Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
1999-09-01
2001-02-27
Tanner, Harry B. (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C236S00100H, C236S049300, C165S203000, C062S082000, C062S282000
Reexamination Certificate
active
06192698
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to vehicle air-conditioning systems wherein air flows in first and second passages can be controlled to different values, and particularly to a reduced-cost system in which a cooling degree detector is provided only in the first passage, and in which the degree of cooling taking place in the second passage is estimated.
2. Related Art
As disclosed in Japanese Unexamined Patent Publication No. Hei. 9-39544, air-conditioning systems wherein the inside of an air-conditioner case is partitioned into two passages to form separate driver seat side and passenger seat side passages are well known. In such a system, an evaporator and a heater core extend across both passages. A driver seat side air-mixing door is provided in the driver seat side passage, and a passenger seat side air-mixing door is provided in the passenger seat side passage so that conditioned air temperatures can be separately matched to the preferences of a driver and a passenger.
Also in such a system, a single air-conditioning fan is disposed in a non-partitioned upstream part of the air-conditioner case. Consequently, the air flows passing through the two passages are the same.
In the above-described system, the conditioned air blown to the driver seat side and the passenger seat side is independently temperature-controlled. However, because the conditioned air is blown at the same rate to each side, it is not possible to independently control the air flow rate.
In systems utilizing the above type of independent temperature control scheme, a cooling degree detector for detecting the degree to which air is being cooled by an evaporator is provided on the downstream side of the evaporator. This detector produces a detection signal that is used as air-conditioning control information. However, when as mentioned above air flows in the passages are controlled to different values, at times the flow through a part of the evaporator is large while the flow through the remainder of the evaporator is small, as conditioned air in each of the two separate passages passes through the evaporator.
Consequently, to obtain accurate air-conditioning control information for each of the two passages, a detector must be provided on the downstream side of the evaporator in each of the two passages because the air flow in each passage, as well as the degree to which the air is cooled in each passage, is different.
However, providing a separate detector for each passage increases the number of system parts, labor required to assemble the system, and system cost. On the other hand, in the above-described air-conditioning system, it is difficult to prevent frosting of the evaporator while preventing a windshield from being fogged.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide vehicle air-conditioning system with left/right independent temperature control that has one cooling degree detector in only one of the passages, and that estimates the cooling degree in the other passage.
It is an another object of the present invention to provide a vehicle air-conditioning system which prevents frosting of a cooling heat exchanger while preventing a windshield from being fogged.
To achieve this and other objects, the system of the present invention includes first and second air passages through which conditioned air is blown into first and second air conditioning zones, respectively. A heat exchanger is disposed in both the first and second passages, and cools air passing through it. A cooling degree detector disposed in the first passage detects a first cooling degree in the first passage. A cooling degree estimator then estimates a second cooling degree to which air is cooled in the second passage based on at least a first air flow blown through a first passage and a second air flow blown through the second passage, and the first cooling degree.
Because the degree to which air is cooled by heat exchanger in the second passage is estimated by the estimator, even though the cooling degree detector is only provided in the first passage, it is possible to determine the air cooling degree in the second passage.
Because a separate detector is not required for each passage, the number of system parts, labor required to assemble the system, and system cost are all reduced when compared to conventional dual-passage systems.
According to a further aspect of the present invention, an air-conditioning system includes a housing having first and second passages through which conditioned air is blown into first and second air-conditioning zones of the passenger compartment, respectively, a cooling heat exchanger disposed in both the first and second passages, a flow control member for controlling a flow rate of air in the first and second passages, a first cooling degree detector disposed in the first passage downstream from the cooling heat exchanger for detecting a first cooling degree of air in the first air passage, a second cooling degree detector disposed in the second passage downstream from the cooling heat exchanger for detecting a second cooling degree of air in the second air passage, and a control unit for controlling air blown into the passenger compartment. The control unit controls the flow control member in such a manner that a difference between an air amount passing through the first air passage and an air amount passing through the second air passage becomes smaller when any one of the first cooling degree and the second cooling degree is lower than a predetermined value. Therefore, when the cooling heat exchanger is possible to be frosted in one of the first and second air passages, temperature of air flowing through the other air passage between the first and second air passages is not greatly increased, thereby preventing the windshield from being fogged (or frosted).
Preferably, the control unit reduces cooling capacity of the cooling heat exchanger when any one of the first cooling degree and the second cooling degree is lower than a predetermined value. Therefore, it can prevent the cooling heat exchanger from being frosted while preventing the windshield from being fogged.
More preferably, the control unit controls the flow control member in such a manner that an air amount passing through an air passage where the cooling heat exchanger is possible to be frosted, between the first and second air passages, is corrected to be increased. Alternatively, an air amount passing through the other air passage, between the first and second air passages, is corrected to be decreased. Thus, it can further prevent the windshield from being fogged.
REFERENCES:
patent: 4406397 (1983-09-01), Kamata et al.
patent: 5086628 (1992-02-01), Hashimoto
patent: 5337802 (1994-08-01), Kajino et al.
patent: 5725052 (1998-03-01), Kawai et al.
patent: 6019288 (2000-02-01), Arold et al.
patent: 2-63216 (1990-05-01), None
patent: 6-247132 (1994-09-01), None
patent: 9-39544 (1997-02-01), None
Kakehashi Nobuharu
Ogawa Yoshiyuki
Samukawa Katsuhiko
Denso Corporation
Harness Dickey & Pierce PLC
Tanner Harry B.
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