CA1339274C - Temperature controller for car air conditioner - Google Patents
Temperature controller for car air conditionerInfo
- Publication number
- CA1339274C CA1339274C CA000546284A CA546284A CA1339274C CA 1339274 C CA1339274 C CA 1339274C CA 000546284 A CA000546284 A CA 000546284A CA 546284 A CA546284 A CA 546284A CA 1339274 C CA1339274 C CA 1339274C
- Authority
- CA
- Canada
- Prior art keywords
- air
- temperature
- air conditioner
- control system
- control
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/00642—Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
- B60H1/00735—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models
- B60H1/00807—Control systems or circuits characterised by their input, i.e. by the detection, measurement or calculation of particular conditions, e.g. signal treatment, dynamic models the input being a specific way of measuring or calculating an air or coolant temperature
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/00642—Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
- B60H1/00814—Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation
- B60H1/00821—Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation the components being ventilating, air admitting or air distributing devices
- B60H1/00835—Damper doors, e.g. position control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60H—ARRANGEMENTS OF HEATING, COOLING, VENTILATING OR OTHER AIR-TREATING DEVICES SPECIALLY ADAPTED FOR PASSENGER OR GOODS SPACES OF VEHICLES
- B60H1/00—Heating, cooling or ventilating [HVAC] devices
- B60H1/00642—Control systems or circuits; Control members or indication devices for heating, cooling or ventilating devices
- B60H1/00814—Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation
- B60H1/00878—Control systems or circuits characterised by their output, for controlling particular components of the heating, cooling or ventilating installation the components being temperature regulating devices
Abstract
In an air conditioner installed on a motor vehicle, a temperature control system of a type in which detected temperature value of air discharged from the air conditioner is controlled convergently to a desired temperature value by regulating thermal exchange capability of the air conditioner includes an arithmetic apparatus for arithmetically determining and updating sequentially a deviation of the actual heat exchange capability from a requisite heat exchange capability in accordance with a difference between the detected temperature value and the desired temperature value, control apparatus for performing regulation of the heat exchange capability on the basis of the deviation, and decision apparatus for enabling the control apparatus to fetch the deviation every time predetermined conditions are satisfied, wherein the convergent control is effectuated by correspondingly modifying the heat exchange operation performed intermittently.
Description
1339~74 BACKGROUND OF THE INVENTION
The present invention relates to an air conditioning apparatus for a motor vehicle which is conventionally referred to as the car air conditioner.
5 More particularly, the invention is concerned with a temperature control system suited preferably for use in the car air conditioner of a reheat-air mix type.
The air conditioning apparatus for a motor vehicle employed in the early stages was of a separate 10 type in which a cooler and a heater were operated independently of each other. In recent years, an air conditioner of a unitary structure referred to as the reheat-air mix (blend) type air conditioner has been developed arld is now used extensively. In this type of 15 air conditioner, temperature control can be performed continuously from cooling to warming mode to maintain --the intra-car temperature at a predetermined value regardless of a wide change in the outside temperature.
Besides, the air conditioner can enjoy excellent tem-~0 perature control in a continuous manner and can arovide moisture removing capability, to further advantage.
A typical one of the reheat-air mix type air conditioners for motor vehicles or cars is known, for example, from Japanese Patent Application Laid-Open No.
25 136509/1983 (~P-A-58-136509) which corresponds to U. S.
Patent No. 4,456,166. In the discharge air *
1 temperature control of this prior art air conditioner, a difference between the actual temperature Td of the discharged air and a desired temperature Tdo to be attained is derived to determine the desired degree of opening ~am of an air mixing or blend door, wherein the control is so performed that a voltage value tapped from a feed back potentiometer may assume a value correspond-ing to the desired opening ~am.
As will be noted, in the prior art air condi-tioner of the type under consideration, a sensor suchas a feedback potentiometer is employed for detecting the opening of the air blend door, the reason for which - may be explained by adoption of such arrangement in which the discharge air temperature control is accom-plished by deriving the difference between the desireddischarge temperature Tdo and the actual discharge temperature Td through direct comparison of these tem-peratures and controlling the opening of the air mixing or blend door so that the temperature difference (Tdo -Td) approaches or converges to zero.
However, notwithstanding of the fact that theopening of the air blend door, a mechanical quantity, can vary within a relatively short time ~within about l second or less), the air temperature at the discharge port can vary only with a large delay in response (about several seconds to several ten seconds) because of influence exerted by the thermal capacity o~ passage walls (walls of ducts and the like) in addition to the 1~39274 1 influence of the delay involved in the response of the discharge temperature sensor itself.
Under the circumstance, when the control system having the delay in response is to be operated with stability and with high-speed response, as occasion requires, it is necessary to detect the opening of the air blend door and control it so that the door can assume constantly the proper state or position. To this end, a feedback potentiometer is employed as in the case of the prior art temperature control system described above.
With the arrangement in which the feedback - potentiometer is employed as the sensor for detecting the degree of opening of the air blend door, an arithmetical determination of the desired opening ~am, processing of the voltage signal produced by the door opening sensor and other processing are required in the course of the control process. Further, since correction must be made on the possible nonuniformity in the positional relationship between the door opening sensor and the air blend door, the control procedure becomes ve ry complicated, which also means that when a microcomputer control is adopted, the program area is correspondingly increased, giving rise to a problem. sesides~ assembling and mounting of a linkage for interlinking the opening sensor and the air blend door with each other, adjust-ment thereof and other steps required for the setup Qf the system are naturally accompanied with high - 13392~4 1 expenditure, which gives rise to another problem.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an inexpensive discharge temperature control system of a simplified structure, high reliability and improved control accuracy by adopting an arrangement in which the discharge temperature ~Td), the final target item to be controlled, is controlled straight-forwardly and which allows the door opening sensor for the air blend door to be omitted while improving the response capability and stability of the controlsystem.
The abovementioned object can be accomplished by adopting at least one of the operational conditions or criteria mentioned below:
(a) For a time of several seconds to several ten of seconds following immediately the opening control of the air blend door, the control output of the control system is interrupted temporarily in view of an inevitable delay involved in generation of the discharge temperature sensor output signal in response to the temperature of the current air stream as discharged.
(b) The output state of the discharge temperature sensor in which the output signal has a large slope as a function of time, i.e. the temperature detected by the discharge temperature sensor changes from time to time, the control output of the control system is 39~4 1 interrupted temporarily, since this state can be regarded as the transient state of the whole system including the mechanical and aerodynamic systems.
(c) Change in the desired discharge temperature (Tdo) brought about by the operator or driver requires the response of the control system without delay.
Accordingly, the control system is released from the temporary stoppage state.
(d) When the actual discharge temperature (Td) varies beyond the desired discharge temperature (Tdo) as the result of operation of the air blend door, the control system is released from the temporary stoppage state so as to make response without delay.
(e) When the effect of the control output for operating the air blend door as reflected on the dis-charge temperature is insufficient (suppose, for çxample, such a situation in which the discharge temper-ature is not changed because the air blend door is not moved at all due to a balanced state estahlished between the spring force applied to the door and the force applied by the actuator even when more or less amount of the atmospheric air is introduced into the actuator with a view to raising the discharge temperature in the state where the maximum negative pressure is applied to attain the maximum cooling), the control system is released from the temporary stoppage state for the purpose of obtaining the satisfactory response.
(f) When a differencc between the desired discharge 13392~4 1 temperature (Tdo) and the actual discharge temperature (Td) is s~laller than a predetermined temperature difference value (~T), no control output is produced, because the above state means that the desired discharge temperature is realized.
(g) When ¦Tdo - Td¦ > ~T, the control quantity (control output or command) is determined as follows:
when Tdo - Td > 0, then Tdo = Td - ~T
when Tdo - Td < 0, then Tdo = Td +(-~T for thereby assuring continuous (smooth) increasing/decreas-ing of the control quantity.
(h) The actual control quantity is corrected on the basis of the value determined as mentioned in the paragraph (g) for thereby compensating for the non-linearity of change in the discharge temperature inresponse to the change in the control quantity for the air conditioning unit.
(i) Difference in the air flow (due to difference in pressure) between the atmospheric pressure and the negative pressure applied to the negative pressure actuator is corrected.
(j) When the desired discharge temperature Tdo is changed, the control output quantity is increased only once for the purpose of enhancing the feeling of ~5 occupants to the response of the control system.
By adopting the operational criteria or conditions (a) to tj) mentioned above, there can be realized a control system having high stability and 133927~
high response speed without using the opening sensor for the air blend door.
In other words, since the control of the means such as the air blend door for regulating the heat exchange capa-bility is performed intermittently in timing with the delayinvolved in the air temperature detection at the discharge port, the air conditioner can be operated stably without resorting to the control by using the door opening sensor.
According to the invention there is provided in an air conditioner installed on a motor vehicle having a temperature control system of a type in which a detected temperature value of air discharged from the air conditioner is controlled convergently to a desired temperature value by regulating a thermal exchange capability of the air condi-tioner through operation of an air blend door, said controlsystem comprising: arithmetic means for arithmetically determining and updating sequentially a deviation of the actual heat exchange capability from a requisite heat exchange capability in accordance with a difference between the detected temperature value and the desired temperature value;
control means operative in response to updated arithmetical deviations to regulate the heat exchange capacity by controlling operation of said blend door on a repeating basis;
decision means for determining whether or not an inhibit signal is connected to said control means and inhibits a control of operation of said blend door by said control means for a period of time immediately after outputting a control signal is produced; means for producing an inhibit signal as a ~ 1339274 result of a decision by said decision means; and means for suppressing production of said inhibit signal according to an operational condition of said air conditioner.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a view showing schematically an arrangement of a typical air conditioner for a motor vehicle to which an automatic temperature control system according to an embodiment of the present invention is applied;
Fig. 2 is a view for illustrating operation of the system according to an embodiment of the invention;
Figs. 3 and 4 are views for illustrating some steps shown in Fig. 2 in more detail; and Fig. 5 is a view for illustrating the discharge temperature control characteristic of a typical air conditioning unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, the present invention will be described in detail by referring to the annexed drawings which 1~39274 1 show a temperature control system for a car air condi-tioner according to an exemplary embodiment of the invention.
Fig. 1 shows schematically a general arrange-ment of a car air conditioner provided with a temperaturecontrol system according to an embodiment of the inven-tion. In the figure, an air conditioning unit 10, an evaporator 11 and a heater core 12 are, respectively, of conventional structures. As the elements which partake directly in the discharge air temperature control taught by the invention, there can be mentioned an air blend (mixing) door 1, a negative pressure (vacuum) ~ctuator 2, an on/off valve 3, a three-way valve 4, a discharged air temperature sensor 5 and a controller 6.
An intra-car (interior) temperature setting unit 7, an atmospheric (exterior) temperature sensor 8, an intra-car temperature sensor 9 and others are also connected to the controller 6 although they bear no direct relevance to the control proposed by the present inven-tion.
Next, operation in general of the illustratedsystem will be described.
The controller 6 includes a microcomputer and fetches a signal Ts tapped from the intra-car temperature setting unit 7, a temperature signal Ta produced by the atmospheric temperature sensor 8, a temperature signal Tr produced by the intra-car temperature sensor 9 and other parameters, if any, to thereby determine 133927~
l arithmetically a desired (target) discharge temperature Tdo and control various members (not shown) participat-ing in the control of the air conditioner.- Among others, the control of the air blend door 1 is performed in such a manner in which the negative pressure actuator 2 is operated under the control of the controller 6 through the on/off valve 3 and the three-way valve 4 which in turn are controlled in response to signals Vs and V3 produced by the controller 6, whereby the operating position of the air blend door l is correspondingly established.
More specifically, the three-way valve 4 is first connected to a negative pressure source in response to the signal V3. Subsequently, the on/off valve 3 is opened for a predetermined time in response to the signals Vs. Thus, a negative pressure is introduced into the negative pressure actuator 2, whereby the air blend (mixing) door 1 is displaced toward the cooling position by an angle of the magnitude corresponding to the operating time duration of the on/off valve 3, resulting in that the actual discharge temperature is lowered. Reversely, when the three-way valve 4 is so changed over as to communicate with the atmosphere with the on/off valve 3 being subsequently operated to thereby allow the atmospheric air to be introduced into the negative pressure actuator 2, the air blend door 1 is displaced toward the warming side, as the result of which the output temperature rises. The i~ 1339274 1 actual discharge temperature Td of the air discharged through an outlet port OUT of the air conditioner is detected by the discharged air temperature sensor 5 whose output signal is inputted to the controller 6 to be utilized in the arithmetic determination of the desired discharge temperature Tdo. The signals V and V3 resulting from the above calculation are outputted from the controller 6.
Next, arithmetic operation and control procedure performed in this illustrated system will be elucidated in conjunction with Fig. 2 which illustrates the control procedure in a so-called program analysis diagram (PAD in abbreviation).
Referring to Fig. 2, the optimum desired discharge temperature Tdo is arithmetically determined at a step 2.1 on the basis of the aforementioned intra-car set temperature Ts, the atmospheric temperature Ta, the actual intra-car temperature Tr and other parameters.
At the subsequent step 2.2, the actual discharge tem-perature is determined on the basis of the signal Td available from the discharge temperature sensor 5. So far as the steps 2.1 and 2.2 described above are concerned, the control procedure is the same as that of the conventional air conditioner controlling system.
At a step 2.3, the timing at which the control signal is to be outputted is determined. In actuality, this step is a looped-back subroutine in which the operational conditions (a) to (e) described hereinbefore 1 are evaluated, and a value "Yes" is set at the flag "Stop" at the time when the control output is to be stopped temporarily.
At the following step 2.4, the content of the flag "Stop" is checked. When the value "Yes" is set at this flag, the step 2.1 is regained without executing any processing. On the other hand, when the content of the flag "Stop" is found to be "No", the control is transferred to a subsequent step 2.5 for releasing the control system from the temporary stoppage state.
At a step 2.5, a control output or command value indicative of the magnitude of displacement for which the air blend door 1 is to be moved is arithmeti-cally determined on the basis of the desired discharge temperature Tdo and the actual discharge temperature Td in accordance with the aforementioned operational conditions or criteria (f) to (j).
When the control command or output value is zero, no processing is executed at the next step 2.6 because no control output quantity is required to be produced. Only when the control command value is not zero, a control output signal corresponding to the control command value is produced for controlling the displacement of the air blend or mixing door 1.
The sequence of the individual steps described above is repeated in an endless manner as indicated at a step 2.2 to thereby control the discharge temperature.
Next, the decision made concerning the l33927~
1 temporary stoppage of the control output at the step 2.3 will be elucidated in detail by referring to Fig. 3.
At a step 3.1, it is checked whether the desired discharge temperature Tdo has undergone any change. This step corresponds to the decision or criterion (c) described hereinbefore. In the case of the instant example, it is determined whether a change has occurred in the desired discharge temperature since the preceding arithmetical determination thereof. If the desired discharge temperature has been changed, the value "No" is set at the flag "Stop" to allow the control output signal to be produced because importance is put on the rapid response rather than the stability.
A step 3.3 corresponds to the evaluation with reference to the operational decision (d) mentioned hereinbefore, a step 3.5 corresponds to the evaluation based on the condition (a), a step 3.6 corresponds to the evaluation based on the operational condition (b), and a step 3.9 corresponds to the evaluation based on the operational condition (e).
In this manner, the value "Yes" is set at the flag "Stop" when the temporary stoppage of the control output is required with "No" being otherwise set at the flag "Stop", whereupon the subroutine illustrated in Fig. 3 comes to an end.
Next, arithmetical determination of the control command value mentioned in conjunction with the step 2.5 shown in Fig. 2 will be described in more 1 detail by referring to Figs. 4 and 5.
At a step 4.1 shown in Fig. 4, it is checked whether or not the desired temperature Tdo is substan-tially equal to the actual discharge temperature. This step corresponds to the evaluation based on the condi-tion (f) mentioned hereinbefore. In practice, there can scarcely arise such a situation in which the desired discharge temperature Tdo coincides perfectly with the actual discharge temperature Td. Under the circumstance, it is regarded that the actual discharge temperature Td coincides with the desired discharge temperature Tdo when the difference between these temperatures Tdo and Td is smaller than a previously determined temperature difference ~T. In this case, the control command value is set to zero.
In this connection, the preset difference ~T
may assume a value of 0.3 to 5~C. When this value ~T is small, the control system becomes more sensitive to thereby produce the control command or output signal more frequently. Reversely, when the preset temperature difference ~T is selected at a large value, the control accuracy is correspondingly degraded. In the case of the illustrative embodiment, the value of ~T is set at 1~C.
At the subsequent step 4.3, it is decided whether the negative pressure actuator is to be applied with a negative pressure or to be communicated to the atmosphere. This step corresponds to the decision 133927~
1 based on the condition (i) mentioned hereinbefore. In this conjunction, it is noted in general that difference between the pressure within the negative pressure actuator 2 and the negative pressure source is usually high at the time of application of the negative pressure, which in turn means that even the control output of small magnitude can cause the air blend door 1 to be moved significantly, while in the state in which the negative pressure actuator is communicated to the atmosphere, the pressure difference under consideration is relatively low, requiring thus the control output of large magnitude for accomplishing the same displacement of the air blend door as the case mentioned above.
Accordingly, it is necessary at this step 4.3 to decide whether the negative pressure actuator is to be supplied with the negative pressure or to be communicated to the atmosphere.
Next, at a step 4.4 or step 4.5, the non-linearity of the discharge temperature characteristic of the air conditioning unit is corrected. This step corresponds to the decision based on the criterion (h) mentioned hereinbefore. In general, the discharge temperature characteristic of the air conditioning unit exhibits a non-linear characteristic as a function of the opening of the air blend door 1, as is illustrated in Fig. 5. In order to ensure the system stability, it is important to correct the discharge temperature so that the latter is proportional to the difference I33927~
1 between the desired discharge temperature Tdo and the actual discharge temperature Td. Accordingly, correc-tion of the characteristic with respect to its non-linearity is performed at this step. At the same time, in order to assure the continuity of the control output for both the cases where ¦Tdo - Td¦ < aT is satisfied and dissatisfied, respectively, correction of QT
indicated along the abscissa in connection with the steps 4.4 and 4.5 is performed. This correction corre-sponds to the decision based on the criterion (g)mentioned hereinbefore. Unless correction is performed, then the control output value corresponding to ~T would be produced abruptly or stepwise at the moment the value of ¦Tdo - Td¦ exceeds the temperature difference ~T.
At the next step 4.6, a possible change in the desired discharge temperature Tdo is checked. This step corresponds to the decision based on the criterion (j) mentioned hereinbefore. In the case of the illus-trated embodiment, however, importance is put on the system stability with the control output value being usually set at a smaller value, and when the desired discharge temperature Tdo is varied, the control output value is immediately increased only temporarily. In this manner, compromise and compatibility are established and realized between the stability and the response capability.
As will be appreciated from the foregoing, the present invention provides an inexpensive temperature 1 control apparatus of simplified structure which can nevertheless assure the discharge air temperature control with high stability and response capability without need for the use of a feedback potentiometer or the like to great advantage. In the case of the hitherto-known discharge air temperature control system in which the feedback potentiometer is employed, the amplification factor for the difference signal (¦Tdo - Td¦) can not be set at an excessively high value in view of the stability to be assured for the control system. As a consequence, the temperature control deviation or excursion becomes significant (5 to 10~C) particularly in the vicinity of the m~X; mum cooling position and the m~X; mum warming position, respectively.
According to the illustrated embodiment of the present invention in which the desired discharge temperature Tdo and the actual discharge temperature Td are directly compared with each other and the control is performed so that the difference ~T between the temperatures Tdo and Td approaches to zero, the temperature control deviation or excursion can be suppressed smaller than the given value of the temperature difference ~T, whereby the discharge air temperature can be controlled with high accuracy.
Next, modifications and versions of the illustrated embodiment of the invention will be described.
In conjunction with the system shown in 133927~
1 Fig. 1, the decisions made at the step 3.1 illustrated in Fig. 3 and the step 4.6 in Fig. 4 can be modified as follows.
In the case of the preceding embodiment of the invention, it is decided whether the desired dis-charge temperature Tdo has been changed relative to the value determined by the preceding arithmetic operation because much importance is placed on the response capability. It is however possible that only when the change of the desired discharge temperature Tdo greater than a predetermined value ~T has occurred, decision is made that change in the desired discharge temperature Tdo has taken place. Furthermore, it is also conceiva-ble that only when alteration of the desired intra-car temperature and change-over of the discharge ports by operator and switching of the operation mode of the air conditioning unit take place simultaneously, the decision that the desired discharge temperature Tdo has been changed is rendered valid. In this connection, it should be noted that rapid response is required only in response to the operator's manipulation and switching of the operation mode. For the other conditions, the stability is more important factor. Thus, according to this modification, the stability of the control system can be further enhanced at the expense of slight degradation in the response capability in the regions where high response is of less importance.
Another modification of the preceding 133927~
1 embodiment of the invention is with respect to the decision step 3.9 shown in Fig. 3. More specifically, when some failure occurs in the air conditioning unit or in the control system or when the air blend door has reached the full stroke position, the discharge air temperature does not vary in response to the control output signal. Accordingly, when the insufficient discharge temperature condition continues over a range covering several degrees, it is decided that abnormal temperature regulating condition prevails, and special processings are performed as mentioned below. When the discharge temperature is desired to be increased and when the actual discharge temperature is sufficiently high, it is decided that the air blend door 1 must have been displaced to the maximum warming position. Reverse-ly, when the discharge temperature is to be lowered and when the actual discharge temperature is sufficiently low, it is decided that the air blend door 1 must have been displaced to the maximum cooling position. Accord-ingly, under these conditions, the control outputsignal is interrupted for a predetermined time to inhibit extraneous or unnecessary operations of the negative pressure valves and others. On the other hand, when the conditions mentioned above are not satisfied, it may be decided that the system suffers from some failure.
In that case, a corresponding alarm may be produced to alert the driver of this fact.
According to the modification described above, 13392~4 1 no extraneous operations can take place, whereby use life of the movable parts can be lengthened with operating noise being reduced to advantages. Further-more, due to the possibility of self-diagnosis and alarm generation, the system reliability can be improved to further advantage.
In still another modification of the illus-trated embodiment of the invention, the negative pressure actuator combined with the negative pressure valve for driving the air blend door l may be replaced by an electromagnetic actuator in which an electric motor is made use of or an actuator operative on the basis of the piezo-electricity principle or an actuator in which thermal deformation is made use of or any other actuator capable of moving continuously the air blend door to the similar effects. The modified system in which any one of the abovementioned actuators is used can be controlled in accordance with the procedures illustrated in Figs. 2 to 4 with one exception that the decision step 4.3 is rendered unnecessary to simplify correspond-ingly the control process.
As will now be understood, according to the present invention which teaches that the desired discharge air temperature (Tdo) and the actual discharge temperature (Td) are directly compared with each other, wherein the control is performed so that the difference between these temperatures becomes zero, there can be provided an inexpensive discharge temperature control 133927~
system for a car air conditioner which enjoys various advantages such as simplified structure, high reliability, improve control accuracy and others.
Further due to the feature that the control output command can be temporarily disabled and enabled in dependence on the preestablished conditions, the control system is imparted with both high response capability and high stability.
The present invention relates to an air conditioning apparatus for a motor vehicle which is conventionally referred to as the car air conditioner.
5 More particularly, the invention is concerned with a temperature control system suited preferably for use in the car air conditioner of a reheat-air mix type.
The air conditioning apparatus for a motor vehicle employed in the early stages was of a separate 10 type in which a cooler and a heater were operated independently of each other. In recent years, an air conditioner of a unitary structure referred to as the reheat-air mix (blend) type air conditioner has been developed arld is now used extensively. In this type of 15 air conditioner, temperature control can be performed continuously from cooling to warming mode to maintain --the intra-car temperature at a predetermined value regardless of a wide change in the outside temperature.
Besides, the air conditioner can enjoy excellent tem-~0 perature control in a continuous manner and can arovide moisture removing capability, to further advantage.
A typical one of the reheat-air mix type air conditioners for motor vehicles or cars is known, for example, from Japanese Patent Application Laid-Open No.
25 136509/1983 (~P-A-58-136509) which corresponds to U. S.
Patent No. 4,456,166. In the discharge air *
1 temperature control of this prior art air conditioner, a difference between the actual temperature Td of the discharged air and a desired temperature Tdo to be attained is derived to determine the desired degree of opening ~am of an air mixing or blend door, wherein the control is so performed that a voltage value tapped from a feed back potentiometer may assume a value correspond-ing to the desired opening ~am.
As will be noted, in the prior art air condi-tioner of the type under consideration, a sensor suchas a feedback potentiometer is employed for detecting the opening of the air blend door, the reason for which - may be explained by adoption of such arrangement in which the discharge air temperature control is accom-plished by deriving the difference between the desireddischarge temperature Tdo and the actual discharge temperature Td through direct comparison of these tem-peratures and controlling the opening of the air mixing or blend door so that the temperature difference (Tdo -Td) approaches or converges to zero.
However, notwithstanding of the fact that theopening of the air blend door, a mechanical quantity, can vary within a relatively short time ~within about l second or less), the air temperature at the discharge port can vary only with a large delay in response (about several seconds to several ten seconds) because of influence exerted by the thermal capacity o~ passage walls (walls of ducts and the like) in addition to the 1~39274 1 influence of the delay involved in the response of the discharge temperature sensor itself.
Under the circumstance, when the control system having the delay in response is to be operated with stability and with high-speed response, as occasion requires, it is necessary to detect the opening of the air blend door and control it so that the door can assume constantly the proper state or position. To this end, a feedback potentiometer is employed as in the case of the prior art temperature control system described above.
With the arrangement in which the feedback - potentiometer is employed as the sensor for detecting the degree of opening of the air blend door, an arithmetical determination of the desired opening ~am, processing of the voltage signal produced by the door opening sensor and other processing are required in the course of the control process. Further, since correction must be made on the possible nonuniformity in the positional relationship between the door opening sensor and the air blend door, the control procedure becomes ve ry complicated, which also means that when a microcomputer control is adopted, the program area is correspondingly increased, giving rise to a problem. sesides~ assembling and mounting of a linkage for interlinking the opening sensor and the air blend door with each other, adjust-ment thereof and other steps required for the setup Qf the system are naturally accompanied with high - 13392~4 1 expenditure, which gives rise to another problem.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an inexpensive discharge temperature control system of a simplified structure, high reliability and improved control accuracy by adopting an arrangement in which the discharge temperature ~Td), the final target item to be controlled, is controlled straight-forwardly and which allows the door opening sensor for the air blend door to be omitted while improving the response capability and stability of the controlsystem.
The abovementioned object can be accomplished by adopting at least one of the operational conditions or criteria mentioned below:
(a) For a time of several seconds to several ten of seconds following immediately the opening control of the air blend door, the control output of the control system is interrupted temporarily in view of an inevitable delay involved in generation of the discharge temperature sensor output signal in response to the temperature of the current air stream as discharged.
(b) The output state of the discharge temperature sensor in which the output signal has a large slope as a function of time, i.e. the temperature detected by the discharge temperature sensor changes from time to time, the control output of the control system is 39~4 1 interrupted temporarily, since this state can be regarded as the transient state of the whole system including the mechanical and aerodynamic systems.
(c) Change in the desired discharge temperature (Tdo) brought about by the operator or driver requires the response of the control system without delay.
Accordingly, the control system is released from the temporary stoppage state.
(d) When the actual discharge temperature (Td) varies beyond the desired discharge temperature (Tdo) as the result of operation of the air blend door, the control system is released from the temporary stoppage state so as to make response without delay.
(e) When the effect of the control output for operating the air blend door as reflected on the dis-charge temperature is insufficient (suppose, for çxample, such a situation in which the discharge temper-ature is not changed because the air blend door is not moved at all due to a balanced state estahlished between the spring force applied to the door and the force applied by the actuator even when more or less amount of the atmospheric air is introduced into the actuator with a view to raising the discharge temperature in the state where the maximum negative pressure is applied to attain the maximum cooling), the control system is released from the temporary stoppage state for the purpose of obtaining the satisfactory response.
(f) When a differencc between the desired discharge 13392~4 1 temperature (Tdo) and the actual discharge temperature (Td) is s~laller than a predetermined temperature difference value (~T), no control output is produced, because the above state means that the desired discharge temperature is realized.
(g) When ¦Tdo - Td¦ > ~T, the control quantity (control output or command) is determined as follows:
when Tdo - Td > 0, then Tdo = Td - ~T
when Tdo - Td < 0, then Tdo = Td +(-~T for thereby assuring continuous (smooth) increasing/decreas-ing of the control quantity.
(h) The actual control quantity is corrected on the basis of the value determined as mentioned in the paragraph (g) for thereby compensating for the non-linearity of change in the discharge temperature inresponse to the change in the control quantity for the air conditioning unit.
(i) Difference in the air flow (due to difference in pressure) between the atmospheric pressure and the negative pressure applied to the negative pressure actuator is corrected.
(j) When the desired discharge temperature Tdo is changed, the control output quantity is increased only once for the purpose of enhancing the feeling of ~5 occupants to the response of the control system.
By adopting the operational criteria or conditions (a) to tj) mentioned above, there can be realized a control system having high stability and 133927~
high response speed without using the opening sensor for the air blend door.
In other words, since the control of the means such as the air blend door for regulating the heat exchange capa-bility is performed intermittently in timing with the delayinvolved in the air temperature detection at the discharge port, the air conditioner can be operated stably without resorting to the control by using the door opening sensor.
According to the invention there is provided in an air conditioner installed on a motor vehicle having a temperature control system of a type in which a detected temperature value of air discharged from the air conditioner is controlled convergently to a desired temperature value by regulating a thermal exchange capability of the air condi-tioner through operation of an air blend door, said controlsystem comprising: arithmetic means for arithmetically determining and updating sequentially a deviation of the actual heat exchange capability from a requisite heat exchange capability in accordance with a difference between the detected temperature value and the desired temperature value;
control means operative in response to updated arithmetical deviations to regulate the heat exchange capacity by controlling operation of said blend door on a repeating basis;
decision means for determining whether or not an inhibit signal is connected to said control means and inhibits a control of operation of said blend door by said control means for a period of time immediately after outputting a control signal is produced; means for producing an inhibit signal as a ~ 1339274 result of a decision by said decision means; and means for suppressing production of said inhibit signal according to an operational condition of said air conditioner.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a view showing schematically an arrangement of a typical air conditioner for a motor vehicle to which an automatic temperature control system according to an embodiment of the present invention is applied;
Fig. 2 is a view for illustrating operation of the system according to an embodiment of the invention;
Figs. 3 and 4 are views for illustrating some steps shown in Fig. 2 in more detail; and Fig. 5 is a view for illustrating the discharge temperature control characteristic of a typical air conditioning unit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, the present invention will be described in detail by referring to the annexed drawings which 1~39274 1 show a temperature control system for a car air condi-tioner according to an exemplary embodiment of the invention.
Fig. 1 shows schematically a general arrange-ment of a car air conditioner provided with a temperaturecontrol system according to an embodiment of the inven-tion. In the figure, an air conditioning unit 10, an evaporator 11 and a heater core 12 are, respectively, of conventional structures. As the elements which partake directly in the discharge air temperature control taught by the invention, there can be mentioned an air blend (mixing) door 1, a negative pressure (vacuum) ~ctuator 2, an on/off valve 3, a three-way valve 4, a discharged air temperature sensor 5 and a controller 6.
An intra-car (interior) temperature setting unit 7, an atmospheric (exterior) temperature sensor 8, an intra-car temperature sensor 9 and others are also connected to the controller 6 although they bear no direct relevance to the control proposed by the present inven-tion.
Next, operation in general of the illustratedsystem will be described.
The controller 6 includes a microcomputer and fetches a signal Ts tapped from the intra-car temperature setting unit 7, a temperature signal Ta produced by the atmospheric temperature sensor 8, a temperature signal Tr produced by the intra-car temperature sensor 9 and other parameters, if any, to thereby determine 133927~
l arithmetically a desired (target) discharge temperature Tdo and control various members (not shown) participat-ing in the control of the air conditioner.- Among others, the control of the air blend door 1 is performed in such a manner in which the negative pressure actuator 2 is operated under the control of the controller 6 through the on/off valve 3 and the three-way valve 4 which in turn are controlled in response to signals Vs and V3 produced by the controller 6, whereby the operating position of the air blend door l is correspondingly established.
More specifically, the three-way valve 4 is first connected to a negative pressure source in response to the signal V3. Subsequently, the on/off valve 3 is opened for a predetermined time in response to the signals Vs. Thus, a negative pressure is introduced into the negative pressure actuator 2, whereby the air blend (mixing) door 1 is displaced toward the cooling position by an angle of the magnitude corresponding to the operating time duration of the on/off valve 3, resulting in that the actual discharge temperature is lowered. Reversely, when the three-way valve 4 is so changed over as to communicate with the atmosphere with the on/off valve 3 being subsequently operated to thereby allow the atmospheric air to be introduced into the negative pressure actuator 2, the air blend door 1 is displaced toward the warming side, as the result of which the output temperature rises. The i~ 1339274 1 actual discharge temperature Td of the air discharged through an outlet port OUT of the air conditioner is detected by the discharged air temperature sensor 5 whose output signal is inputted to the controller 6 to be utilized in the arithmetic determination of the desired discharge temperature Tdo. The signals V and V3 resulting from the above calculation are outputted from the controller 6.
Next, arithmetic operation and control procedure performed in this illustrated system will be elucidated in conjunction with Fig. 2 which illustrates the control procedure in a so-called program analysis diagram (PAD in abbreviation).
Referring to Fig. 2, the optimum desired discharge temperature Tdo is arithmetically determined at a step 2.1 on the basis of the aforementioned intra-car set temperature Ts, the atmospheric temperature Ta, the actual intra-car temperature Tr and other parameters.
At the subsequent step 2.2, the actual discharge tem-perature is determined on the basis of the signal Td available from the discharge temperature sensor 5. So far as the steps 2.1 and 2.2 described above are concerned, the control procedure is the same as that of the conventional air conditioner controlling system.
At a step 2.3, the timing at which the control signal is to be outputted is determined. In actuality, this step is a looped-back subroutine in which the operational conditions (a) to (e) described hereinbefore 1 are evaluated, and a value "Yes" is set at the flag "Stop" at the time when the control output is to be stopped temporarily.
At the following step 2.4, the content of the flag "Stop" is checked. When the value "Yes" is set at this flag, the step 2.1 is regained without executing any processing. On the other hand, when the content of the flag "Stop" is found to be "No", the control is transferred to a subsequent step 2.5 for releasing the control system from the temporary stoppage state.
At a step 2.5, a control output or command value indicative of the magnitude of displacement for which the air blend door 1 is to be moved is arithmeti-cally determined on the basis of the desired discharge temperature Tdo and the actual discharge temperature Td in accordance with the aforementioned operational conditions or criteria (f) to (j).
When the control command or output value is zero, no processing is executed at the next step 2.6 because no control output quantity is required to be produced. Only when the control command value is not zero, a control output signal corresponding to the control command value is produced for controlling the displacement of the air blend or mixing door 1.
The sequence of the individual steps described above is repeated in an endless manner as indicated at a step 2.2 to thereby control the discharge temperature.
Next, the decision made concerning the l33927~
1 temporary stoppage of the control output at the step 2.3 will be elucidated in detail by referring to Fig. 3.
At a step 3.1, it is checked whether the desired discharge temperature Tdo has undergone any change. This step corresponds to the decision or criterion (c) described hereinbefore. In the case of the instant example, it is determined whether a change has occurred in the desired discharge temperature since the preceding arithmetical determination thereof. If the desired discharge temperature has been changed, the value "No" is set at the flag "Stop" to allow the control output signal to be produced because importance is put on the rapid response rather than the stability.
A step 3.3 corresponds to the evaluation with reference to the operational decision (d) mentioned hereinbefore, a step 3.5 corresponds to the evaluation based on the condition (a), a step 3.6 corresponds to the evaluation based on the operational condition (b), and a step 3.9 corresponds to the evaluation based on the operational condition (e).
In this manner, the value "Yes" is set at the flag "Stop" when the temporary stoppage of the control output is required with "No" being otherwise set at the flag "Stop", whereupon the subroutine illustrated in Fig. 3 comes to an end.
Next, arithmetical determination of the control command value mentioned in conjunction with the step 2.5 shown in Fig. 2 will be described in more 1 detail by referring to Figs. 4 and 5.
At a step 4.1 shown in Fig. 4, it is checked whether or not the desired temperature Tdo is substan-tially equal to the actual discharge temperature. This step corresponds to the evaluation based on the condi-tion (f) mentioned hereinbefore. In practice, there can scarcely arise such a situation in which the desired discharge temperature Tdo coincides perfectly with the actual discharge temperature Td. Under the circumstance, it is regarded that the actual discharge temperature Td coincides with the desired discharge temperature Tdo when the difference between these temperatures Tdo and Td is smaller than a previously determined temperature difference ~T. In this case, the control command value is set to zero.
In this connection, the preset difference ~T
may assume a value of 0.3 to 5~C. When this value ~T is small, the control system becomes more sensitive to thereby produce the control command or output signal more frequently. Reversely, when the preset temperature difference ~T is selected at a large value, the control accuracy is correspondingly degraded. In the case of the illustrative embodiment, the value of ~T is set at 1~C.
At the subsequent step 4.3, it is decided whether the negative pressure actuator is to be applied with a negative pressure or to be communicated to the atmosphere. This step corresponds to the decision 133927~
1 based on the condition (i) mentioned hereinbefore. In this conjunction, it is noted in general that difference between the pressure within the negative pressure actuator 2 and the negative pressure source is usually high at the time of application of the negative pressure, which in turn means that even the control output of small magnitude can cause the air blend door 1 to be moved significantly, while in the state in which the negative pressure actuator is communicated to the atmosphere, the pressure difference under consideration is relatively low, requiring thus the control output of large magnitude for accomplishing the same displacement of the air blend door as the case mentioned above.
Accordingly, it is necessary at this step 4.3 to decide whether the negative pressure actuator is to be supplied with the negative pressure or to be communicated to the atmosphere.
Next, at a step 4.4 or step 4.5, the non-linearity of the discharge temperature characteristic of the air conditioning unit is corrected. This step corresponds to the decision based on the criterion (h) mentioned hereinbefore. In general, the discharge temperature characteristic of the air conditioning unit exhibits a non-linear characteristic as a function of the opening of the air blend door 1, as is illustrated in Fig. 5. In order to ensure the system stability, it is important to correct the discharge temperature so that the latter is proportional to the difference I33927~
1 between the desired discharge temperature Tdo and the actual discharge temperature Td. Accordingly, correc-tion of the characteristic with respect to its non-linearity is performed at this step. At the same time, in order to assure the continuity of the control output for both the cases where ¦Tdo - Td¦ < aT is satisfied and dissatisfied, respectively, correction of QT
indicated along the abscissa in connection with the steps 4.4 and 4.5 is performed. This correction corre-sponds to the decision based on the criterion (g)mentioned hereinbefore. Unless correction is performed, then the control output value corresponding to ~T would be produced abruptly or stepwise at the moment the value of ¦Tdo - Td¦ exceeds the temperature difference ~T.
At the next step 4.6, a possible change in the desired discharge temperature Tdo is checked. This step corresponds to the decision based on the criterion (j) mentioned hereinbefore. In the case of the illus-trated embodiment, however, importance is put on the system stability with the control output value being usually set at a smaller value, and when the desired discharge temperature Tdo is varied, the control output value is immediately increased only temporarily. In this manner, compromise and compatibility are established and realized between the stability and the response capability.
As will be appreciated from the foregoing, the present invention provides an inexpensive temperature 1 control apparatus of simplified structure which can nevertheless assure the discharge air temperature control with high stability and response capability without need for the use of a feedback potentiometer or the like to great advantage. In the case of the hitherto-known discharge air temperature control system in which the feedback potentiometer is employed, the amplification factor for the difference signal (¦Tdo - Td¦) can not be set at an excessively high value in view of the stability to be assured for the control system. As a consequence, the temperature control deviation or excursion becomes significant (5 to 10~C) particularly in the vicinity of the m~X; mum cooling position and the m~X; mum warming position, respectively.
According to the illustrated embodiment of the present invention in which the desired discharge temperature Tdo and the actual discharge temperature Td are directly compared with each other and the control is performed so that the difference ~T between the temperatures Tdo and Td approaches to zero, the temperature control deviation or excursion can be suppressed smaller than the given value of the temperature difference ~T, whereby the discharge air temperature can be controlled with high accuracy.
Next, modifications and versions of the illustrated embodiment of the invention will be described.
In conjunction with the system shown in 133927~
1 Fig. 1, the decisions made at the step 3.1 illustrated in Fig. 3 and the step 4.6 in Fig. 4 can be modified as follows.
In the case of the preceding embodiment of the invention, it is decided whether the desired dis-charge temperature Tdo has been changed relative to the value determined by the preceding arithmetic operation because much importance is placed on the response capability. It is however possible that only when the change of the desired discharge temperature Tdo greater than a predetermined value ~T has occurred, decision is made that change in the desired discharge temperature Tdo has taken place. Furthermore, it is also conceiva-ble that only when alteration of the desired intra-car temperature and change-over of the discharge ports by operator and switching of the operation mode of the air conditioning unit take place simultaneously, the decision that the desired discharge temperature Tdo has been changed is rendered valid. In this connection, it should be noted that rapid response is required only in response to the operator's manipulation and switching of the operation mode. For the other conditions, the stability is more important factor. Thus, according to this modification, the stability of the control system can be further enhanced at the expense of slight degradation in the response capability in the regions where high response is of less importance.
Another modification of the preceding 133927~
1 embodiment of the invention is with respect to the decision step 3.9 shown in Fig. 3. More specifically, when some failure occurs in the air conditioning unit or in the control system or when the air blend door has reached the full stroke position, the discharge air temperature does not vary in response to the control output signal. Accordingly, when the insufficient discharge temperature condition continues over a range covering several degrees, it is decided that abnormal temperature regulating condition prevails, and special processings are performed as mentioned below. When the discharge temperature is desired to be increased and when the actual discharge temperature is sufficiently high, it is decided that the air blend door 1 must have been displaced to the maximum warming position. Reverse-ly, when the discharge temperature is to be lowered and when the actual discharge temperature is sufficiently low, it is decided that the air blend door 1 must have been displaced to the maximum cooling position. Accord-ingly, under these conditions, the control outputsignal is interrupted for a predetermined time to inhibit extraneous or unnecessary operations of the negative pressure valves and others. On the other hand, when the conditions mentioned above are not satisfied, it may be decided that the system suffers from some failure.
In that case, a corresponding alarm may be produced to alert the driver of this fact.
According to the modification described above, 13392~4 1 no extraneous operations can take place, whereby use life of the movable parts can be lengthened with operating noise being reduced to advantages. Further-more, due to the possibility of self-diagnosis and alarm generation, the system reliability can be improved to further advantage.
In still another modification of the illus-trated embodiment of the invention, the negative pressure actuator combined with the negative pressure valve for driving the air blend door l may be replaced by an electromagnetic actuator in which an electric motor is made use of or an actuator operative on the basis of the piezo-electricity principle or an actuator in which thermal deformation is made use of or any other actuator capable of moving continuously the air blend door to the similar effects. The modified system in which any one of the abovementioned actuators is used can be controlled in accordance with the procedures illustrated in Figs. 2 to 4 with one exception that the decision step 4.3 is rendered unnecessary to simplify correspond-ingly the control process.
As will now be understood, according to the present invention which teaches that the desired discharge air temperature (Tdo) and the actual discharge temperature (Td) are directly compared with each other, wherein the control is performed so that the difference between these temperatures becomes zero, there can be provided an inexpensive discharge temperature control 133927~
system for a car air conditioner which enjoys various advantages such as simplified structure, high reliability, improve control accuracy and others.
Further due to the feature that the control output command can be temporarily disabled and enabled in dependence on the preestablished conditions, the control system is imparted with both high response capability and high stability.
Claims (8)
1. In an air conditioner installed on a motor vehicle having a temperature control system of a type in which a detected temperature value of air discharged from the air conditioner is controlled convergently to a desired temperature value by regulating a thermal exchange capability of the air conditioner through operation of an air blend door, said control system comprising:
arithmetic means for arithmetically determining and updating sequentially a deviation of the actual heat exchange capability from a requisite heat exchange capability in accordance with a difference between the detected temperature value and the desired temperature value;
control means operative in response to updated arithmetical deviations to regulate the heat exchange capacity by controlling operation of said blend door on a repeating basis;
decision means for determining whether or not an inhibit signal is connected to said control means and inhibits a control of operation of said blend door by said control means for a period of time immediately after outputting a control signal is produced;
means for producing an inhibit signal as a result of a decision by said decision means; and means for suppressing production of said inhibit signal according to an operational condition of said air conditioner.
arithmetic means for arithmetically determining and updating sequentially a deviation of the actual heat exchange capability from a requisite heat exchange capability in accordance with a difference between the detected temperature value and the desired temperature value;
control means operative in response to updated arithmetical deviations to regulate the heat exchange capacity by controlling operation of said blend door on a repeating basis;
decision means for determining whether or not an inhibit signal is connected to said control means and inhibits a control of operation of said blend door by said control means for a period of time immediately after outputting a control signal is produced;
means for producing an inhibit signal as a result of a decision by said decision means; and means for suppressing production of said inhibit signal according to an operational condition of said air conditioner.
2. A temperature control system according to claim 1, wherein the air conditioner has an air blend door for regulating air discharged from the air conditioner, and said control means has an input signal from a sensor for detecting discharge air temperature, there being no input signal to said control means which relates to a position of said air blend door.
3. A temperature control system according to claim 2, wherein said decision means determines whether to produce an inhibit signal at a condition of a rate of change in the temperature of the discharged air which is larger than a predetermined rate of change.
4. A temperature control system according to claim 3, wherein suppression of an inhibit signal occurs when the desired temperature value is adjusted by an operator.
5. A temperature control system according to claim 4, wherein suppression of an inhibit signal occurs when the detected temperature value goes beyond the desired temperature value.
6. A temperature control system according to claim 5, wherein suppression of the inhibit signal occurs when a change in the detected temperature value occurring in response to alteration of the heat exchange capability caused by a preceding output of the control means fails to attain a predetermined rate of change.
7. A temperature control system according to claim 6, wherein the suppression of an inhibit signal occurs temporarily only once in response to a change of the desired temperature value by the operator.
8. A temperature control system according to claim 1, wherein said means for suppressing suppresses production of an inhibit signal before termination of said period of time when a target temperature of said air conditioner is changed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP210621/86 | 1986-09-09 | ||
| JP61210621A JP2500805B2 (en) | 1986-09-09 | 1986-09-09 | Automotive air conditioner temperature controller |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1339274C true CA1339274C (en) | 1997-08-12 |
Family
ID=16592358
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000546284A Expired - Fee Related CA1339274C (en) | 1986-09-09 | 1987-09-08 | Temperature controller for car air conditioner |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2500805B2 (en) |
| KR (1) | KR880003766A (en) |
| CA (1) | CA1339274C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0773971B2 (en) * | 1987-04-22 | 1995-08-09 | 株式会社日立製作所 | Blower temperature control device for automobile air conditioners |
| JP4934555B2 (en) * | 2007-09-25 | 2012-05-16 | ミキスタ工業株式会社 | Casting equipment |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55164519A (en) * | 1979-06-12 | 1980-12-22 | Nippon Denso Co Ltd | Controlling device for air-conditioner |
| JPS6164518A (en) * | 1984-09-05 | 1986-04-02 | Mazda Motor Corp | Air conditioner of vehicle |
-
1986
- 1986-09-09 JP JP61210621A patent/JP2500805B2/en not_active Expired - Lifetime
-
1987
- 1987-09-04 KR KR870009794A patent/KR880003766A/en not_active IP Right Cessation
- 1987-09-08 CA CA000546284A patent/CA1339274C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2500805B2 (en) | 1996-05-29 |
| KR880003766A (en) | 1988-05-30 |
| JPS6368415A (en) | 1988-03-28 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |