Thermostat device

Details Thermostat device Thermostat device

2002-12-16

2004-07-13

Tapolcai, William E. (Department: 3744)

Automatic temperature and humidity regulation

Cooling radiator

Bypass

C236S06800R

Reexamination Certificate

active

06761321

ABSTRACT:

TECHNICAL FIELD
This invention relates to a thermostat device which is responsible for cooling an internal combustion engine, and more particularly to a thermostat device which has lower flow resistance than a conventional thermostat, which can control the operation of a valve body regardless of the cooling water temperature at the time of engine start-up, and which can achieve early warming of the engine, an improvement in fuel economy, and the prevention of overheating by being able to control the flow rate of the cooling water which circulates through a heating circuit or the like.
BACKGROUND ART
Thermostat devices disposed in the cooling systems of internal combustion engines and the like comprise a sensor case having an in-built thermal expansion body which perceives temperature changes in cooling water which fills the circulation channels of a cooling system and expands and contracts accordingly. The valve body opens and closes in response to volumetric change accompanying the expansion and contraction of the thermal expansion body, and thus the thermostat device functions to maintain cooling liquid at a predetermined temperature.
An example of a conventional thermostat device is illustrated in FIG.
7
. This thermostat device
1
A comprises a thermostat operating section
30
which serves as the driving section of the valve bodies inside valve housing
31
,
32
, which is constituted by two members. The thermostat operating section
30
is fixedly supported by the valve housing
32
, and a first valve body
33
and a second valve body
35
(bypass valve) are operated by an operating piston
9
which is built into the thermostat operating section
30
, whereby a main channel
34
and a bypass channel
36
are controlled.
The housing
37
of the thermostat operating section
30
is supported by a holder
39
, and this holder
39
surrounds the end of the housing
37
on the side at which the piston protrudes and the end of the opposite side in cap-form. The cap-form holder
39
is supported by the valve housing
32
.
A central region with a pot-shaped cross section is provided in the first valve body
33
, and the thermostat operating section
30
is disposed in this central portion. When the first valve body
33
is in a closed position, this central region, together with the holder
39
, blocks the main channel
34
.
A bolt
38
is provided as an extension in the axial direction of the operating piston (not shown) of the thermostat operating section
30
. A second valve body
35
(bypass valve) is attached to this bolt
38
by a sliding guide and opens and closes a bypass channel
36
. The second valve body
35
(bypass valve) is biased by a spring member
41
. The first valve body
33
is biased by a spring member
40
, and this spring member
40
is supported by the valve housing
31
.
The thermostat device
1
A constituted in this manner is disposed such that when cooling water from the engine
i
enters from the sleeve
42
, this cooling water circulates from the bypass channel
36
to the engine or through the sleeve
43
to the radiator
i
. Directly after engine start-up, the cooling water is at a low temperature, and therefore the cooling water which enters from the bypass
36
is returned directly to the engine. When the cooling water reaches a predetermined temperature following the completion of engine warm-up, wax inside the housing
37
senses this temperature and expands accordingly, thereby causing the operating piston (not shown) of the thermostat operating section
30
to expand. As a result of the expansion of the operating piston, the first valve body
33
falls against the urging force of the spring member
40
, thereby switching the main channel
34
from a blocked state to an open state, and the second valve body
35
(bypass valve) blocks the bypass channel
36
. As a result, the cooling water from the sleeve
42
passes through the sleeve
43
and flows into the engine.
In order to force the wax inside the housing
37
to expand, a heating part
44
is provided in the housing
37
, and this heating part
44
is caused to protrude from the valve housing
32
and connect to a superheater element
45
.
In such a conventional thermostat device
1
A, however, the housing
37
which serves as the cooling water temperature sensing portion is disposed inside the cooling liquid channels, and hence flow resistance in the cooling water entering from the sleeve
42
is large. It is therefore difficult to miniaturize the water pump which forces the cooling water to circulate.
Furthermore, during engine warm-up directly after engine start-up, the cooling water from the engine and the cooling water from the radiator become mixed in the vicinity of the housing
37
, which may produce a hunting phenomenon. When such a phenomenon is produced, the temperature of the cooling water which flows into the engine becomes unstable, making it difficult to improve fuel economy and achieve early warming. As a preventative measure, it has been necessary to adjust the structure of the valve housing
32
or to attach a current plate, also known as a baffle plate, directly before the housing
37
which serves as, the temperature sensing portion in order to mix the cooling water.
Moreover, when the thermostat device
1
A is disposed for inlet control, cooling water entering from the radiator is sometimes perceived, and as a result, malfunctions such as overheating may occur. Also, with the aim of compressing engine warm-up time, some devices are constituted such that the bypass valve body is closed and the flow rate of the cooling water flowing through the bypass channel is reduced to a minimum or halted completely, even when the temperature of the cooling water is low prior to engine warm-up, in order to avoid heat radiation from the bypass channel or from a heater radiator for heating the vehicle interior or various devices for controlling the engine provided at points in the bypass channel. However, since the flow of cooling water virtually ceases, heat spots may occur in the interior of the engine, or breakdowns of the engine or the thermostat may occur due to the negative suction pressure on the water pump.
If a further valve body is provided separately from the main valve body and bypass valve body in order to provide separate control for a heater radiator for heating the interior of the vehicle or various device circuits for controlling the engine, or if these circuits are integrated and controlled by the bypass valve body only, then the bypass channel has to be enlarged, whereupon problems arise such as construction becoming more complicated and the size of the device increasing.
DISCLOSURE OF THE INVENTION
The thermostat device according to the present invention has been devised in consideration of these problems, and it is an object of the present invention to provide a thermostat device in which early warming of an internal combustion engine can be achieved even at engine start-up time, in which fuel consumption can be reduced, and in which flow resistance of cooling water is low.
In order to solve the aforementioned problems, the thermostat device according to the present invention has a constitution in which a first valve body and a second valve body are removably supported on a main shaft which is supported by the distal end of a piston of a thermo-element which causes the first valve body and second valve body to open and close by sensing the temperature of cooling water, a temperature sensing section of the thermo-element is disposed so as to sense cooling water temperature by contacting only the cooling water from the engine outlet side without directly contacting the cooling water from the radiator outlet side, and a heat-generating element is attached to the temperature sensing section. Thus, in addition to the opening and closing of the first valve body and second valve body by the thermo-element in accordance with the temperature of the cooling water, the opening and closing of the first and second valve bodies are freely controlled by the application of a cur

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