CN113412385B

CN113412385B - Air conditioner for vehicle

Info

Publication number: CN113412385B
Application number: CN202080012839.0A
Authority: CN
Inventors: 石関徹也; 星野明洋
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 2019-02-13
Filing date: 2020-01-17
Publication date: 2023-04-04
Anticipated expiration: 2040-01-17
Also published as: CN113412385A; DE112020000787T5; WO2020166273A1; JP2020133927A

Abstract

The time required for the initialization process is shortened. When the opening degree of the expansion valve (12) is greater than a threshold value (th 1) during a system stop (yes in S103), the threshold value (th 1) is set to a target opening degree (S104). Then, a pulse signal for turning off the stepping motor (13) to a target opening degree is applied (S105), and thereby an advance process for the next initialization process is performed.

Description

Air conditioner for vehicle

Technical Field

The present invention relates to an air conditioner for a vehicle.

Background

Since many electronic expansion valves driven by a stepping motor do not have a device capable of accurately detecting an absolute angle at the time of system startup, an initialization process for detecting a fully closed position is performed at the time of system startup, as shown in patent document 1. That is, the full-close position is detected by applying a pulse number that reliably keeps the electronic expansion valve fully closed at the time of system startup. Further, the initialization process may be performed by detecting the fully open position at the time of system startup.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-53908

Disclosure of Invention

Technical problems to be solved by the invention

In the case of the initialization process for detecting the fully closed position, for example, the electronic expansion valve is stopped in a state close to the fully open state, and when the electronic expansion valve is to be fully closed from the state close to the fully open state, the number of pulses increases, and the time until completion becomes long. Similarly, in the case of the initialization process for detecting the fully open position, the electronic expansion valve is stopped in a state close to the fully closed state, for example, and when the state close to the fully closed state is to be fully opened, the number of pulses increases, and the time until completion becomes long.

The technical problem of the invention is to shorten the time required by initialization processing.

Technical scheme for solving technical problems

An air conditioning device for a vehicle according to an aspect of the present invention includes:

an expansion valve that changes an opening degree according to a rotation angle of a stepping motor;

a start-time control unit that performs an initialization process for detecting a fully closed position of the expansion valve by applying a pulse signal for fully closing the expansion valve to the stepping motor at the time of system start; and

and a stop-time control unit that sets a first target opening degree between the fully-opened position and the fully-closed position and at a position where the opening degree is smaller than a current opening degree when the opening degree of the expansion valve is larger than a predetermined first threshold value between the fully-opened position and the fully-closed position at the time of a system stop, and performs an advance process for a next initialization process by applying a pulse signal for closing the stepping motor to the first target opening degree.

An air conditioning device for a vehicle according to another aspect of the present invention includes:

a start-time control unit that performs an initialization process for detecting a fully open position of the expansion valve by applying a pulse signal for fully opening the expansion valve to the stepping motor at the time of system start; and

and a stop-time control unit that sets a third target opening degree between the fully-opened position and the fully-closed position and at a position where the opening degree is larger than a current opening degree when the opening degree of the expansion valve is smaller than a predetermined third threshold value between the fully-opened position and the fully-closed position at the time of a system stop, and performs an advance process for a next initialization process by applying a pulse signal for opening the stepping motor to the third target opening degree.

Effects of the invention

According to the present invention, when the expansion valve is fully closed as the initialization process, the valve is closed to the first target opening degree when the system is stopped, and therefore, the time required for the next initialization process can be shortened. Similarly, in the case where the expansion valve is fully opened as the initialization process, the valve is opened to the third target opening degree when the system is stopped, and therefore, the time required for the next initialization process can be shortened.

Drawings

Fig. 1 is a diagram showing an air conditioner for a vehicle.

Fig. 2 is a flowchart showing the stop time control of the first embodiment.

Fig. 3 is a flowchart showing the startup control of the first embodiment.

Fig. 4 is a timing chart showing the opening degree of the expansion valve in the first embodiment.

Fig. 5 is a flowchart showing the stop time control of the second embodiment.

Fig. 6 is a flowchart showing the startup control of the second embodiment.

Fig. 7 is a timing chart showing the opening degree of the expansion valve in the second embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each drawing is a schematic diagram, and may be different from an actual member. The following embodiments are intended to exemplify an apparatus and a method for embodying the technical idea of the present invention, and the structure is not specified to the following structure. That is, the technical idea of the present invention can be variously changed within the technical scope described in the claims.

First embodiment

Structure (of the related Art)

Fig. 1 is a diagram showing a part of an air conditioner for a vehicle.

The air conditioner 11 for a vehicle is a heat pump system installed in an automobile, and includes an expansion valve 12, a stepping motor 13, and a controller 14. Further, the other components included in the vehicle air conditioner 11 will not be described.

The expansion valve 12 is a member that reduces the pressure of a high-pressure heat medium, which is a liquid phase, to a low-pressure heat medium that is easily vaporized by blowing the heat medium in a mist form, and is an electronically controlled expansion valve that changes the opening degree from the fully closed position to the fully open position in accordance with the rotation angle of the stepping motor 13. A structural stop is provided at the fully open position to prevent further opening.

The stepping motor 13 is a member driven by an input pulse signal, obtains a rotation angle proportional to the number of pulses, and maintains a stop position when no pulse is input. The number of pulses required to open the expansion valve 12 from the fully closed position to the fully open position, or to close the expansion valve 12 from the fully open position to the fully closed position is, for example, 500 pulses. The stepping motor 13 determines the rotation speed according to the stepping angle and the frequency.

The controller 14 is constituted by, for example, a microcomputer, and applies a pulse signal to the stepping motor 13 via a drive circuit not shown. The controller 14 is a means for performing an initialization process for detecting the fully closed position at the time of system startup, and includes a stop-time control unit 15 and a start-time control unit 16.

The stop time control unit 15 performs an advance process for the next initialization process when the system is stopped.

Here, the stop control performed by the stop control unit 15 will be described.

Fig. 2 is a flowchart showing the stop time control of the first embodiment.

The stop control is started when the system is stopped, that is, when the ignition switch is turned off. Even if the ignition switch is turned off, electric power is supplied to the vehicle air conditioner 11 until the predetermined time Ts elapses. The time Ts is, for example, several tens of seconds to several minutes, and is longer than at least the time for completing the advance processing performed in the stop time control.

First, in step S101, it is determined whether or not the initialization process is to be performed at the next system start, that is, at the time of turning on the ignition switch. The initialization process is performed not every time at the system start-up but at a frequency of one out of a plurality of times (for example, two to five times). If the initialization process is not intended at the next system startup, the process does not need to be advanced with respect to the initialization process, and the process proceeds to step S102. On the other hand, when the initialization process is to be performed at the next system startup, the process proceeds to step S103 in order to perform an advance process with respect to the initialization process.

In step S102, the current opening degree of the expansion valve 12, that is, the current rotation angle of the stepping motor 13 is stored in the memory, and then the routine returns to a predetermined main routine. The current opening degree of the expansion valve 12 is determined based on the pulse signal input to the stepping motor 13.

In step S103, it is determined whether or not the current opening degree of the expansion valve 12 is greater than a predetermined threshold value th1 (first threshold value). The threshold th1 is, for example, a median value between the fully closed position and the fully open position. Here, the pulse width is set to a position opened by 250 pulses from the fully closed position or a position closed by 250 pulses from the fully open position. Here, when the current opening degree of the expansion valve 12 is greater than the threshold value th1, the process proceeds to step S104. On the other hand, when the current opening degree of the expansion valve 12 is equal to or less than the threshold th1, the process proceeds to step S106.

In step S104, the target opening degree (first target opening degree) of the expansion valve 12 is set to the threshold th1.

Next, in step S105, a pulse for closing the expansion valve 12 to the target opening degree is output to the stepping motor 13, and the process then proceeds to step S102. That is, a pulse is applied that rotates the expansion valve 12 in the closing direction by the difference between the current opening degree and the threshold th1. The rotation speed of the stepping motor 13 is constant.

In step S106, it is determined whether or not the current opening degree of the expansion valve 12 is greater than a predetermined threshold value th2 (second threshold value). The threshold value th2 is a value between the threshold value th1 and the fully closed position, and can be regarded as a lower limit value at which the expansion valve 12 is reliably opened. Here, for example, the position is opened by 50 pulses from the full-close position, or closed by 200 pulses from the threshold th1. Here, when the current opening degree of the expansion valve 12 is larger than the threshold value th2, the process proceeds directly to step S102. On the other hand, when the current opening degree of the expansion valve 12 is equal to or less than the threshold th2, the process proceeds to step S107.

In step S107, the target opening degree (second target opening degree) of the expansion valve 12 is set to the threshold th2.

Next, in step S108, a pulse for opening the expansion valve 12 to the target opening degree is output to the stepping motor 13, and the process then proceeds to step S102. That is, a pulse is applied that rotates in the opening direction by the amount of the difference between the current opening degree and the threshold th2. The rotation speed of the stepping motor 13 is constant.

The above is the stop time control.

The startup control unit 16 performs initialization processing at the time of system startup.

Here, the startup control performed by the startup control unit 16 will be described.

Fig. 3 is a flowchart showing the startup control of the first embodiment.

The start-time control is started when the system is started, that is, when the ignition switch is turned on.

First, in step S111, the current opening degree of the expansion valve 12, that is, the rotation angle of the stepping motor 13 is read from the memory.

Next, in step S112, it is determined whether or not the initialization process is performed at the time of the present system start. When the initialization process is not performed, the program returns to the predetermined main routine. On the other hand, when the initialization process is performed, the process proceeds to step S113.

In step S113, a pulse for setting the current opening degree of the expansion valve 12 to the full close is set. Specifically, the pulse is for closing the expansion valve 12 by an amount that adds the predetermined value α to the current opening degree. The predetermined value α may be a fixed value from several tens of pulses to several hundreds of pulses, or may be a variable value of about several tens of percent of the current opening degree.

Next, in step S114, a pulse for fully closing the expansion valve 12 is output to the stepping motor 13. The rotation speed of the stepping motor 13 is constant.

Next, in step S115, the stop position of the stepping motor 13 is detected as the fully closed position of the expansion valve 12, and the routine returns to the predetermined main routine.

The above is the start-time control.

Action

Next, the main operational effects of the first embodiment will be described.

Since the expansion valve 12 driven by the stepping motor 13 has no means for accurately detecting the absolute angle at the time of system start, initialization processing for detecting the fully closed position is performed at the time of system start in which the ignition switch is turned on. That is, a pulse for setting the current opening degree of the expansion valve 12 to the full close is set (S113), and is output to the stepping motor 13 (S114). At this time, in order to be able to be fully closed reliably, a pulse for closing the expansion valve 12 to an amount that adds the predetermined value α to the current opening degree is applied. In this way, the full-close position of the expansion valve 12 is periodically detected, thereby improving the control accuracy.

When the system in which the ignition switch is turned off is stopped, an advance process for the next initialization process is performed. That is, when the opening degree of the expansion valve 12 is larger than the threshold value th1 during the system stop (yes in determination at S103), the threshold value th1 is set to the target opening degree (S104). Then, by applying a pulse signal for turning off the stepping motor 13 to a target opening degree (S105), an advance process for the next initialization process is performed. Accordingly, in the next initialization process, the expansion valve 12 may be fully closed from the threshold th1, and therefore, the required time can be shortened.

When the expansion valve 12 is equal to or smaller than the threshold th1 (no in determination in S103) and larger than the threshold th2 (yes in determination in S106) during the system stop, the expansion valve 12 does not need to be further closed. Therefore, the pulse signal is not applied to the stepping motor 13, and the expansion valve 12 is maintained at the current opening degree. In this way, the stepping motor 13 cannot be driven in advance to perform the initialization processing, and therefore, an increase in the number of operations can be suppressed. In the next initialization process, the expansion valve 12 may be fully closed from the opening degree equal to or smaller than the threshold th1, and therefore, the required time is short.

Further, it is not desirable to fully close or substantially fully close the expansion valve 12 during the system stop. This is because when the expansion valve 12 is fully closed, a closed circuit is formed in the refrigeration cycle, and it is difficult to absorb a pressure change accompanying a temperature change. Therefore, when the expansion valve 12 is equal to or smaller than the threshold value th2 while the system is stopped (no in determination of S106), the threshold value th2 is set to the target opening degree (S107), and a pulse signal for opening to the target opening degree is applied to the stepping motor 13 (S108). This can reliably prevent the formation of a closed circuit in the refrigeration cycle during the system stop.

In the figure, (a) shows a case where the system is stopped in a state where the opening degree of the expansion valve 12 is larger than the threshold value th1, and the example is shown by a thick solid line and the comparative example is shown by a thick broken line. Here, a case where the advance processing for the initialization processing is not performed is taken as a comparative example. In the comparative example, when the ignition switch is turned off at time t11, the opening degree of the expansion valve 12 can be maintained since the advance process is not performed. When the ignition switch is turned on at time t13, the initialization process is started from time t13, and the expansion valve 12 is started to close toward the fully closed position. The expansion valve 12 is fully closed at time t15, and the initialization process is completed by detecting the fully closed position.

On the other hand, in the embodiment, at the time point t11, if the ignition switch is turned off, the advance process is started, and the expansion valve 12 is started to be closed toward the threshold th1. When the expansion valve 12 reaches the threshold value th1 at the time point t12, the advancing process is completed and the opening degree of the expansion valve 12 can be maintained. When the ignition switch is turned on at time t13, the initialization process is started from time t13, and the expansion valve 12 is started to close toward the fully closed position. The expansion valve 12 is fully closed at time t14, and the initialization process is completed by detecting the fully closed position. By performing the advance processing for the initialization processing in this way, the time point when the initialization processing is completed can be shortened from t15 to t14.

In the figure, (b) is a case where the system is stopped in a state where the opening degree of the expansion valve 12 is smaller than the threshold value th1 and larger than the threshold value th2. When the ignition switch is turned off at time t21, the opening degree of the expansion valve 12 can be maintained. When the ignition switch is turned on at time t22, the initialization process is started from time t22, and the expansion valve 12 is started to close toward the fully closed position. The expansion valve 12 is fully closed at time t23, and the initialization process is completed by detecting the fully closed position. In this way, when the expansion valve 12 has been closed to some extent at the time point when the system is stopped, since the stepping motor 13 cannot be driven in advance to face the initialization process, an increase in the number of operations can be suppressed.

In the drawing, (c) represents a case where the system is stopped in a state where the opening degree of the expansion valve 12 is smaller than the threshold value th2. When the ignition switch is turned off at time t31, the expansion valve 12 starts to open toward the threshold th2. When the expansion valve 12 reaches the threshold value th2 at time t32, the opening degree of the expansion valve 12 is maintained. When the ignition switch is turned on at time t33, the initialization process is started from time t33, and the expansion valve 12 is started to close toward the fully closed position. The expansion valve 12 is fully closed at time t34, and the initialization process is completed by detecting the fully closed position. As described above, when the expansion valve 12 is at the fully closed or substantially fully closed position at the time point when the system is stopped, the valve is opened to the threshold th2, whereby the closed circuit can be reliably prevented from being formed in the refrigeration cycle.

In addition, the initialization processing is not performed every time the system is started, but performed at a frequency at which the initialization processing is performed once at the time of the system start many times. In the vehicle air conditioner 11, the start and stop of the system are frequently repeated, and if the expansion valve 12 is fully closed by the initialization process, the durability of the valve seat and the valve body may be affected. Therefore, by performing the initialization process at certain intervals, degradation of the expansion valve 12 can be suppressed.

Further, only when the initialization process is performed at the next system start-up, the advance process for the initialization process is performed. This prevents unnecessary advance processing.

Modifications of the invention

In the first embodiment, the threshold value th1 is set as the target opening degree when the opening degree of the expansion valve 12 is larger than the threshold value th1, but the present invention is not limited thereto. For example, a value smaller than the threshold th1 may be set as the target opening degree. If the opening degree can be closed to a certain extent from the current opening degree, a value larger than the threshold th1 may be set as the target opening degree. That is, if the opening degree is smaller than the opening degree at the time of system stop and is larger than the threshold th2, an arbitrary value can be set as the target opening degree.

In the first embodiment, the threshold value th1 is set to the target opening degree when the expansion valve 12 is larger than the threshold value th2, but the present invention is not limited thereto. For example, a value larger than the threshold th2 may be set as the target opening degree. That is, if the value is within a range smaller than the threshold th1 and larger than the threshold th2, an arbitrary value can be set as the target opening degree.

Second embodiment

Structure (A)

The second embodiment performs an initialization process for detecting the fully open position.

Here, the device configuration and the technical idea are the same as those of the first embodiment except that the position of detection in the initialization processing is different, and therefore detailed description of common parts is omitted.

Since the expansion valve 12 is provided with a structural stopper at the full open position to prevent further opening, the full open position is detected by applying a pulse to the stepping motor 13 until the spool reliably abuts against the stopper.

Fig. 5 is a flowchart showing the stop time control of the second embodiment.

First, in step S201, it is determined whether or not the initialization process is to be performed at the next system start, that is, at the time of turning on the ignition switch. If the initialization process is not intended to be performed at the next system startup, the process does not need to be advanced with respect to the initialization process, and therefore the process proceeds to step S202. On the other hand, when the initialization process is to be performed at the next system startup, the process proceeds to step S203 to perform an advance process with respect to the initialization process.

In step S202, the current opening degree of the expansion valve 12, that is, the current rotation angle of the stepping motor 13 is stored in the memory, and then the routine returns to a predetermined main routine. The current opening degree of the expansion valve 12 is determined based on the pulse signal input to the stepping motor 13.

In step S203, it is determined whether or not the current opening degree of the expansion valve 12 is smaller than a predetermined threshold value th3 (third threshold value). The threshold th3 is, for example, a central value between the fully-closed position and the fully-open position. Here, the pulse width is set to a position opened by 250 pulses from the fully closed position or a position closed by 250 pulses from the fully open position. Here, when the current opening degree of the expansion valve 12 is smaller than the threshold th3, the process proceeds to step S204. On the other hand, when the current opening degree of the expansion valve 12 is equal to or greater than the threshold th3, the process proceeds directly to step S202.

In step S204, the target opening degree (third target opening degree) of the expansion valve 12 is set to the threshold value th3.

Next, in step S205, a pulse for opening the expansion valve 12 to the target opening degree is output to the stepping motor 13, and the process then proceeds to step S202. That is, a pulse is applied that rotates in the opening direction by the amount of the difference between the current opening degree and the threshold th3. The rotation speed of the stepping motor 13 is constant.

The above is the stop time control.

Fig. 6 is a flowchart showing the startup control of the second embodiment.

First, in step S211, the current opening degree of the expansion valve 12, that is, the rotation angle of the stepping motor 13 is read from the memory.

Next, in step S212, it is determined whether or not the initialization process is performed at the time of the present system start. When the initialization process is not performed, the program returns to the predetermined main routine. On the other hand, when the initialization process is performed, the process proceeds to step S213.

In step S213, a pulse for setting the current opening degree of the expansion valve 12 to the full close is set. Specifically, a value obtained by subtracting the current opening degree from the movable range from the fully open position to the fully closed position is set as the current closing degree, and the pulse is a pulse for opening the expansion valve 12 by an amount obtained by adding the predetermined value α to the current closing degree. The predetermined value α may be a fixed value of about several tens of pulses to several hundreds of pulses, or may be a variable value of about several tens of percent of the current closure rate.

Next, in step S214, a pulse for fully closing the expansion valve 12 is output to the stepping motor 13. The rotation speed of the stepping motor 13 is constant.

Next, in step S215, the position at which the stepping motor 13 is stopped is detected as the full open position of the expansion valve 12, and the routine returns to the predetermined main routine.

The above is the start-time control.

Action

Next, the main operational effects of the second embodiment will be described.

Since the expansion valve 12 driven by the stepping motor 13 has no means for accurately detecting the absolute angle at the time of system start, initialization processing for detecting the fully open position is performed at the time of system start when the ignition switch is turned on. That is, a pulse for setting the current opening degree of the expansion valve 12 to full opening is set (S213), and is output to the stepping motor 13 (S214). At this time, in order to enable the full closure reliably, a pulse for opening the expansion valve 12 to an amount that adds the predetermined value α to the current closure degree is applied. In this way, the control accuracy is improved by periodically detecting the fully open position of the expansion valve 12.

When the system in which the ignition switch is turned off is stopped, an advance process for the next initialization process is performed. That is, when the opening degree of the expansion valve 12 is smaller than the threshold th3 during the system stop (yes in S203), the threshold th3 is set to the target opening degree (S204). Then, by applying a pulse signal for turning on the stepping motor 13 to the target opening degree (S205), an advance process for the next initialization process is performed. In this way, in the next initialization process, the expansion valve 12 only needs to be fully opened from the threshold th3, and therefore, the required time can be shortened.

When the expansion valve 12 is equal to or higher than the threshold th3 during the system stop (no in S203), the expansion valve 12 does not need to be opened any more. Therefore, the pulse signal is not applied to the stepping motor 13, and the expansion valve 12 is maintained at the current opening degree. In this way, the stepping motor 13 cannot be driven in advance to perform the initialization processing, and therefore, an increase in the number of operations can be suppressed. In the next initialization process, the expansion valve 12 may be fully opened from the opening degree equal to or larger than the threshold th3, and therefore, the required time is short.

In the initialization process for detecting the fully open position, even if the expansion valve 12 is at the fully open position or substantially the fully open position during the system stop, no closed circuit is formed in the refrigeration cycle, and therefore, there is no problem. Therefore, the processing corresponding to steps S106 to S108 in the first embodiment described above is not required.

In the figure, (a) shows a case where the system is stopped in a state where the opening degree of the expansion valve 12 is smaller than the threshold th3, and the example is shown by a thick solid line and the comparative example is shown by a thick broken line. Here, a case where the advance processing for the initialization processing is not performed is taken as a comparative example. In the comparative example, when the ignition switch is turned off at time t41, the opening degree of the expansion valve 12 can be maintained since the advance process is not performed. When the ignition switch is turned on at time t43, the initialization process is started from time t43, and the expansion valve 12 is opened toward the fully open position. The expansion valve 12 is fully opened at time t45, and the initialization process is completed by detecting the fully opened position.

On the other hand, in the embodiment, at the time point t41, if the ignition switch is turned off, the advance process is started, and the expansion valve 12 is started to be opened toward the threshold th3. If the expansion valve 12 reaches the threshold value th3 at the time point t42, the advancing process is completed, and the opening degree of the expansion valve 12 is maintained. When the ignition switch is turned on at time t43, the initialization process is started from time t43, and the expansion valve 12 starts to be opened toward the fully opened position. The expansion valve 12 is fully opened at time t44, and the initialization process is completed by detecting the fully opened position. By performing the advance processing for the initialization processing in this way, the time point when the initialization processing is completed can be shortened from t45 to t44.

In the figure, (b) is a case where the system is stopped in a state where the opening degree of the expansion valve 12 is larger than the threshold th3. When the ignition switch is turned off at time t51, the opening degree of the expansion valve 12 is maintained. When the ignition switch is turned on at time t52, the initialization process is started from time t52, and the expansion valve 12 is opened toward the fully open position. The expansion valve 12 is fully opened at time t53, and the initialization process is completed by detecting the fully opened position. In this way, when the expansion valve 12 has been opened to some extent at the time point when the system is stopped, since the stepping motor 13 cannot be driven in advance to face the initialization process, an increase in the number of operations can be suppressed.

Other operational effects are the same as those of the first embodiment.

Modifications of the examples

In the second embodiment, the threshold value th3 is set to the target opening degree when the opening degree of the expansion valve 12 is smaller than the threshold value th3, but the present invention is not limited thereto. For example, a value larger than the threshold th3 may be set as the target opening degree. If the opening degree can be slightly opened from the current opening degree, a value smaller than the threshold th3 may be set as the target opening degree. That is, if the opening degree is larger than the range of the opening degree when the system is stopped, an arbitrary value can be set as the target opening degree.

While the foregoing has been described with respect to a limited number of embodiments, it will be appreciated by those skilled in the art that variations may be made in the embodiments described above without departing from the scope of the claims set forth below.

(symbol description)

11 \8230, vehicle air conditioner 12 \8230, expansion valve 13 \8230, step motor 14 \8230, controller 15 \8230, stop control part 16 \8230andstart control part.

Claims

1. An air conditioning device for a vehicle, comprising:

a start-time control unit that performs an initialization process for detecting a fully closed position of the expansion valve by applying a pulse signal to the stepping motor to fully close the expansion valve at system start-up; and

a stop time control unit that sets a first target opening degree between a fully open position and a fully closed position and at a position where the opening degree is smaller than a current opening degree when an opening degree of the expansion valve is larger than a predetermined first threshold value between the fully open position and the fully closed position at a time of a system stop, and applies a pulse signal for closing the stepping motor to the first target opening degree to advance the initialization process for the next time,

the stop-time control unit sets a second target opening degree between the first threshold value and the full-close position and at a position where the opening degree is larger than a current opening degree when the opening degree of the expansion valve is smaller than a predetermined second threshold value between the first threshold value and the full-close position at the time of a system stop, and applies a pulse signal for opening the stepping motor to the second target opening degree.

2. The air conditioning device for vehicles according to claim 1,

the first target opening degree is the first threshold value.

3. The air conditioner for vehicles according to claim 1,

the stop-time control unit does not apply a pulse signal to the stepping motor to maintain the current opening degree of the expansion valve when the opening degree of the expansion valve is smaller than the first threshold value during a system stop.

4. A vehicular air-conditioning apparatus according to claim 2,

5. The air conditioning device for vehicle as claimed in any one of claims 1 to 4,

the second target opening degree is the second threshold value.

6. The air conditioning device for vehicle as claimed in any one of claims 1 to 4,

the second threshold value is a lower limit value that can be regarded as the expansion valve being reliably opened.

7. The vehicle air-conditioning apparatus according to any one of claims 1 to 4,

the start-time control unit does not perform the initialization processing every time the system is started, but performs the initialization processing at a frequency at which the initialization processing is performed once at the time of a plurality of times of system start.

8. A vehicular air-conditioning apparatus according to claim 7,

the stop time control unit performs the advance processing only when the initialization processing is performed at the next system start-up.