Patent Application
20060067837
1. Field of the Invention
The present invention relates to an air conditioner for a vehicle and, particularly, to a compressor of an air conditioner for a vehicle and, more particularly, to control of a variable displacement compressor of an air conditioner.
2. Description of the Related Art
Some vehicle air conditioners comprise a variable displacement compressor. A variable displacement compressor is capable of properly changing its displacement in accordance with the load of an air conditioner, the operating state of a vehicle, etc., and has various advantages such as in temperature control, energy saving effect, etc. Further, a variable displacement compressor may be directly connected to an engine, which is the drive unit of a compressor and there is no need for it to be connected via a clutch etc. and, therefore, the number of parts can be reduced and is more advantageous in cost compared to the case where a fixed displacement compressor is used.
As a variable displacement compressor, a swash plate type is used widely.
In the prior art, there was a proposal regarding the structure of the shaft seal 19 (for example, refer to patent document 1). The structure of such a shaft seal is already known. In the prior art, when a vehicle is in operation and the compressor is off, the flow of the oil shown in
As describe above, when the compressor is in the off state and the revolution speed of the engine is high, the shaft seal is adversely affected because the temperature and the pressure around the shaft seal rise.
The wording “a state in which a compressor is off” in this specification means a state in which the flow rate of the refrigerant flowing through the air conditioner cycle is almost zero.
[Patent document 1] Japanese Unexamined Patent Publication (Kokai) No. 2002-364759
The present invention has been developed with the above-problems being taken into account, and an object thereof is to provide a compressor having a configuration for protecting a shaft seal and, more particularly, a variable displacement compressor for an air conditioner of a vehicle.
Another object of the present invention is to provide a control method capable of protecting a shaft seal of a compressor and, more particularly, of a variable displacement compressor for an air conditioner of a vehicle.
In order to attain the above-mentioned objects, in a first aspect of the present invention, an air conditioner comprises a variable displacement compressor for compressing a refrigerant and a control unit for controlling the compressor. The compressor is driven by an engine of a vehicle and is normally connected to the engine at all times. The control unit is characterized by controlling the compressor such that when the compressor is in an off state the compressor turns on and operates at predetermined time intervals T1 and intermittently (temporarily) during time T2, and the revolution speed thereof is equal to or higher than a predetermined revolution speed N.
With such a configuration, when a vehicle is in high-speed operation and the compressor is in the off state, during which the shaft seal of the variable displacement compressor of an air conditioner for a vehicle is adversely affected, the shaft seal is protected and therefore the compressor is protected as a result by turning on the compressor at predetermined time intervals and intermittently (temporarily).
A second aspect of the present invention, according to the above-mentioned first aspect, is characterized in that the compressor is a swash plate type.
According to the present aspect, the type of the compressor of the present invention is made more concrete.
A third aspect of the present invention according to either of the above-mentioned first and second aspects, is characterized in that the control unit preferably controls the compressor such that the compressor turns on and operates at the time intervals T1 being substantially equal to or longer than one minute and for the time T2 being substantially equal to or longer than one minute when the compressor is in the off state and the revolution speed of the compressor is equal to or higher than a predetermined revolution speed N, and that it is more preferable to control the compressor such that the compressor turns on and operates at the time intervals T1 being substantially equal to or longer than 10 minutes and for the time T2 being substantially equal to one minute.
According to the present aspect, an aspect is disclosed in which the control parameters of an air conditioner for a vehicle according to the present invention are made more concrete.
A fourth aspect of the present invention according to any one of the above-mentioned first to third aspects, is characterized in that the predetermined revolution speed N of the compressor is preferably substantially 6,000 rpm.
According to the present aspect, the revolution speed of the compressor, which is a control parameter of the compressor of an air conditioner for a vehicle according to the present invention, is made more concrete.
In a method for controlling an air conditioner for a vehicle according to a fifth aspect of the present invention, the air conditioner comprises a variable displacement compressor for compressing a refrigerant and a control unit for controlling the compressor. The control method is carried out by the control unit and the compressor of the air conditioner is driven by an engine of a vehicle and is normally connected to the engine at all times. The method for controlling an air conditioner for a vehicle is characterized by comprising the steps of: checking whether the revolution speed of the compressor is equal to or higher than a predetermined revolution speed N; checking whether the compressor is off; and turning on and operating the compressor at predetermined time intervals T1 and intermittently (temporarily) during time T2 when the compressor is in the off state, and the revolution speed of the compressor is equal to or higher than the predetermined revolution speed N.
With such a control method, when a vehicle is in high-speed operation and the compressor is in the off state, during which the shaft seal of the variable displacement compressor of an air conditioner for a vehicle is adversely affected, the shaft seal is protected and, therefore, the compressor is protected as a result by turning on the compressor at predetermined time intervals and intermittently (temporarily).
A sixth aspect of the present invention according to the above-mentioned fifth aspect, is characterized in that the compressor is a swash plate type.
According to the present aspect, the type of the compressor of the present invention is made more concrete.
In a seventh aspect of the present invention according to either of the above-mentioned fifth and sixth aspects, the control method is characterized in that it is preferable to control the compressor such that the compressor turns on and operates at the time intervals T1 being substantially equal to or longer than one minute and for the time T2 being substantially equal to or longer than one minute when the compressor is in the off state and the revolution speed of the compressor is equal to or higher than the predetermined revolution speed N, and that it is more preferable to control the compressor such that the compressor turns on and operates at the time intervals T1 which are substantially equal to or longer than 10 minutes and for the time T2 which are substantially equal to one minute.
According to the present aspect, an aspect is disclosed in which the control parameters of an air conditioner for a vehicle according to the present invention are made more concrete.
An eighth aspect of the present invention according to any one of the above-mentioned fifth to seventh aspects, is characterized in that the predetermined revolution speed N of the compressor is preferably substantially 6,000 rpm.
According to the present aspect, the revolution speed of the compressor, which is the control parameter of the compressor of an air conditioner for a vehicle according to the present invention, is made more concrete.
The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.
In the drawings:
An air conditioner for a vehicle in an embodiment of the present invention is explained in detail based on drawings.
An air conditioner for a vehicle 1 in an embodiment of the present invention comprises a variable displacement swash plate type compressor 10 shown in
First, the outline of the control of an air conditioner is explained with reference to
Next, the control of the air conditioner 1 in the present embodiment is explained in detail with reference to
When one minute of the time T1, during which the compressor 10 is on, elapses, the flow proceeds to step 50 (S50). In step 50, whether another compressor-on command, for example, a command to turn on an air conditioner, is issued, is checked. If a compressor-on command is not issued (NO), the flow proceeds to step 60 (S60). In step 60, the time T2, during which the compressor 10 is off, is checked. In the present embodiment, it is preferable for T2 to be substantially 10 minutes. If 10 minutes of T2 have not elapsed yet, the flow returns to step 50 and a compressor-on command is checked. If 10 minutes of T2 elapse in a state in which there is no compressor-on command, the flow returns to step 20 and the flow is repeated again from step 20. In this manner, the shaft seal 19 of the compressor 10 is lubricated and protected by turning on (ON) the compressor 10 periodically and intermittently (temporarily) when the revolution speed of the compressor 10 is high (equal to or higher than N) and the compressor is in the off state.
In the control flow in
In the above-mentioned explanation, the revolution speed N of the compressor is assumed to be 6,000 rpm, however, this value is determined properly depending on the type, capacity, etc., of the compressor and in this explanation, this value is suited to a specific concrete example and it is just an example to make the explanation easier to understand. Further, it will be apparent to those skilled in the art that the times T1 and T2 used in control may have a certain range. For example, T1 may be longer, such as two minutes, provided it is not shorter than one minute, however, one minute is more efficient and suitable. T2 may be longer provided it is not shorter than one minute, however, 10 minutes are more efficient and suitable. Further, T1 and T2 are determined properly depending on the specifications etc. of the compressor and it will be apparent to those skilled in the art that the suitable values should be changed depending on the type of the compressor, the type of the vehicle, etc. The concrete numerical values in the above-mentioned embodiments are suited to specific concrete examples and they are just examples to make the explanation easier to understand.
Next, the effects and functions of the above-mentioned embodiments are explained.
The following effect can be expected from the air conditioner in the above-mentioned embodiments of the present invention.
When the vehicle is in high-speed operation and the compressor is in the off state, during which the shaft seal of the variable displacement compressor of an air conditioner for a vehicle is adversely affected, the shaft seal is protected and therefore the compressor is protected as a result by turning on the compressor at fixed time intervals and intermittently (temporarily).
In the embodiments described above or shown in the accompanying drawings, the compressor of an air conditioner for a vehicle according to the present invention is explained as a swash plate type, however, the present invention is not limited to this and the present invention may be applied to a variable capacity compressor other than one of the swash plate type. In this case, the control target in the above-mentioned explanation is the control valve 42 of the compressor, however, the control target may be also changed, from the control valve 42, in accordance with the type of the target compressor.
In the above-mentioned explanation, the control of the present invention is incorporated in the vehicle control unit (ECU) and the control is carried out by the ECU, however, it may also be possible to incorporate the control of the present invention in another control unit other than the ECU and carry out the control thereby.
As described in the above-mentioned explanation, the control of the present invention is incorporated as part of the control of an air conditioner for a vehicle and, therefore, it may also be possible that the control procedure for another air conditioner, compressor, vehicle, etc., is incorporated in or added to the control flow in the above-mentioned embodiments and elements required for the control of an air conditioner or a compressor are incorporated.
The above-mentioned embodiments are only examples of the present invention and the present invention is not limited by the embodiments but is specified only by the claims described hereinafter, and embodiments other than the above-mentioned embodiments are also possible.
While the invention has been described by reference to specific embodiments chosen for the purposes of illustration, it should be apparent that numerous modifications could be made thereto, by those skilled in the art, without departing from the basic concept and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-279853 | Sep 2004 | JP | national |
