Vehicular air conditioner

When there arises a need to change an air conditioner capability, a vehicular air conditioner capable of easily meeting this need is achieved. Also, even if some of a plurality of air conditioner units break down, a vehicular air conditioner capable of properly air conditioning a vehicular space using other air conditioner units, is achieved.This vehicular air conditioner includes a controller 20 for calculating a total heat supply amount, based on a target temperature and an actual room temperature; at least one heater 5 and/or at least one cooler 6; a controller 20 that sets generated heat amounts of the heater 5 and/or the cooler 6 of each of the air conditioner units 30, based on a calculated total heat supply amount and the number of used air conditioner units 30; and a drive controller that controls operations of the heater 5 and/or the cooler 6, based on the generated heat amounts that have been set.

TECHNICAL FIELD

The present invention relates to an air conditioner for adjusting an interior temperature, and specifically, to a vehicular air conditioner suitable for applications in an electric car or bus.

BACKGROUND ART

Conventionally, as an example of vehicular air conditioner, there is an air conditioner of a type in which plurality of air conditioner units are used to air-condition a plurality of zones, into which a vehicular space is divided (refer to Patent Document 1 for example).

DISCLOSURE OF INVENTION

Problems to be Solved by the Invention

However, in the conventional vehicular air conditioner as described above, when there has arisen a need to change the air conditioning capability because of a change of the district where the vehicle runs, it has been necessary that almost all air conditioner units provided in the air conditioner are replaced with ones different in the capability.

Also, in the case when one of the air conditioner units has failed, even if other air conditioner units have margins of capabilities, there has occurred a problem in that the air conditioning for the zone corresponding to the failing unit becomes unsatisfactory.

The present invention has been made to solve the above-described problems. A first object of the present invention is to easily achieve a vehicular air conditioner capable of being accommodated to a situation in which there arises a need to change the air conditioning capability. Furthermore, a second object of the present invention is, even if some of the plurality of air conditioner units fails, to achieve a vehicular air conditioner enabling proper air conditioning of the vehicular space using other air conditioner units.

Means for Solving the Problems

A vehicular air conditioner according to the present invention comprises a plurality of air conditioner units, each including heat supply amount setting means for setting a heat supply amount; at least one heat generator and/or at least a cooled heat generator; and drive control means for controlling operations of the heat generator and/or the cooled heat generator, based on the heat supply amount set by the heat supply amount setting means, wherein a predetermined heat amount is supplied to the interior of a vehicle by operating the plurality of air conditioner units in combination.

Advantages

The vehicular air conditioner according to the present invention is configured so that a predetermined heat amount is supplied into the interior of a vehicle by operating a plurality of air conditioner units in combination. Therefore, when there arises a need to change the air conditioning capability, the present vehicular air conditioning produces an effect of being easily capable of meeting this need only by increasing or decreasing the number of air conditioner units. Also, when some of the plurality of air conditioner units fail, the present vehicular air conditioner produces an effect of performing an proper air conditioning of a vehicular space by using other air conditioner units.

REFERENCE NUMERALS

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment

FIG. 1is a schematic view of an application of a vehicular air conditioner according to a first embodiment of the present invention. InFIG. 1, a vehicle1(irrespective of whether an electric car or a bus) into which this vehicular air conditioner is incorporated, is assumed to comprise an interior space2for a person(s) and/or cargo(s), and an underfloor space3to accommodate various devices. Two air conditioner units30constituting the vehicular air conditioner are installed in underfloor space3. Each of the air conditioner units30includes a heater5serving as a heat generator, a cooler6serving as a cooled heat generator, an indoor fan7, and an outdoor fan8. The cooler6includes a refrigeration cycle constituted of a compressor60, an evaporator61, a condenser62, and an expansion valve63, as shown inFIG. 2. Also, a room temperature sensor50is provided in a portion where indoor air enters the evaporator61.

In a narrow sense, the vehicular air conditioner according to the present invention indicates only a plurality of air conditioner units30used in combination, but in a broad sense, it includes also the room temperature sensor50and ducts4,4A, and4B accompanying the air conditioner units30, besides the air conditioner units30.

In the above-described vehicle1, air in the interior space2is taken in from an interior air intake port11, and supplied to the two air conditioner units30. Inside each of the air conditioner units30, the air passes through the evaporator61, and after having been driven by the indoor fan7, it is fed from the air conditioner units30to the respective exclusive ducts4A and4B. Thereafter, the air having exited from the respective exclusive ducts4A and4B is mixed in the common duct4, and supplied to the interior space2. On the other hand, outside air driven by the indoor fan7passes through the condenser62.

FIG. 3is a block diagram showing the air conditioner units constituting the vehicular air conditioner and its peripheral devices according to the first embodiment of the present invention. This vehicular air conditioner comprises the two air conditioner units30, a console panel40serving as target temperature setting means in air conditioning, and a room temperature sensor50serving as room temperature detecting means.

As descried above, the air conditioner unit30includes heaters5and a cooler6. In the case of this air conditioner unit30, there are provided three heaters5each having a generated heat amount of 2 kW, with the total generated heat amount being 6 kW. The three heaters5are subjected to control of their energization state by their respective three relays9, and their operations (heat generation) are controlled. On the other hand, the cooler6consists of a single cooler alone, and the cooled heat amount of the cooler6is controlled by varying the operation frequency of the compressor60constituting the cooler6. For this air conditioner unit30, the control of operation frequency of compressor60is performed by using an inverter10.

Furthermore, the air conditioner unit30has a controller20for controlling operations of the relays9and inverter10.

Here, the relationship between the operation frequency of the compressor60and the cooled heat amount of the cooler6is shown in Table 1 for example. In Table 1, minus values indicate cooled heat amounts.

The flow of a control signal (or control information) in the vehicular air conditioner inFIG. 3is as follows. Temperature information from the console panel40and room temperature sensor50is captured into the controller20of each of the air conditioner units30. Based on the captured temperature information, an operation control signal with respect to each of the heaters or the cooler6are produced in the controller20. Then, these operation control signals are sent to relays9and the inverter10. Based on the operation control signals, the relays9control the energization of the heaters5, and the inverter10controls the operation frequency of the compressor60for the cooler.

FIG. 4is a block diagram showing the construction of the controller20inFIG. 3. The controller20comprises a PI control portion21serving as a total heat supply amount calculation portion, a heater generated heat amount setting portion22serving as a generated heat amount setting portion, a cooled heat amount setting portion24serving as a generated cold heat amount setting portion, a heater duty factor control portion23constituting heater drive control means together with the relays9, a compressor frequency control portion25constituting cooler drive control means together with the inverter10, and an operation go/no-go information holding portion26concerning the heaters5and cooler6.

Here, the PI control portion21, heater generated heat amount setting portion22, and cooled heat amount setting portion24are collectively referred to as heat supply amount setting means. Also, the heater generated heat amount setting portion22and cooled heat amount setting portion24are collectively referred to as a generated heat amount/cooled heat amount setting portion. Furthermore, the heater duty factor control portion23and compressor frequency control portion25are collectively referred to as drive control means.

This controller20comprises a microcomputer in which functions of the above-described portions are programmed.

The PI control portion21is configured to perform a feedback calculation of a total heat supply amount (synonymous with a total generated heat amount) of the plurality of air conditioner units30, using proportion-integration control. Specifically, the PI control portion21calculates a heat supply amount command value Q as a total heat supply amount, based on target temperature information from the console panel40and room temperature information from the room temperature sensor50. Here, the heat supply amount command value Q can be calculated also by using proportion-integration-differentiation control. In that case, the total heat supply amount calculation portion constitutes a PID control portion.

Based on the heat supply amount command value Q from the PI control portion21, the number of air conditioner units30capable of operating heaters and the number of operable heaters5obtained from the operation go/no-go information holding portion26, the heater generated heat amount setting portion22sets a heat amount to be generated in the heaters5of the pertinent air conditioner units30.

The heater duty factor control portion23performs control (duty factor control) with respect to the relays9energizing the heaters5, based on the heat amount set by the heater generated heat amount setting portion22.

Based on the heat supply amount command value Q from the PI control portion21, the number of air conditioner units30capable of cooling operation and the number of operable coolers6obtained from the operation go/no-go information holding portion26, the cooled heat amount setting portion24sets a heat amount to be generated in the coolers6of the pertinent air conditioner units30.

The compressor frequency control portion25sets an operation frequency of the compressor60constituting the cooler6, based on the heat amount set by the cooled heat amount setting portion24, and transmits the set value to the inverter10.

The operation go/no-go information holding portion26detects respective failures of the heaters5and coolers6, and stores the respective numbers of operable heaters5and coolers6. The information stored in the operation go/no-go information holding portion26is mutually communicated and shared between the air conditioner units.

Next, operations of the above-described vehicular air conditioner will be described. A target temperature of the interior space2is set by the console panel40, and the current room temperature is detected by the room temperature sensor50. These pieces of temperature information are captured by the controller20of each of the plurality of air conditioner units30.

In the PI control portion21of the controller20, the heat supply amount command value Q is calculated from the sum of the difference between a target temperature and room temperature, multiplied by a proportion gain, and a time integration of the difference, multiplied by an integration gain. This is proportion integration control for feeding back the room temperature whereby the room temperature is controlled to be a target temperature.

The operation go/no-go information holding portion26detects whether the heaters5and cooler6of the pertinent air conditioner unit30are operable, and exchanges information on the number of operable heaters5and cooler6with other air conditioner units30. Here, if blowing by the indoor fan7is impossible, the heaters5and cooler6are both disapproved of operating.

The heat supply amount command value Q produced in the PI control portion21is sent to the heater generated heat amount setting portion22and cooled heat amount setting portion24.

Based on the heat supply amount command value Q, the heater generated heat amount setting portion22and cooled heat amount setting portion24set heat amounts to be generated (synonymous with heat supply amounts) in the heaters5and cooler6of the pertinent air conditioner unit30. These settings are performed in conformance to setting patterns stored in advance in the above-described setting portions. The setting patterns are collected as a heat amount setting correspondence table, based on cooled heat amounts of the cooler6and predetermined variables. An example of the heat amount setting correspondence table is shown in Table 2.

When the cooler6mounted in each of the air conditioner units30is in good order, variables N in Table 2 indicate the number of air conditioner units30that are provided. In this vehicular air conditioner, therefore, when the cooler6is in good order, N=2 is given. If the number of the mounted air conditioner units is changed, it suffices only to change a value to be given to the variable N. Thus, the change in the number of air conditioner units can be easily coped with, without the need for a change in the control algorithm or the like.

On the other hand, suppose the case where the cooler6is out of order. When there is an air conditioner unit30of which the cooler6is out of order, the number of air conditioner units30capable of operating the coolers6is procured from the operation go/no-go information holding portion26, and this number is used as the variable N.FIG. 5is a flowchart showing a setting method for such a variable N.

If there are air conditioner units having no cooler, the number of those air conditioner units is not included in the variable N.

In the heat amount correspondence table (Table 2), the generated heat amount of the cooler6is stepwise varied in accordance with the heat supply amount command value Q. The purpose of this is to avoid the occurrence of a breakage or failure due to a resonance of a piping system, by operating the compressor60constituting the cooler only at operation frequencies that ensure safety. The operation frequencies of the compressor60are not necessarily limited to the values shown in Table 1.

In this manner, since the setting of a heat amount is performed by using the heat amount correspondence table, even when attempting to change a characteristic of the cooler6, it suffices only to correct the heat amount correspondence table. Thus, the change in characteristic of the cooler6can be easily coped with, without the need for a change in the control algorithm.

The generated heat amount of the heaters5is set so as to supply the heat amount in conformity with the heat supply amount command value Q by the entire vehicular air conditioner. The generated heat amount of heaters5is stepwise varied by switching on/off the heaters5by the relays9, but macroscopically, the heat supply amount is controlled to continuously vary under duty factor control. specifically, the generated heat amount per hour is continuously varied by varying the ratio of the energization time to the energization cycle.

Concurrently switching on/off a plurality of heaters5greatly changes power consumption in an instantaneous manner. The capacity of a power generator provided in vehicle devices has a limitation, and a great instantaneous change in power consumption has an adverse effect on the maintenance of a power source voltage. In the worst case, there are apprehensions of the occurrence of a stop of power generation system, or detrimental effects of fluctuations of the power source voltage on other vehicle devices. Accordingly, the timing of heater energization by the relays is varied by the number of air conditioner units30to be operated and the number of heaters5to be used, in addition to the setting of the generated heat amount of the heaters5, under the condition in which a plurality of heaters5are not concurrently switched on/off. In this example, two air conditioner units30each use three of the heaters5. Here, as shown inFIG. 7(a), the on-timings of three heaters5of each single air conditioner unit30is designed to deviate from each other by ⅓ cycle, and the heater on-timings of two-air conditioner units30are designed to deviate from each other by ⅙ cycle. Taken all together, therefore, six heaters in total have on-timings that deviate from each other by ⅙ cycle, thus preventing the six heaters from being concurrently switched on. Furthermore, it is preferable that the duty factors of all heaters be set so as to be equal to each other, to thereby prevent a plurality of heaters from being concurrently switched off.

Next, regarding a single air conditioner unit30, suppose that one of its three heaters5fails and the umber of usable heaters becomes two. In this case, when attempting to equalize the generated heat amounts of two air conditioner units30, the duty factor per heater is different between an air conditioner unit30that can use two heaters and another air conditioner unit30that can use three heaters. At this time, even if a setting is performed so that their on-timings do not overlap between the air conditioner units, their off-timings may overlap. To avoid this, as shown inFIG. 7(b), even in the air conditioner unit having three usable heaters, only two heaters are used. Here, the on-timings of the two heaters of each air conditioner unit are designed to deviate from each other by ½ cycle, and the on-timings of two air conditioner units are designed to deviate from each other by ¼ cycle. Furthermore, it is preferable that duty factors of all heaters be set so as to be equal to each other, thereby to prevent on-timings and off-timings from overlapping among the heaters.

Based on a conception similar to the foregoing, when the number of used air conditioner units changes, or when the number of heaters in the air conditioner unit changes, the timing deviation amount between heaters is determined as follows.

When Nu units of air conditioner units each use ne pieces of heaters, the phase of the n-th heater of the N-th air conditioner unit is assumed to be given by the following expression.
((N−1)÷(Nu×ne)+(n−1)÷ne)×Ts
Here, Ts denotes an energization cycle.

Thereby, the timings of the heaters deviate from each other by [1÷(Nu×ne)] cycles. This allows a plurality of heaters to be prevented from being concurrently switched on/off.

As described above, in order to air-condition the vehicular space, the vehicular air conditioner operates a plurality of air conditioner units30in combination, each air conditioner unit30including the PI control portion21, heater generated heat amount setting portion22, cooled heat amount setting portion24, and operation go/no-go information holding portion (these are referred to as the heat supply amount setting means); heater duty factor control portion23and relays9(these are referred to as the heat generation control means); compressor frequency control portion25and inverter10(these are referred to as the cold heat generation control means); operation go/no-go information holding portion26; heaters5; and cooler6. The present vehicular air conditioner has the following effects.When a need to change the air conditioning capability arises, this need can be easily met by increasing or decreasing the number of air conditioner units.The generated heat amounts of the heaters5and cooler6of each of the air conditioner unit are designed to be set based on the number of air conditioner units, and therefore, even if the number of air conditioner units provided is changed, it is possible to easily cope with this change.Since the generated heat amounts of the heaters5and cooler6are designed to be set based on the operation go/no-go information on the heaters5and cooler6, stable control is achievable even if a failure occurs.The patterns of heat amounts to be generated by the heater5and cooler6are tabled and held. Control is performed based on these patterns, and therefore, when attempting to change the characteristic of the cooler6, it suffices only to correct the table. Thus, the change in the cooler characteristic can be easily coped with, without the need for a change in the control algorithm.Since the total heat supply amount is determined by a feedback calculation by the target temperature information set by the console panel40and the room temperature information detected by the room temperature sensor50, a user can obtain a target temperature adjustment only by setting a target temperature, without being conscious of the heat supply amount of the air conditioner. Specifically, it is possible to perform a temperature adjustment with an error on the level of ±1° C. by using the PI control or PID control.Since the heat supply amount is varied by stepwise varying the operation frequency of the compressor60only at frequencies that ensures safety, it is possible to avoid the occurrence of a breakage or failure due to a resonance of a piping system. Here, the variation in the operation frequency can be easily achieved by using the inverter10.Since the heater5is subjected to duty factor control, it is possible to utilize a simple device such as a relay9as an energization control device for the heater5, and also to obtain macroscopically continuous change in the generated heat amount, thereby allowing a target heat supply amount to be quickly generated from the air conditioner unit30.Since the deviation amounts of the energization timing of heaters5between air conditioner units30are determined by the number of air conditioner units30and the number of heaters5of each of the air conditioner units30, it is possible to prevent a plurality of heaters5from concurrently starting energization, thereby allowing the avoidance of a detrimental effect on the power source device.Since the numbers of operable heaters in each of the air conditioner units30are compared with one another, and to the number of operable heaters in an air conditioner unit30having fewest operable heaters out of all of the air conditioner units, the number of operable heaters of the other air conditioner units is conformed, it is possible to prevent a plurality of heaters5from concurrently starting energization even if some of the heaters5fail, thereby allowing the avoidance of a detrimental effect on the power source device.When Nu units of air conditioner units each use ne pieces of heaters, the phase of the n-th heater of the N-th air conditioner unit is assumed to be given by the following expression.
((N−1)÷(Nu×ne)+(n−1)÷ne)×Ts,
where Ts denotes an energization cycle.

Thereby, a plurality of heaters5are prevented from concurrently starting energization. This allows the avoidance of a detrimental effect on the power source device.The duty factors of all heaters used is designed to be equal to each other, so that, when a plurality of heaters5are prevented from concurrently starting energization, it is also prevented that the plurality of heaters5concurrently finish energization, as well. This allows the avoidance of a detrimental effect on the power source device.

In the first embodiment, the room temperature sensor50is disposed outside the air conditioner unit30. However, the arrangement may be such that the room temperature sensor50is disposed inside some air conditioner unit30, e.g., in an air intake portion of the evaporator61, and that a plurality of air conditioner units30use the identical value of room temperature through mutual communications between the plurality of air conditioner units30.

Second Embodiment

In the first embodiment, heat amounts generated in a plurality of air conditioner units are all arranged to be equal to each other, but in a second embodiment, examples in which generated the heat amounts generated in all of the plurality of air conditioner units are not necessarily equal to each other, are shown. Here, the disposition relationship between a vehicle and air conditioner units is the same as that shown inFIG. 1, and the construction of a cooler is the same as that shown inFIG. 2.

FIG. 6is a block diagram showing a vehicular air conditioner and flows of control signals according to the second embodiment of the present invention. This vehicular air conditioner includes two air conditioner units30A each having an imparted order, console panel40, and room temperature sensor50. Each of the air conditioner unit30A has one heater5and one relay for controlling the heater. The generated heat amount of the heater5is assumed to be 2.5 kW. Also, there is provided one cooler6, and its generated heat amount is controlled under operation frequency control of compressor60by the inverter10. Here, the relationship between the frequency of the cooler60and the generated heat amount of the cooler6is assumed to be the same as that shown in Table 1 in the first embodiment. There is also provided the same controller20as that shown in the first embodiment.

Based on the heat supply amount command value Q set by the PI control portion21, the heater generated heat amount setting portion22and cooled heat amount setting portion24set heat amounts to be generated in the heater5A and cooler6of the pertinent air conditioner unit30. Here, these settings are performed based on the heat supply amount command value Q, the number of air conditioner units, and the imparted order of a pertinent air conditioner unit in all of the air conditioner units. Therefore, between an air conditioner unit30A having a first order (this is assumed as the air conditioner unit (1)) and an air conditioner unit30A having a second order (this is assumed as the air conditioner unit (2)), the heat amount setting methods are partly different. This difference is based on the difference in setting pattern therebetween. The heat amount setting correspondence tables showing the setting patterns of the air conditioner units (1) and (2) are shown in Table and Table 4, respectively. Here, the variables N in Tables 3 and 4 are determined in the same way as in Table 2.

In Tables 3 and 4, the heat supply amount command values Q are classified into five cases. As can be seen from Tables 3 and 4, when the heat supply amount command value Q is not less than −5 kW and less than 0, it is only the air conditioner unit (1) that operates the cooler. At this time, the generated heat amount of the cooler6is −5 kW. When the heat supply amount command values Q is a minute cooled heat amount that is close to 0, the generated heat amount of the heater needs nearly 5 kW. Here, since the heater capacity of a single air conditioner unit is 2.5 kW, the two heaters5A of the two air conditioner units are to be used. That is, when the heat supply amount command value Q is not less than −5 kW and less than 0, the air conditioner unit (1) operates both the cooler6and heater5A, while the air conditioner unit (2) operates the heater5A alone. This provides a minute cooled heat amount. In the cases of the remaining four heat supply amount command values Q, the air conditioner units (1) and (2) exhibits the identical generated heat value.

When the heat supply amount command value Q is not less than −5 kW and less than 0, the temperatures of air discharged from the two air conditioner units (1) and (2) to exclusive ducts4A and4B, respectively, are different from each other. However, because these ducts merge with a common duct4on their way from the air conditioner units to the interior, the air from the two air conditioner units is mixed, so that there is no possibility of causing discomfort due to blowing winds with mutually different temperatures.

As stated above, since the vehicular air conditioner according to the second embodiment uses the air conditioner unit performing a heat generating operation and the air conditioner unit performing a cooled heat generating operation in combination, it is possible to obtain a target heat amount, though a single unit would not allow a minute cooled heat amount to be supplied.

Also, since the discharged air from a plurality of air conditioner units is supplied after having been mixed, it is possible to avoid causing discomfort due to blowing winds with mutually different temperatures.

Furthermore, the generated heat amounts of heat generators and cooled heat generator of each of the air conditioner units are set based on imparted order of the pertinent air conditioner unit in all air conditioner units, in addition to the number of the air conditioner units. Therefore, even when operations vary between the air conditioner units, it is possible to set generated heat amounts by the Tables.

In the above-described first and second embodiments, the air conditioner units constituting the vehicular air conditioner has been described by examples in which there are provided two air conditioner units with the same construction, but the air conditioner units may include three or more units. Also, each of the numbers of heat generators (such as heaters) and cooled heat generators (such as coolers) of the air conditioner units is not necessarily the same between the air conditioner units, but may be mutually different therebetween. Furthermore, some of the plurality of air conditioner units may include only the heat generator (such as heater) or the cooled heat generator (such as cooler).

INDUSTRIAL APPLICABILITY

The vehicular air conditioner according to the present invention has special effects on applications to various vehicles such as ordinary trains, buses, and the like. This is because, in spite of that these vehicles are different in the required air conditioning capability depending on a district where the vehicles run, the present vehicular air conditioner has the advantage of being able to easily cope with the difference in air conditioning capability by changing the number of air conditioner units. Also, the vehicular air conditioner according to the present invention can also be applicable to air conditioning for spaces other than vehicles.