The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 28, 1993
Filed:
Mar. 24, 1992
Akhito Higashihara, Chiryu, JP;
Hiroshi Nonoyama, Toyota, JP;
Koichi Ito, Kariya, JP;
Michihiko Kamiya, Honda, JP;
Nippondenso Co., Ltd., Kariya, JP;
Abstract
A heater core 21 is connected to an engine cooling water line via an inlet passageway 43 and a return passageway 45. A first valve 25a is provided for controlling the amount of high temperature water introduced to the heater core 21, and a second valve 25b is provided for a re-circulation of low temperature water that has passed through the heater core, via a re-circulation passageway 46. The amount of high temperature engine cooling water supplied to the heater core 21 and the amount of low temperature cooling water from the heater core 21 passed through the return passageway 46 are controlled by an on-off manner control of the first and second valves 25a and 25b, respectively, and thus a ratio of a mixture of the high temperature water and the low temperature water, which corresponds to a time average value of the temperature of the cooling water introduced into the heater core, is controlled in accordance with a duty ratio of the on-off signals operating the valves 25 a and 25b. This on-off control of the valves 25a and 25b prevents a depositing of impurities at small valve gaps otherwise obtained between the valves and the respective valve seats. Furthermore, under particular conditions, the frequency of the on-off cycle can be reduced, to thereby prolong the service life of the device. A by-pass passageway 47 is provided for preventing water hammer.