, etc. The power module houses the bulk of the electronics including a microprocessor, a switching power supply for the blower or fan speed, an air conditioning relay, a manual shunt relay, a heater valve driver circuit, etc. A choke to reduce electromagnetic interference may be included as a peripheral assembly. Wiring to the vehicle and related components may be via a connector on a molded cable.

3) Intake assembly. This assembly contains a thermistor holder, a fan assembly and a cable and hoses connected to it. The purpose of the intake assembly is to determine the ambient temperature inside the passenger compartment of the vehicle. Only in this way is it possible for the microprocessor to be able to evaluate the prevailing temperature inside the vehicle and react accordingly. The actual temperature measurement is carried out by means of a thermistor which operates as linearly as possible in the desired temperature range. The thermistor is housed in a holder made of molded plastic. The holder can be mounted in a hole in the dashboard of the vehicle in such a location that the ambient temperature to which the vehicle passengers are exposed is approximated as closely as possible.

The fan unit contains a small, preferably flat fan housed in a molded housing. The housing is designed so that the fan draws air in through a hose connection nipple on the top and expels it through the open space formed by

stretched support feet on the floor. The purpose of the fan assembly is to draw air through the thermistor holder. This serves several purposes including: (a) drawing air from inside the passenger compartment into the thermistor holder to obtain an averaged rather than a highly localized temperature reading, (b) dramatically reducing the thermistor thermal time constant (adaptation time to a temperature change) since thermistors are slow to respond in still air, (c) minimizing any microclimate effects otherwise caused by self-heating of the thermistor due to the energy consumed by the thermistor or by the thermal inertia of the housing itself.

4) Heater valve. A solenoid operated, normally open heater valve is provided to control the flow of refrigerant or coolant into the vehicle's heat exchanger and thereby provide a means of controlling heat in the passenger compartment. The valve is located in the supply line to the heat exchanger in series with the original or originally installed valve, the so-called "OEM valve" if one exists. Instead of controlling or regulating the OEM valve, the invention provides the separate valve because there are many different systems of OEM valve control (mechanical, electrical, vacuum, multi-vacuum) and many vehicles are not equipped with heater valves at all, but use air-diverting flaps instead of heat control.

The use of this solenoid valve is an important contribution to the universal use of the climate control system according to the invention. A normally open valve, i.e. a valve that is open when not energized or de-energized, makes this part of the system fail-safe, in that the user can return to manual operation of the system without losing the heating function, especially in the event of a fault or

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Failure of the microprocessor, valve solenoid or related driver or control circuits. The valve can be supplied in a number of different connection sizes so that it can accommodate the inside diameter of all common heater hoses,

Although the valve can be either fully open or fully closed, proportional control is made possible by changing the duty cycle or percentage of opening time. Due to the relatively long thermal time constant of the heat exchanger, a sufficiently constant and predictably variable temperature can be achieved in the heat exchanger.

Integral with the valve assembly is a refrigerant threshold temperature thermostat which is an electrical device that holds a circuit open below a specified temperature and closes and holds the circuit closed when the specified threshold temperature is reached. The purpose of this thermostat is to monitor the coolant or refrigerant temperature and to notify the microprocessor when that temperature has reached a sufficiently high level to indicate that requested heat is available _o Until the thermostat closes, the fan is turned off (in automatic fan mode only) to prevent cold air from being blown onto the passengers.

An advantageous embodiment of the system preferably contains a further structural unit, namely:

5) Outside temperature sensor. This assembly is mounted under the front bumper of the vehicle and contains a temperature sensing integrated circuit that senses the outside air temperature. This sensor assembly is thermally bonded (using a special potting compound) to the molded plastic housing in which it is sealed.

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Operation

The user or operator selects the temperature he or she desires inside the vehicle using a warmer or up button and a colder or down button on the control module to change the set temperature, which is digitally displayed on the liquid crystal display. The microprocessor compares the desired or set temperature to the ambient temperature inside the vehicle, as sensed by the intake assembly. The comparison of these two temperatures indicates that the vehicle interior is either colder or warmer than the preset set temperature, or equal to the desired temperature. The control algorithm stored in the microprocessor initiates appropriate actions to bring the interior temperature into equilibrium with the preset temperature. This is accomplished by turning on either the heater or the air conditioning (cooling) and changing the fan speed.

There are five basic modes of fully automatic operation, each defined by the direction and magnitude of the difference between the temperature inside the vehicle and the preset set point temperature (Delta T). ₀ In Full Heat mode, the fan is at full speed and the heater valve is fully open. This mode provides the maximum amount of heat to warm the interior of the vehicle as quickly as possible. In Delta Heat mode, which occurs when Delta T is 5 ⁰ C (9 ⁰ F) or less, as the passenger compartment temperature approaches the desired set point temperature, the fan speed and heater valve duty cycle are gradually reduced. The closed loop control algorithm continually monitors and modifies parameters to accommodate the many possible environmental variables (including, but not limited to, outside temperature, solar radiation, etc.).

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ventilation, number of passengers, heat loss or heat gain through the windows and other surfaces, etc.) _&bgr;

In the steady state or balanced mode, where the measured passenger compartment temperature matches the desired set point temperature, the heater valve is closed and cooling or air conditioning is turned off. The blower or fan speed is gradually reduced to a minimum speed, unless temperature changes are again detected inside the passenger compartment.

In full cooling mode, cooling or air conditioning is on and the fan runs at full speed. In delta cooling mode, cooling or air conditioning is on and the fan speed is varied to meet the conditions according to a fixed baseline control formula. To minimize passenger discomfort, a delay of two measurement periods (10 s) is built into the control algorithm, which prevents heat from being supplied to the passenger compartment if the ambient temperature inside the vehicle exceeds the setpoint temperature (from the delta cooling zone) and the delta heating zone is entered.

The control loop algorithm and the universally applicable heating valve make the climate control system according to the invention a truly universal system that not only adapts to the different requirements of the weather and the environment, but also adapts in a unique way to the different requirements and conditions of completely different vehicles.

In addition to the self-correcting capability of the algorithm, various short-circuit pins are provided within the force module, allowing the installer to further tailor the system to the specific application. The variable or adjustable parameters include minimum fan speed in heating and air conditioning mode, temperature update rates, temperature selection in degrees Celsius

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or degrees Fahrenheit, symbols in English or in a generally understandable manner, etc.

A preferred embodiment of the invention will be explained below with reference to drawings.

Short description: of the drawings Showing:

Fig. 1 is a block diagram of a built-in climate control system according to the invention,

Fig. 2 is a block diagram of the force module/control module interface in the system according to the invention,

Fig. 3 and 4 are block diagrams of the force module and control module or control head and associated elements according to the invention.

-10- Detailed description of the invention

The installation kit is a retrofit kit that can be universally installed in most cars or vehicles manufactured worldwide.

FIG. 1 is a block diagram of the system. It contains a main or power module 10 which is essentially the brain or control center of the entire system. Everything is fed into or controlled by the power module. The power module contains the microprocessor which has the control algorithm inherent therein which dictates the control function for each of the devices of the system. The power module also contains the switching power supply which controls the fan speed of the vehicle's blower fan. It also contains various relays which serve to turn the refrigeration or air conditioning system on and off, which serve to turn the system completely on or off, the system being switchable between automatic, off and manual, and it is the point where all the wiring connected to the vehicle and auxiliary devices originates from the power module.

The control module 12 is a unit connected to the power module. The control module contains a display which provides a visual indication of the status of the system, including the preset temperature. This preset or target temperature is the temperature which the operator or user sets and which is to be maintained inside the car or vehicle. The display also shows the status or operating parameters of the fan and air conditioning or refrigeration system _o It also shows the outside temperature in the instantaneous mode (instantaneous operation mode) when that mode is selected. It shows the overall system status when the manual or OFF mode has been selected.

The display is a backlight reverse transmission display, so that the entire display except the characters,

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which are the symbols and alphanumeric representations indicating the functions to be described, is dark or black. The level of backlight illumination can be adjusted in two levels, which occurs automatically when the vehicle's headlights are switched on or off. When the vehicle's headlights are switched on, the backlight illumination is switched to the low or dim level.

The control module contains six buttons or push buttons that are used to configure the system. Two buttons are dedicated to the preset temperature: there is an up arrow button and a down arrow button that are used to move the preset temperature level up or down. The Air Conditioning button selects one of three air conditioning or cooling modes. One of these modes is automatic, in which the air conditioning or cooling system is turned on or off as requested by the microcontroller. If the preset or target temperature is lower than the ambient temperature and cooling is required, the air conditioning or cooling system is turned on. If heating is required, the air conditioning or cooling system is turned off. The second mode or operating mode of air conditioning or cooling is OFF, which means that the air conditioning or cooling system remains off regardless of the temperature conditions _o

The third mode or operation is ON, in which the air conditioning or refrigeration system remains on regardless of the temperature. (The operation of the air conditioning or refrigeration system is interlocked with the operation of the fan; the air conditioning or refrigeration system does not operate if the fan is off.) Even in the event that heating is requested, the air conditioning or refrigeration system remains on, however, in automatic mode, the system will still attempt to maintain the temperature inside the vehicle by turning on the heating. An advantage of this

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The advantage of the &Xgr;&Igr;&Ngr; function is that the heated air can be dried or dehumidified, which is useful for clearing a fogged-up windshield on a damp or foggy day.

The fan button can cycle through four different operating states for the fan. One is Fan Auto, in which the fan is automatically adjusted by the microprocessor depending on the temperature and the control algorithm in sixteen individual steps as required. Another state is OFF, in which the fan is completely turned off. Another state is Fan Low, in which the fan speed is maintained at a constant low speed regardless of the conditions, and the last is Fan High, in which the fan is maintained at a constant high speed regardless of the conditions. There are two other buttons, one of which corresponds to an EXTERNAL state, in which the external or outside temperature is displayed for about 5 seconds instead of the temperature preset on the control module. The other is a "System" button, which allows the user to select one of three basic modes for the entire system: Climate Control, Manual and OFF.

In the Climate Control mode, the system controls the heater, air conditioning, and fan speed to maintain the temperature. The second mode is a manual mode in which control of the heater, air conditioning, and fan speed is returned to the original controls installed in the vehicle by the manufacturer, which are therefore the original equipment and are also called OEM (Original Equipment Manufacturer) controls. The vehicle's original fan speed selector switch is used to control the fan speed, and the vehicle's heater and air conditioning controls are used to control the heater and air conditioning.

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The third mode or operation is OFF. When this mode is selected, all basic components of the system are turned off. This includes closing the heater valve so that no hot water flows into the heat exchanger. The term valve is used here in a general sense to mean a shut-off device. The blower or fan and the air conditioning are both turned off.

An input is provided from the vehicle headlights 14 to the power module 10. There is a current sense wire spliced into each wire that is energized when the vehicle headlights are turned on. The power module senses the turning on of the vehicle headlights and, once the headlights have been turned on, lowers the backlight or backlight level of the control module display.

An external or outside temperature sensor 16 also feeds data into the force module 10. The outside temperature module 16 is located remote from the force module 10 and is preferably located under the front bumper of the vehicle. The sensor 16 includes a temperature sensing integrated circuit (IC) which has a temperature characteristic which can be considered fairly linear from about 30 ⁰ C (20 ⁰ F) below zero to about 50 ⁰ C (120 ⁰ F) above zero. The sensor 16 is housed in a housing which can be attached to the exterior of the vehicle bumper by, for example, explosive riveting or self-tapping screws. The housing is equipped with an air barrier or air insulation which is intended to prevent evaporative cooling from distorting the actual prevailing temperature.

An intake assembly 18 is located in the passenger compartment of the vehicle and is connected to the power module. The intake assembly 18 indicates the temperature prevailing in the passenger compartment. This information is used to determine what actions to take to achieve and maintain the desired preset or target temperature.

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The intake assembly 18 contains two parts, one part is a thermistor holder which is a small multi-part plastic housing mounted in the dashboard of the vehicle. The housing contains a tube which has a small grille on one end which is open to the outside of the passenger compartment. Inside the tube is a thermistor which is connected in series with a circuit located in the power module 10 which allows the power module to electrically read the temperature inside the vehicle. The tube which contains the thermistor is connected by a small hose to the other part of the intake assembly which is the intake fan. This contains a fan cover and a small flat fan (muffin fan) which draws air through the tube and consequently through the thermistor assembly or thermistor holder. This is to avoid stagnant air within the thermistor holder, which would otherwise result in a purely local and perhaps inaccurate reading of the temperature inside the vehicle. Air is thus drawn in from a much wider area of the vehicle compartment, thus providing a more realistic averaged reading of the temperature inside the vehicle. There are a number of other microclimate problems that are solved by the intake assembly, such as self-heating of the thermistor due to the small amount of energy consumed by the thermistor to sense its resistance, and heating of the air in the immediate vicinity of the thermistor due to heating of a black plastic thermistor housing or due to direct heating by the sun.

The cooling or air conditioning (Air Conditioning) refers to the original OEM cooling or air conditioning system of the vehicle. This could be described as a cooling or air conditioning switch because the power module 10 is parallel to the wiring on the OEM air conditioning switch.

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is kept on and in this way the system performs the switching on and off of the air conditioning system. The reason for such an arrangement as opposed to directly controlling the compressor or any other fundamental device of the air conditioning system is that numerous safety systems and safeguards are built in which prevent the system or equipment from running when there is no freon or refrigerant gas in the system or when there is an overheating or undertemperature condition. To avoid short-circuiting or bypassing such safety devices, the air conditioning system is switched on and off by the air conditioning or climate control switch.

A line filter 22 is a device that is connected in series with the wires that lead from the power module 10 to the vehicle's blower fan 24. This line filter 22 is a ring-shaped choke assembly that is potted and serves to suppress noise that occurs as a result of microphony in toroidal windings. The line filter minimizes the electromagnetic hum or radio frequency interference that would otherwise be picked up by the vehicle's AM receiver.

The vehicle's OEM blower fan 24 is used to circulate hot or cold air in the passenger compartment. The speed of this fan is preferably adjusted in 16 individual steps.

The heater valve 26 is a solenoid energized heater valve that is placed in series with the vehicle's original equipment or OEM heater valve, if one exists. The heater valve 26 is a normally open shut-off device, which allows the system of the invention to operate more reliably than if a normally closed shut-off device were used. In the absence of hardware or a device to energize the valve, there is still complete control of the heat by the vehicle's OEM valve, if such an OEM valve exists.

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A coolant threshold thermostat 28 is located in the body of the heater valve. This is an ON/OFF device of the bimetallic strip type, and the function of this thermostatic device is to indicate to the power module whether the coolant has reached or exceeded a certain threshold temperature so that the power module knows that heat is available if heat is required. The purpose of communicating this information to the power module and in particular to the microprocessor is that if heating is required when the fan is set in automatic mode, the blower or fan will not be turned on until heat is available so that only then will warm air be blown into the passenger compartment.

The heater valve 26, like the thermostat, is an ON/OFF device. In other words, it can only be fully open or fully closed. There is a control algorithm which simulates a proportional valve effect, which is achieved by controlling the ratio between the open time and the closed time of the valve, i.e. the duty cycle, within a fixed time period of, for example, 20 s. Within this period of 20 s, the open/closed ratio can be changed in increments of 1.25 s so that a sufficiently constant and predictable amount of heat is available at the heat exchanger. A relatively high blower or fan speed is maintained to achieve good air circulation inside the vehicle without overheating and without exceeding the set point, so that it is not necessary to reduce the fan speed dramatically.

A manual override switch 30 is a switch included in the system in the event that a catastrophic failure of the microprocessor or associated circuits occurs. The switch 30 allows the user to place the system in manual mode

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without having to go through the microprocessor, which is otherwise the case when the manual mode is selected with the system button on the control module.

The following is a brief summary of the above and a brief description of the built-in climate or built-in climate control.

The main or power module 10 of the in-vehicle climate control accepts keypad inputs relating to the selected operating mode and the desired temperature in the passenger compartment of the vehicle. The module compares this information to the actual or actual temperature in the passenger compartment and, by operating both the vehicle's air conditioning and heating controls and the speed of the blower or fan, causes the temperature in the passenger compartment to be maintained as close as possible to the desired preset temperature. The climate control also uses redundant circuitry to isolate major portions of its circuitry when in a mode.

The installation power unit consists of a microcomputer which processes all data and determines the current settings for the blower or fan, the air conditioning relay and the heater valve 26. It also operates the keypad located in the control module 12 and provides inputs to the display located in the control module. In fact, all inputs and outputs to and from the microcomputer are serially shifted data bits to accommodate the large number of bits required. The microcomputer outputs the desired fan speed on four serially shifted bits to a D/A converter. The D/A converter provides an analog stimulus to the fan drive circuit.

The fan drive circuit contains a pulse width modulation (PWM) comparator that generates a constant frequency square wave with a varying duty cycle, the average of which represents the desired fan speed. The FWM comparator controls a FET

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Driver (FET = Field Effect Transistor) which uses a bias voltage of about 26 V DC derived from a bias oscillator and uses tripler circuits to drive the FET output stage. The FET output stage provides a high power square wave which is filtered and then output to the fan motor. The bias oscillator also provides the ramp necessary for the PWM comparator.

The FET output stage receives its power from the vehicle’s battery after appropriate suppression and filtering of voltage surges.

The manual override mode causes the air conditioning control to become transparent to the vehicle controls. In manual mode, the duty cycle for the fan is set to constant ON and both the air conditioning and heater solenoid controls are disabled. The air conditioning control uses two relay contactors wired in series that make up a normally operating relay, whereas the manual override relay is only operating when the system is in manual override mode. This design makes it possible for the air conditioning to be manually controlled even if one relay fails. Similarly, two FETs connected in series are used to control the heater valve. One FET is normally operating while the other FET is only operated in manual override mode. This design makes it possible for the heater to be manually operated even if one FET fails.

The power for all control circuits is derived from the key-operated output of the vehicle's ignition switch. The control or actuation power uses 8 V, which is maintained by a fixed regulator. The signal or logic power is provided by a 5 V regulator. The microprocessor uses a low energy supply regulator that is connected to

the vehicle's battery to ensure that even when the ignition switch is off, the microprocessor is able to store all of the programmed information. When the ignition switch is turned off, and also during a power failure, such as when starting the vehicle, the voltage sensor detects that the supply voltage is about to disappear and issues an interrupt to the microprocessor, forcing the microprocessor to enter a life-sustaining state. After a sufficient time has elapsed after entering the life-sustaining state, the microprocessor is placed in the reset state until power returns. The microprocessor's clock is also stopped during the reset state. In the reset state, the microprocessor is disabled and draws a current of only a few microamperes, which places an insignificant load on the vehicle's battery.

Two important points are made with respect to the invention with reference to FIG. 1. The heater valve 26 is installed in series with the original or OEM heater valve, if one is present, to make support for the climate control system of the invention universal. In addition, and as described in a prior U.S. patent application Serial No. 07/756,034 by Hans Weigert, assigned to the same assignee as the present application, the system is connected to the positive side of the blower fan to enable any individual blower fan characteristics to be neutralized and to enable installation of the climate control system of the invention to be universally implemented and supported in virtually any existing vehicle equipped with an air conditioning and heating system.

The operation of the built-in air conditioning control system in automatic fan mode and automatic climate control mode

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The mode of operation of the invention is as follows;

Using the buttons on the control module 12, the user enters the temperature to be maintained within the passenger compartment. This information is passed to the microcomputer in the power module 10. It reads the passenger compartment temperature via the intake assembly 18, and it also reads whether or not the coolant temperature is above the threshold temperature considered sufficient to provide heat to the passenger compartment. Based on these inputs, the power module 10 issues commands to the various auxiliary devices included in the system to achieve and then maintain the desired set temperature entered by the user. Once the passenger compartment temperature has been determined, it is compared to the preset temperature level entered via the control module 12, and both the direction and magnitude of the difference resulting from the comparison is determined. It determines whether heating or cooling is required and specifically determines how many degrees the difference is in relation to the need to heat or cool, i.e. the number of delta degrees or delta T in relation to the preset or set point.

The control algorithm is selected to be appropriate for one of five basic control states. The five basic control states are: (1) equilibrium or set point, which means that the temperature in the passenger compartment matches the temperature selected as the set point, (2) delta cooling state, which means that the temperature in the passenger compartment is a predetermined number of degrees or less above the set point temperature, (3) full cooling state, which means that the temperature is a fixed number of degrees or more above the desired set point temperature, (4) delta heating state, which means that the ambient temperature or passenger temperature is 0.56 to 5.0 ⁰ C (1 to 9 ⁰ F) cooler than the set point temperature.

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temperature, and (5) full heat, which means that the passenger compartment temperature is 5.6 ⁰ C (10 ⁰ F) or more cooler than the set point temperature. Depending on the range of the control algorithm, the power module dictates that certain steps must be taken. In Delta Cool mode, the air conditioner is turned on, the fan speed is then selected as a function of Delta T, and this is then controlled by the control algorithm. A certain preset is used to initialize the system, and this fan speed preset can be changed depending on conditions. The microcomputer is updated with respect to passenger temperature every 5 s by the intake assembly 18, and based on what happens during each of the successive 5 s periods, the control algorithm is modified.

This is an example of closed loop control in the control algorithm. In heating mode, Delta heating mode, the fan speed is selected and controlled in the same way and the heat in the heat converter is controlled by the heating valve. The heating valve is an on/off or open/closed device, but the valve is made a proportional valve by changing the duty cycle for the time the valve is open and closed.

There are certain smoothing features built into the control algorithm with the intention of making the operation of the device or appliance aesthetically pleasing in that the passenger compartment occupants do not experience abrupt changes in heating or cooling, nor abrupt changes in fan speed, nor abrupt changes from heating mode to cooling mode. One of these smoothing features is a 10 second or 2 time period delay during which one cannot enter heating mode if the system was previously in cooling mode. This is arranged so that

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because if the set point is exceeded by the cooling mode, it is undesirable to supply heat to the passenger compartment to return to the set or target point, because such an operation is perceived as uncomfortable by the vehicle occupants. Instead, the system waits a certain number of seconds until the temperature slides back to the set point on its own, or perhaps even into the delta cooling zone.

FIG. 2 shows the basic block diagram of the control head, which is part of the control module 12, including inputs from the microprocessor 40 located in the force module 10. A liquid crystal display (LCD) display module 42 receives inputs from the microprocessor 40. As shown in FIG. 3, an internal shift register 45 is provided which receives data from the microprocessor 40 which is used to drive or control the LCD display 40. A keypad 48 is connected to and controls a shift register 46, with the data from the shift register 46 then entering the microprocessor 40. The microprocessor 40 is a National Semiconductor COP 344C device which can be programmed in a conventional manner to perform the functions specified for the system of the invention. One such algorithm is described in detail below.

The microprocessor 40 receives inputs from an A/D converter 50 which converts the analog output of the outside temperature sensor 16 either to degrees Celsius or to degrees Fahrenheit via a divider 52 and the analog output of the inside or passenger compartment temperature sensor 18. These sensors 16 and 18 are connected as inputs to the A/D converter 50. A shift register 56, shown in FIG. 4, is connected to an output line of the microprocessor 40 and controls the air conditioning or heating mode minimum fan speed selection, the D/A converter, the air conditioning relay, the heater solenoid and the manual mode relay.

FIGS. 3 and 4 are block diagrams of separate parts of the force module. FIG. 3 also contains the block diagram of the control module. A voltage sensor 54 is part of the feedback

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setting circuit and freezes the clock in the microprocessor when the vehicle ignition is turned off so that the data in the microprocessor is not lost and the microprocessor will operate in the same mode when the vehicle is restarted. The voltage sensor 54 is connected to the microprocessor as shown in FIG. 3. A display light 60 is connected to and driven by a display power supply 58 which display power supply receives an input from the vehicle headlights 14.

A clock generator 55 provides clock signals to the microprocessor 40 and is connected to the reset line on the voltage sensor 54.

A 12 V vehicle battery is connected via a resistor 59 to the cathode of a diode 61 and is further connected to an input of a 5 V energy sensor 100, which in turn is connected to the microprocessor 40.

As can be seen from FIG. ₀ 3 , the keypad 48, the shift register 46, the display 44, the LCD display driver 42 with its internal shift register 45 and the display illumination 60 form the control module 61 which is accessible to the driver under normal driving conditions.

As can be seen from FIG. 4, the fan driver circuit 62 includes a number of different components, which are shown in detail.

The fan driver circuit 62 receives its input from the shift register 56 which is converted in a D/A converter 64. The output of the D/A converter is connected to one input of a two input PWM (pulse width modulation) comparator 66 and the other input of the comparator 66 is from a bias oscillator ramp generator 68. The output of the PWM comparator 66 is connected to one input of a FET driver 69 and a second input of the FET driver 69 is from a tripler 70. The tripler 70 receives its input from the bias oscillator ramp generator 68 with the FET driver 69 biased at 26V.

The output of the FET driver 69 is fed to one input of a two-input output FET 72, the other input of which is powered by an input supply circuit 74. The input supply circuit receives its input power from the vehicle power which is fed to the supply input of the output FET 72 via a surge suppressor 75 and a filter 76. The output FET 72 outputs its power via a filter mediator 78 to control the motor _o

The manual override switch 30 is shown connected to the heater solenoid driver 80 as well as to the climate relay 82, both of which also receive inputs from the shift register 56 controlled by the microprocessor 40.

The manual override mode causes the climate control to become transparent to the vehicle controls. In manual mode, the duty cycle delivered to the fan is set to constant ON and both the climate solenoid control and the heater solenoid control are disabled. The climate control makes use of two relay contactors 90 and 92 connected in series with one relay 90 normally operating, whereas the manual override relay 92 only operates in manual override mode. In this way, it is possible to manually control the climate control even if one relay fails. Likewise, FET 93 and FET 94 are connected in series with one another and are used to control the heater valve. One FET is normally operated or operated, whereas the other FET is only operated or operated by the manual override mode. This makes it possible to manually operate the heater even if one FET fails.

Power for all control circuits is derived from the key operated output of the vehicle ignition switch 95 which is connected through a surge suppressor 96 to a fixed regulator 97. The regulator 97 provides 8 volts of control power for the system. Signal or logic power is provided by a 5 volt regulator 100 connected to the

-25-

output of the 8-volt regulator 97. The microprocessor makes use of a low consumption regulator connected to the vehicle battery to ensure that even when the ignition switch is off, the microprocessor·* continues to hold all programmed information in memory.

The following is a description of set point tracking. Moving the set point a number of degrees requires depressing the appropriate set point button the same number of times. Tracking simply requires that the appropriate set point button be held down until the display shows the desired set point temperature.

Pressing the Setpoint Up or Setpoint Down button will cause an immediate one degree change in the setpoint temperature. After a delay of about one second, the display will track in the selected direction at about a 1/2 second rate.

Tracking will stop when the setpoint button is released. Tracking will also stop when the upper or lower setpoint temperature limit is reached. The delay and tracking rate time can be adjusted if required under the control of the microprocessor 40.

Description of the temperature control algorithm

Previous information may be repeated, but this information is provided in advance to provide a comprehensive identification of the temperature control algorithm.

The temperature in the passenger compartment of the vehicle is achieved by controlling the fan speed, by switching the air conditioning on and off and by means of a normally open hot water control valve which regulates the amount of hot water flowing through the vehicle's heat exchanger ₀ A temperature-sensitive device is used.

to measure the ambient temperature in the passenger compartment. The ambient temperature in the passenger compartment is measured every 5 (five) seconds.

Fan speed control &iacgr;

Two minimum fan speeds are included in the system. The minimum fan speed when air conditioning is not required is set at approximately 25% of full fan speed. The minimum fan speed when air conditioning is required is set slightly higher at approximately 3396 of full fan speed. Provision is made for individual selection of higher minimum fan speeds for both conditions.

The fan speed can be set to any of sixteen (16) different speeds. The minimum fan speed is fan speed ¹¹⁰ ", whereas the maximum fan speed is fan speed 15". Fan speeds "1" through "14" are evenly spaced between the minimum and maximum fan speeds. Since the minimum fan speed in air conditioning is higher than the minimum fan speed in heating, the fan speed increment in air conditioning is slightly smaller.

The fan can be placed in four (4) operating conditions: OFF, LOW, HIGH and AUTOMATIC. The first three operating conditions either turn the fan off or run it at a fixed predetermined speed. The automatic operating condition allows the microprocessor to determine the fan speed based on heating or air conditioning requirements.

Heating water flow control:

The hot water flow through the heat exchanger is controlled over a period of twenty (20) seconds. This 20 second period is divided into increments of 1.25 seconds each _. The hot water valve may be open for the entire 20 seconds, closed for the entire 20 seconds, or open from 1.25 seconds to 18.75 seconds in increments or steps of 1.25 seconds.

The selection of the length of time the hot water valve is open during a 20-second period is

-27-

determined by the fan speed and heating requirements. The microprocessor determines the opening time of the hot water valve when heat is called for. The hot water valve is closed when no heat or air conditioning is called for or when the blower or fan is OFF when heat is called for. In the first two conditions, the air conditioning is either constantly OFF or constantly ON ₀ The automatic operating condition allows the microprocessor to determine the air conditioning requirements based on the cooling requirements.

Heating delay:

Heating or cooling of the passenger compartment is determined by measuring the ambient temperature in the passenger compartment of the vehicle and comparing this measured temperature with the desired or set point temperature. If the set point temperature is lower than the measured ambient temperature in the passenger compartment, air conditioning is required. If the set point temperature is higher than the measured ambient temperature in the passenger compartment, heating is required.

The difference between the set point temperature and the measured ambient temperature in the passenger compartment is called "Delta Temp".

When cooling is required and the air conditioning is operating in automatic mode, the microprocessor will run the air conditioning continuously until Telta-Temp is zero. The air conditioning will then shut off. However, it is possible for an overshoot condition to occur where the measured ambient temperature in the passenger compartment becomes slightly cooler than the set point temperature.

Although this condition would normally require heating, the passenger compartment may warm up somewhat on its own in a few seconds due to the warmer outside air temperature. Therefore, to avoid unnecessary use of heating, the hot water valve will not be opened if the climate control system has previously been operating in cooling mode until a predetermined time has elapsed.

-28-

Delay time. This delay time may preferably be set to ten (10) seconds.

Temperature control states:

The temperature control is divided into five specific areas or "states" based on the difference between the measured ambient temperature in the passenger compartment and the set point temperature. A brief overview of each of these five (5) states is provided below. These states are:

Condition Description

0 Full cooling

1 Delta cooling

2 Balanced state

3 Delta heating

4 Full heating

State 0 (Full cooling):

The temperature control is in state 0 when the measured ambient temperature in the passenger compartment is five (5) or more degrees higher than the set point temperature. In automatic fan mode, the fan speed is set to maximum. In automatic air conditioning mode, air conditioning is continuous. The hot water valve is energized and therefore blocks the flow of hot water.
State 1 (Delta cooling):

The temperature control is in State 1 when the measured ambient temperature in the passenger compartment is one (1) to four (4) degrees higher than the set point temperature. In the automatic fan mode, the fan speed is related to the difference between the measured ambient temperature in the passenger compartment and the set point temperature, with the smaller the temperature difference, the lower the fan speed. In the automatic climate control mode, the climate control is always on. The hot water valve is energized so that all water flow is blocked. State 2 (balanced state):

The temperature control is in state 2 when the measured ambient temperature in the passenger compartment is equal to the

-29-

set point temperature. In automatic fan mode, the fan speed is gradually reduced until either the minimum fan speed is reached or the measured ambient temperature in the passenger compartment is no longer equal to the set point temperature. In automatic climate control mode, climate control is OFF ₀ The hot water valve is energized so that all hot water flow is blocked. State 3 (Delta heater):

The temperature control is in state 3" when the measured ambient temperature in the passenger compartment is one (1) to nine (9) degrees lower than the set point temperature. In automatic fan mode, the fan speed is related to the difference between the measured ambient temperature in the passenger compartment and the set point temperature, with essentially the smaller the temperature difference, the lower the fan speed."

In conjunction with the fan speed control, the hot water valve is opened for specific periods of time to control the amount of water flowing to the heat exchanger and thereby help control the ambient temperature in the passenger compartment. However, when the fan is OFF, the hot water valve is closed. In automatic climate control mode, climate control is OFF.
State 4 (Full heating):

The temperature control is in state 4 when the measured ambient temperature in the passenger compartment is ten (10) or more degrees lower than the set point temperature. In automatic fan mode, the fan speed is set to maximum speed. In automatic climate control mode, climate control is OFF. The hot water valve energization is turned off, allowing full flow of hot water through the heat exchanger.
State table entries:

As previously stated, the air conditioning has three (3) operating modes:
OUT OF,
ON and
AUTOMATICALLY.

-30-

In contrast, the blower or fan has four (4) operating modes:

OUT OF,

A,

LOW and

AUTOMATICALLY.

Combining all possible fan and air conditioning operating modes together, one obtains twelve (12) possible sets of fan and air conditioning controls for each operating state. Five state tables have been prepared that fully define the operation of the air conditioning, fan and hot water valve in each state.

Table entry symbols are listed below. Note that hot water flows or flows when the hot water valve is OFF (no energization) and that hot water does not flow when the hot water valve is ON (energization).

symbol

ACMIN
CNTL
Delta Temp

FAN+2
FAN-3
HTML

OFF
ON
VLV

Description

Air Conditioner

Minimum fan speed for air conditioning

Operation under computer control

Difference between measured passenger compartment and

Set point temperature

Blower/Fan

Increment fan speed by two steps

Decrement fan speed by three steps

Minimum fan speed for heating or none

Air conditioning

Maximum fan speed

Fan, air conditioning or hot water valve OFF

Fan, air conditioning or hot water valve ON

Hot water valve

-31-

Full cooling - state 0

AC

OUT OF

A CAR

FAN = MAX FAN = MAX

AUTO AC = OFF AC = ON

VLV = ON VLV = ON

FAN = MAX FAN = MAX

HIGH AC = OFF AC = ON

VLV = ON VLV = ON

FAN = HTMIN FAN = ACMIN

LOW AC = OFF AC = ON

VLV = ON VLV = ON

FAN = OFF FAN = OFF

OFF AC = OFF AC = OFF

VLV = ON VLV = ON

FAN = MAY AC = ON VLV = ON

FAN = MAX AC = ON VLV = ON

FAN = ACMIN AC = ON VLV = ON

FAN = OFF AC = OFF VLV γ ON

Annotation:

1o Ambient temperature 2.8 ⁰ C (5 ⁰ F) or more above the

Setting point
2o Hot water solenoid valve closed (energized): VLV = ON

3. Temperature measurement rate = 5 s

4. Minimum air conditioning ON fan speed: FAN = ACMIN 5γ Minimum air conditioning OFF fan speed: FAN = HTMIN

-32-

Delta Cooling - Condition 1 AC

FAN FROM A CAR

FAN = CNTL FAN = CNTL FAN = CNTL AUTO AC = OFF AC = ON AC = ON VLV = ON VLV = ON VLV = ON

FAN = MAX FAN = MAX FAN = MAX HIGH AC = OFF AC = ON AC = ON VLV = ON VLV = ON VLV = ON

FAN = HTMIN FAN = HCMIN FAN = ACMIN LOW AC = OFF AC = ON AC = ON VLV = ON VLV = ON VLV = ON

FAN = OFF FAN = OFF FAN = OFF OFF AC = OFF AC = OFF AC = OFF VLV = ON VLV = ON VLV = ON

Remarks:

1. Ambient temperature 0.6 to 2.2 ⁰ C (1 to 4 F) above the set point

2. Hot water solenoid valve closed (energized): VLV = ON

3. Temperature measurement rate = 5 s

4. Minimum air conditioning ON fan speed: FAN = ACMIN

5. Minimum air conditioning OFF fan speed: FAN = HTMIN 6γ Auto mode fan control (previously in state 1 or 2):

a. If Delta-Temp(new) ^ Delta-Temp(old);

FAN ϳ FAN + 2 up to FAN = MAX

b. If Delta-Temp (new) < Delta-Temp (old):

FAN = FAN - 3 down to FAN = ACMIN

7. Auto mode fan control (previously in state O, 3 or 4) FAN = 3 x Delta Temp

·*
&bull;&igr; ·· ·« *% «· &bull; &bull;
* &diams; « ·· -33-

Balanced state - state 2

AC

FAN OFF

FAN = FAN AUTO AC = OFF
VLV = ON

FAN = MAX HIGH AC = OFF
VLV = ON

FAN = HCMIN LOW AC = OFF
VLV = ON

FAN = OFF AC = OFF
VLV = ON

SIN

FAN = FAN - 2
AC = ON
VLV = ON

FAN = MAX AC = ON VLV = ON

FAN = ACMIN AC = ON VLV = ON

FAN = OFF AC = OFF VLV = ON AUTO

FAN = FAN AC = OFF VLV = ON

FAN = MAX AC = OFF VLV = ON

FAN = HCMIN AC = OFF VLV = ON

FAN = OFF AC = OFF VLV = ON

Remarks:

Ambient temperature = set point

2. Hot water solenoid valve closed (energized): VLV = ON

3. Temperature measurement rate = 5 s

4. Minimum air conditioning ON fan speed: FAN = ACMIN

5. Minimum air conditioning OFF fan speed: FAN = HTMIN

6. Auto mode fan control:

FAN m FAN - 2 down to FAN = ACMIN or HTMIN

-34-

DeIta heater - condition

AC

OUT OF

A

AUTOMOBILE

HIGH

LOW

FAN
AC-C =
VLV

FAN
AC-C =
VLV

FAN
AC-C =
VLV

FAN
AC-C =
VLV

= CNTL
OUT OF
= CNTL

= MAX
OUT OF
= CNTL

= ATMIN
OUT OF
= CNTL

= OFF
OUT OF

= SIN

FAN AC : VLV

FAN AC = VLV

FAN AC = VLV

FAN AC = VLV

= CNTL ON = CNTL

= MAX ON = CNTL

= ACMIN ON = CNTL

= OFF

OUT OF

-- A

FAN AC = VLV

FAN AC = VLV

FAN AC = VLV

FAN AC = VLV

= CNTL OFF = CNTL

= MAX OFF = CNTL

= HTMIN OFF = CNTL

= OFF

OFF = ON

Remarks:

^5V

(1 to 9°F) below the

1. Ambient temperature 0.6 to setting point

2. Fan running: Hot water solenoid valve controlled:

VLV = CNTL

3. Fan Off: Hot water solenoid valve closed (energized)

VLV = ON

4. Tax rates:

a. Temperature measurement rate = 5 s

b. Valve control period rate = 20 s

5. Minimum air conditioning ON fan speed: FAN = ACMIN

6. Minimum air conditioning OFF fan speed: FAN = HTMIN

7. Auto mode fan control (previously in state 1 or 2);

a. If Delta- Temp (new) ^ Delta-Temp (old): FAN = FAN + 2 up to FAN = MAX

b _o If Delta-Temp (new) < Delta-Temp (old): FAN = FAN - 3 up to FAN - ACMIN

-35-

8. Auto mode fan control (previously in state 0, 3 or 4):

FAN = 3 x Delta Temp

9. Fan control (fan running):

a. If FAN = MAX and Delta-Temp (new)^ Delta-Temp (old): Valve open (new) = Valve open (old) + 2.5 s

b. If FAN = ACMIN or HTMIN

and Delta-Temp (new) < Delta-Temp (old); Valve open (new) = Valve open (old) - 2.5 s

c. Initial valve opening time = 1.25 x Delta-Temp + 2.5 s

10. Heating delay:

Heating start period delayed by 10 s if cooling was previously requested.

-36-Full heating - condition

AC

PAN

OUT OF

A

AUTOMOBILE

AUTOMOBILE FAN = MAX
AC = OFF
VLV = OFF &bull;
# FAN = MAX
AC = ON
VLV = OFF FAN = MAX
AC = OFF
VLV = OFF HIGH FAN = MAX
AC = OFF
VLV = OFF FAN = MAX
AC = ON
VLV = OFF FAN = MAX
AC = OFF
VLV = OFF LOW FAN = HTMIN
AC = OFF
VLV = OFF FAN » ACMIN
AC = ON
VLV = OFF FAN = HTMIN
AC = OFF
VLV = OFF OUT OF FAN = OFF
AC = OFF
VLV = ON FAN = OFF
AC = OFF
VLV = ON FAN = OFF
AC = OFF
VLV = ON Remarks

1. Ambient temperature 5.6 ⁰ C (1O ⁰ F) or more below

of the setting point.

2. Fan running: Hot water solenoid valve open (de-energized):

VLV =9 OFF

3. Fan off: Hot water solenoid valve closed (energized):

VLV = ON

4γ Temperature measurement rate = 5 s

5. Minimum air conditioning ON fan speed: FAN = ACMIN

6. Minimum air conditioning OFF fan speed: FAN = ATMIN.

&bull; · · · aft

-37-

The built-in climate control system according to the invention has been described above in detail with reference to a preferred embodiment. Modifications to the system are possible within the scope of the skilled person. Such modifications also fall within the scope of protection.

Claims (12)

ftt -38- Protection claims 1. Universal retrofit system for climate control of a vehicle passenger compartment for subsequent installation in any of a variety of liquid-cooled vehicles that already have an air conditioning and/or heating system with a heat exchanger located in a coolant circuit through which the coolant flows as original equipment to supply heat to the passenger compartment, which retrofit system contains: a control module (12) suitable for mounting in the passenger compartment in such a way that it is accessible to the driver of the vehicle for easy operation, an intake unit (18) arranged at a location close to the passenger compartment for determining the temperature in the passenger compartment, a power module (10) which is electrically connected to the control module and is connected to the intake assembly for receiving electrical signals relating to the ambient temperature in the passenger compartment and which contains a microprocessor (40) which controls an air conditioning and heating system for automatically regulating the climate of the passenger compartment of the vehicle, and a heating valve (26) which is suitable for installation in the coolant circuit and responds to the microprocessor (40) to regulate the coolant flow to the heat exchanger, which heating valve (26) is an element of the universal retrofit system and is to be installed regardless of whether the original equipment already contains a heating valve or not. 2. Universal retrofit system according to claim 1, wherein the vehicle includes an original heater valve (originally installed heater valve or so-called OEM heater valve) and the (retrofittable) heater valve (26) is connected in series with the original heater valve, the original heater valve being controllable such that it is fully open when the climate control system is in operation. -39- 3. Universal retrofit system according to claim 1 or 2, wherein the time during which the (retrofittable) heating valve (26) is open or closed can be controlled by the climate control system and thus by the microprocessor (40). 4. Universal retrofit system according to one of the preceding claims, in which the retrofit system has a manual override condition, the (retrofittable) heater valve (26) is designed such that it is normally open to ensure that in the event of failure of the climate control system and activation of the manual override condition, refrigerant can flow into the heat exchanger to control the temperature in the passenger compartment. 5. Universal retrofit system according to one of the preceding claims, wherein the control module (12) contains a display or a display (44) which is connected to the microprocessor (40) for controlling the climate control system. 6. Universal retrofit system according to one of the preceding claims, wherein the vehicle contains a water-cooled engine. 7. Universal retrofit system according to one of the preceding claims, in which it contains a device for fastening the control module (12) in an area easily visible to the driver and within the reach of the driver. 8. A universal retrofit system according to any preceding claim, wherein the microprocessor (40) includes a closed loop system or a control system that enables the climate control system to achieve a desired value. 9. Universal retrofit system according to one of the preceding claims, in which an air conditioning switch is provided, which is connected to an air conditioning system already existing in the vehicle ·· M »· »4 »* «tit -40- is electrically connected in parallel. 10. A universal retrofit system according to any preceding claim, wherein the intake assembly (18) includes a thermistor holder and further includes a fan assembly for drawing air through the thermistor holder to average the sensed air temperature and reduce the response time of the thermistor. 11. A universal retrofit system according to any preceding claim, further comprising a refrigerant threshold temperature thermostat responsive to an increased refrigerant temperature and connected to the microprocessor to allow requested heating in the passenger compartment. 12. The universal retrofit system of claim 11, further comprising a device for preventing the fan in the vehicle from blowing air until the refrigerant threshold temperature thermostat is activated.