Aspirator tube check valve assembly and method of continuously sensing vehicular interior compartment air temperature

An interior air temperature sensing system is provided for use with a vehicle interior compartment air temperature regulating system including an ambient air inlet duct, a blower housing connected to an air inlet duct and an air temperature modifier and a blower situated within the blower housing. The blower draws air from the air inlet duct under negative pressure and conveys the air at positive pressure past the air temperature modifier to the interior compartment. The air temperature sensing system includes an air temperature sensor and a venturi valve coupled to the negative pressure area of the blower. The valve includes an inlet port, and outlet port and a venturi section extending therebetween defining a point of minimum flow area, or valve seat. The valve also includes a diverter channel having a first port in communication with the inlet port and a second port in communication with the outlet port and a plug member situated between the inlet port and the outlet port and having a diameter greater than the valve seat. As the blower draws ambient air from the inlet duct, interior compartment air is drawn by the sensor and through the venturi valve and across the valve seat and out the outlet port. If the ambient air pressure exceeds the blower output pressure, the plug member is forced onto the valve seat to divert the oncoming air through the diverter channel creating a secondary venturi and continuing to draw air from the sensor, through the diverter channel to discharge elsewhere within the interior compartment.

TECHNICAL FIELD 
This invention relates to vehicular interior climate control systems, and 
particularly to an apparatus for continuously drawing interior compartment 
air through an air temperature sensing device. 
BACKGROUND 
In conventional electronic automatically controlled vehicular heating and 
air conditioning systems, it has been the practice for many years to 
include an air temperature sensing device for maintaining the interior air 
temperature at regulated preselected levels. This device is normally 
located behind the dash, reasonably close to the uppermost areas of the 
dashboard. Interior air is drawn through a vent in the dash and then 
through the air temperature sensor by means of establishing a negative 
pressure at the downstream end of the sensor. This is usually accomplished 
by connecting an air line from the outlet end of the sensor to a venturi 
valve. One such arrangement is shown in U.S. Pat. No. 2,316,619 issued to 
Raney, wherein the venturi valve is located within the downstream tube 
leading from the temperature sensor with air from the positive pressure 
end of a blower being passed through the venturi to create the area of 
negative pressure in communication with the sensor outlet. 
Another arrangement known in the prior art is to connect a similar venturi 
valve device to the positive pressure end of a blower housing. Each such 
system is fairly similar and each would apparently work equally well 
provided the positive pressure is controlled by the outlet of the blower. 
However, under certain conditions, namely at low blower speeds and vehicle 
speeds in excess of 15 to 20 miles per hour, the ambient air introduced 
into the system is at a higher pressure than the blower output, which 
destroys the negative pressure across the temperature sensor outlet, 
thereby rendering the air temperature sensing system inoperative. 
SUMMARY OF INVENTION 
This invention contemplates a vehicular interior compartment air sensing 
system which provides a continuous flow of interior air to a temperature 
sensor at all operating speeds of the blower and independently of the 
speed at which the vehicle is moving. 
This invention further contemplates a vehicular interior compartment air 
sensing system whereby interior air is constantly moved through the 
temperature sensor by providing a continuous source of negative pressure 
on the outlet end of the sensor. 
This invention further contemplates a vehicular interior compartment air 
sensing system which includes a venturi valve located at the negative 
pressure side of the blower assembly adjacent the air inlet duct. 
This invention further contemplates a vehicular interior compartment air 
sensing system wherein the above mentioned venturi valve includes a means 
for utilizing positive pressure air flow as may be created when the 
vehicle speed is far in excess of the relative blower speed in such a 
manner that the positive air flow passes through a second venturi valve 
means within the venturi valve to create a negative air pressure zone 
within the venturi valve itself and thereby continuously drawing air 
through the inlet end of the valve through the air temperature sensor 
outlet. 
The invention also contemplates a vehicle interior compartment air 
temperature regulating system including an ambient air inlet duct, a 
blower housing connected to the air inlet duct at one end and to an air 
temperature modifying means at the other end, the air temperature 
modifying means being one or both of a heater assembly and an evaporator 
coil assembly each of which may be selectively regulated by an air 
temperature regulating control means. A blower is situated within the 
blower housing at one end thereof for drawing air from the air inlet duct 
under negative pressure and conveying the air at positive pressure past 
the air temperature modifying means and to an air diverter which may 
divert air to selective portions of the interior compartment. An interior 
air temperature sensing system is also provided comprising an air 
temperature sensor and a venturi valve. The venturi valve is operatively 
coupled with the negative pressure area of said blower and includes an 
inlet port, an outlet port and a throughbore open to said inlet port and 
outlet port. The venturi valve has a primary venturi section therebetween 
defined by a converging wall portion terminating at a point of minimum 
flow area and defining a valve seat. A diverter channel is also provided 
including a first port in open communication with the inlet port at the 
upstream side of said valve seat and a second port in open communication 
with the outlet port at the other side of the valve seat. The venturi 
valve further includes a plug member of a diameter less than said port and 
greater than said valve seat, and means for retaining the plug member in 
the throughbore between the outlet port and the valve seat. The 
temperature sensor is operatively coupled to the venturi valve upstream of 
said inlet part. As the blower draws ambient air from the inlet duct, 
interior compartment air will be drawn through the sensor and then through 
the venturi valve across the venturi section and valve seat and out the 
outlet port to combine with the ambient air to be passed through the 
blower. If the ambient air pressure exceeds the blower output pressure, 
the resultant positive pressure through the outlet port will force the 
plug member onto the valve seat and thereby divert the oncoming air 
through the diverter channel creating a secondary venturi and continuing 
to draw air from the sensor, through the diverter channel, to discharge 
elsewhere within the interior compartment. 
The invention further contemplates a method of continuously drawing 
vehicular interior compartment air through an air temperature sensing 
means by utilizing the negative pressure at the inlet end of the blower 
during certain operating conditions and by converting within a diverter 
valve any positive pressure inlet to a source of negative pressure by 
providing the diverter valve with a supplementary venturi system. 
These and other objects and features of the invention will be readily 
appreciated by one of ordinary skill in the art from the following 
detailed description of the best mode for carrying out the invention when 
taken in connection with the following drawings.

BEST MODE FOR CARRYING OUT THE INVENTION 
Referring now to FIG. 1, there is illustrated the general configuration of 
a vehicular climatic control system consisting of an ambient air inlet 
duct extending from the front of the vehicle and leading in under the dash 
to a blower housing and air ducting system, shown generally by reference 
numeral 10. An air inlet duct 12 discharges into the blower housing 13 at 
one end thereof located proximate the blower 14 contained within the 
housing. Preferably, the blower 14 is of the squirrel cage type and 
generally oriented so as to rotate about an axis designated 16. 
At the discharge end of the blower 14 there is located a cut-off section 18 
within the housing over which the blower air is caused to pass. The 
cut-off section 18 leads to a positive pressure chamber 20 in the housing 
and vents to an evaporator coil system 22 and from there to a heater core 
assembly 24 and finally to an air discharge end 26. Heated or cooled air 
may be discharged therefrom through ducting sections 28 and 30 to various 
locations within the vehicle interior compartment. 
With continuing reference to FIG. 1, at the ambient air inlet end of the 
housing, at a portion of the ducting or housing which will be subjected to 
negative pressure at the inlet end of the blower, there is located a 
venturi valve member 34. Leading to the venturi valve member 34 from an 
inlet vent 42 mounted on the dashboard of the vehicle interior is an air 
line 36, which includes an air temperature sensing device 38 disposed 
along its length. 
In operation, it is the function of the blower 14 to draw in ambient air 
from the inlet duct and pass it through the housing, where the air 
temperature can be modified by separate controls on the air conditioning 
system, which will pass refrigerant through the evaporator coils, or 
through the heater core assembly 24 which will elevate the temperature of 
the incoming air. The temperature is regulated by controls (not shown) 
proximate to the occupant. The interior regulated air is then drawn 
through the vent 42 and over the temperature sensing device 38 to 
determine if the air temperature has reached the level as prescribed by 
the controls. Since the system functions best if a continuous flow of air 
passes through the temperature sensor, the outlet end 46 of the 
temperature sensing device 38 is connected to a venturi valve 34 located 
at the inlet end of the blower 14 which is subjected to negative pressure. 
In the preferred embodiment, the suction in the air line 36 draws air from 
the interior of the vehicle through the temperature sensor 38 and through 
the venturi valve 34 and then it is discharged to the incoming air being 
passed through the blower 14. As long as the vehicle is moving at a speed 
slow enough relative to the speed of the blower that the negative pressure 
is maintained, the temperature sensing system will operate as described 
above. However, should an increased vehicle speed cause the incoming air 
to overrun the capacity of the blower and thereby produce a positive air 
pressure condition at the inlet end of the blower, the venturi valve 34, 
in accordance with the present invention, is constructed such that the air 
will be rerouted through a supplemental venturi system and thereby 
continue to provide a negative pressure within the valve itself which in 
turn will continue to draw air through the temperature sensor 38. 
Referring now to FIG. 2, the venturi valve 34 is shown under normal flow 
conditions, i.e. when there exists a negative pressure at the inlet end of 
the blower. Preferably, the venturi valve 34 comprises a molded plastic 
valve body 50 having an inlet port 52 for receiving air from the 
temperature sensor 38 and an outlet port 54 connected to, and in open 
communication with, the interior of the blower housing 13. Extending 
between the inlet and outlet ports 52 and 54 is a throughbore 56 having a 
valve seat 58 formed approximately midway at the juncture of two 
oppositely converging conical wall sections 60, 62. A ball valve 64 is 
located within that portion of the throughbore 56 between the valve seat 
58 and the outlet port 54. To preclude the ball from passing out of the 
outlet port 54, there is provided a grid plate 66 having a plurality of 
vents disposed therein and being secured in a suitable manner to the 
outlet port. 
As shown in FIG. 2, the diameter of the ball valve 64 is substantially less 
than that of the inner diameter of the throughbore such that there is 
defined an effective flow area across the ball. This flow area is 
approximately equal to that of the flow area across the valve seat 58. In 
normal operation, the flow of air through the venturi valve 34 is as shown 
by the arrows 70, whereby incoming air from the air temperature sensor 38 
passes from the inlet port across the valve seat 58, over the ball valve 
64 and through the outlet port 54 to the blower housing. This is the 
manner of operation so long as there is a negative pressure at the outlet 
port 54 drawing air through the valve. 
With continuing reference to FIG. 2, it will be seen that the venturi valve 
34 also includes a secondary channel structure comprising a diverter 
channel 72 having a first port 74 open to the conical wall section 60 at 
the upstream end of the venturi valve. The diverter channel 72 also 
includes a second port 76 open to the conical wall section 62 at the 
downstream end of the valve seat 58. The diverter channel 72 terminates at 
a second and supplemental venturi valve portion 78 including a restricted 
flow throat 80 which is in open flow communication with the diverging 
conical wall section 62. 
Referring now to FIG. 3, in the event the vehicle speed overcomes the 
capacity of the blower to draw air, such that a positive pressure 
condition exists at the outlet port 54, the ball valve 64 will be caused 
to flow up into the conical wall section 62 and seat itself at the valve 
seat 58. This will cause the air from the blower housing 13 to pass 
through the second port 76 and out through the supplemental venturi 78. 
The negative pressure generated at the supplemental venturi is sufficient 
to divert air coming in from the inlet port 52 through the first port 74 
and out the diverter channel 72 and to be then discharged through the 
supplemental venturi to the vehicle anterior at a point under the dash. 
A second embodiment of the venturi valve is shown in FIG. 5. Like reference 
numerals are used to indicate the same elements as shown and described in 
the first embodiment of FIGS. 2-4. As shown in FIG. 5, the venturi valve 
includes an inlet port 52, an outlet port 54 and a throughbore 56 
connected thereto. The inlet and outlet ports are defined in part by the 
conical sections 60 and 62, respectively. At a point where the conical 
wall section 62 joins the throughbore 56, there is formed a valve seat 58. 
A ball valve 64 resides within the conical wall section 62 between the 
outlet port 54 and the valve seat 58. It is maintained within this area by 
means of a pin 86 which passes through the outlet port and is secured to 
the valve body 50. First port 74 and second port 76 are in open 
communication with the conical wall sections 60 and 62, respectively, and 
lead to a diverter channel 72 and thence to a discharge end 90. At the 
juncture of the diverter channel section coming from the first port 74 and 
the diverter channel section coming from the second port 76 there is 
defined a supplemental venturi 78. As with the operation of the first 
embodiment, when positive pressure exists at the outlet port 54, the ball 
valve is forced against valve seat 58 which in turn forces air from the 
blower housing through the second port 76 and out the discharge end 84 of 
the diverter channel. This in turn causes a negative pressure at the 
venturi 78 and draws air in a continuous pattern and without interruption 
to flow through the temperature sensor (not shown). 
For comparative purposes, there is shown in FIG. 6 a prior art venturi 
valve arrangement. As illustrated, this venturi valve 100 includes an 
inlet port 102 located within the blower housing 104 and defining a 
venturi section by means of a conical wall section diverging toward a 
venturi throat 106 and thence through a throughbore 108 to an outlet end 
110. At the outlet end of the venturi valve and nearest the venturi throat 
section there is a branch member 112 having a throughbore 114 in open 
communication with the downstream end of the throughbore 108 at the 
downstream end of the throat section 106. As shown in FIG. 1 in the 
encircled dash line area, designated "A", the prior art venturi valve is 
located at the positive pressure end of the blower housing. Consequently, 
positive pressure air is forced through the inlet port 102 across the 
venturi throat 106 and out the outlet port 110. This creates a condition 
of negative pressure at the discharge end of the tube which in turn is 
connected with the outlet end of the temperature sensor (not shown). 
Consequently, air is drawn through the venturi valve at the inlet port 102 
in a continuous fashion so long as a regulated positive pressure is 
maintained across the venturi valve. At low blower speeds and a vehicle 
speed in excess of 15 to 20 miles per hour, it has been found that the air 
velocity across the valve exceeds this positive pressure limitation and as 
a result creates a positive pressure on the other side of the venturi 
valve which in turn interrupts the flow of air from the air temperature 
sensing device. 
It is understood, of course, that while the form of the invention herein 
shown and described constitutes the preferred embodiment of the invention, 
it is not intended to illustrate all possible forms thereof. It will also 
be understood that the words used are words of description rather than 
limitation, and that various changes may be made without departing from 
the spirit and scope of the invention as disclosed.