Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
  • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
  • B60K15/03—Fuel tanks
  • B60K15/035—Fuel tanks characterised by venting means

Definitions

• the present invention relates to a device for equalizing subatmospheric pressure in a container with a fluid medium, comprising an electromagnetic venting valve disposed between the interior of the container and an outlet from the con- tainer, and a control circuit connected for controlling the valve with a pressure sensor arranged to sense the sub- atmospheric pressure in the container and provide a signal to the control circuit, and to open the venting valve at a certain pre-determined subatmospheric pressure.
• Pressure monitoring systems with venting valves of this type are used in a wide range of applications. In order for these systems to work, they must be constantly connected to opera ⁇ ting voltage. These systems are thus not suitable for use in monitoring subatmospheric pressure in fuel tanks in vehicles where the current must be broken when the vehicle is not in operation.
• the present invention is directed to the development of a system for pressure monitoring, in particularly monitoring of subatmospheric pressue for u ⁇ e in particular, but not e :- clusively, for monitoring and compensating subatmospheric pressure in fuel tanks for motor vehicles to prevent deforma ⁇ tion caused by partial vacuum in the tank.
• the purpose of the present invention is in general to provide a device of the type described by way of introduction, which can be used in containers in which the partial vacuum arising in the fluid medium due to the dropping temperature can be equalized even if a switch for the control circuit governing the venting valve has been switched off.
• control circuit is connected to a current source via a manually operated switch, and in that a separate circuit with a temperature controlled switch is coupled in parallel to the manual switch.
• Such a device applied to an automobile with a low pressure sensor makes it possible for the control circuit, even though the automobile is parked and the ignition is turned off, to open the venting valve and equalize the partial vacuum in the tank when the fuel cools in the parked car.
• Figure 1 shows a circuit diagram of a device according to the invention.
• FIG. 2 shows a cross-section through a pressure sensor, particularly designed to be used in a device according to the invention
• Figure 3 is a partially cut-away plan view of the pressure sensor of Figure 2.
• 1 designates an electro- magnetically controlled valve
• 2 designates a venting hose to a tank 3, e.g. a fuel tank in a car.
• the valve 1 is opened and closed by a relay 4, which is controlled by a control circuit containing a transistor 5 and the pressure sensor 6 including an LED 7 and an LDR resistor 8.
• the valve 1 is open, the tank is connected via the hose 2 to the atmosphere or to a container under atmospheric pressure, e.g. a filter with activated charcoal.
• the pressure sensor 6 provides a low voltage at the point 9 by virtue of the fact that the resistance of the LDR resistor is low, e.g. about 600a.
• the relay 4 is open and the valve 1 is closed.
• the resistance in the resistor 8 rises to about 0.5Ma, thereby increasing the voltage at the point 9 so that as the switch 10, which can be an ignition lock, is turned on, current will be conducted through the relay 4 and the collector emitter path of the transistor, thus activating the relay and opening the valve 1.
• the valve 1 will return to its closed position, and this takes place when the voltage at the transistor base drops as the resistance in the LDR resistor drops.
• an extra switch circuit 11 is arranged in parallel to the switch 10, according to the invention.
• This circuit contains, inter alia, a tyristor 12, an NTC resistor 13, and a resistor 14 serving as a voltage divider.
• the resist ⁇ ance in the resistor 13 is high, and when the voltage has reached a certain level (0.8 volts), due to the resistance increase caused by the low temperature, the tyristor 12 will start to conduct and the relay circuit will conduct current. If the pressure sensor 6 in these circumstances indicates a partial vacuum, the valve 1 will open and vent the tank. As soon as the switch 10 is closed, the tyristor 12 will return to its rest position, and only be activated again at low temperature.
• the control circuit described is particularly suited for use in combination with a pressure sensor of the type shown in Figures 2 and 3. It shows a housing 20 of plastic, for examp ⁇ le, comprising a cylindrical wall portion 22, a circular bottom portion 23 and a circular cover 24, which are fixed to the cylinder 22.
• the bottom portion 3 is fixed to the cylin ⁇ der 22 with an intermediate 0-ring 25, and it defines to- gether with a bottom plate 26 made in one piece with the cylinder, a space which is divided into lower and upper chambers 28 and 29, respectively, by a thin membrane 30 stretched between the lower edge of the cylinder 22 and the bottom portion 23.
• the bottom plate 26 is provided with a bracket 31 and a pair of protecting walls 32, 33 with circular holes 34, 35.
• the LED 7 is fixed to the bottom plate 26 in front of the opening 34
• the LDR resistor 8 is fixed to the bottom plate in front of the opening 35.
• a semaphore-like arm 38 is pivotally mounted in a shaft 39 carried by the bracket 31 and is biased by a spring 40 towards the plate 26.
• the arm 38 has an outer screening portion 41 lying between the screen walls 32, 33, and which, in its position shown in Figure 2 with solid lines, covers the openings 34, 35. Furthermore, the arm 38 has approximately in its middle a heel 41 which extends through an opening 42 in the plate 26 and is held in contact with the membrane 30 by the spring 40.
• a tube 43 with a channel 44 leading into the lower chamber 28 is intended to be connected to the container where the pressure is to be monitored, e.g. the expansion space in a fuel tank for a motor vehicle.
• the LDR resistor 8 can be a resistor, in which the resistance can be changed from about 0.5MQ in the dark to about 600c at full illumination.
• the space above the bottom plate 26 is ventilated to the surroundings, so that the atmospheric pressure prevails in this space.
• the membrane 40 will bulge upwards or down ⁇ wards depending on whether there is overpressure or subat ⁇ mospheric pressure, and the arm 38 can swing between the position shown with solid lines to the position shown with dash-dot lines.
• the cooperating components i.e.
• the membrane 30, the arm 38 and the spring 40 can be adapted to each other so that the arm 38 assumes the position shown with solid lines when there is a subatmospheric pressure of about 0.5 kPa, whereupon the LDR resistor is kept in the dark.
• the central portion of the membrane is moved upwards, thus swinging the arm 18 up.
• the screening portion 41 of the arm has been moved away so that the LDR resistor is once again fully illu i- nated, the resistance in the resistor 8 will drop and the control circuit will brake the current to the relay 4, where ⁇ upon the venting valve 1 is closed.
• the device described contains simple and inexpensive com- ponents requiring very little space. Due to its very small space requirements, it can be integrated with other com ⁇ ponents, e.g. a level sensor for the fuel tank.
• the pressure sensor with the electronic control circuit and the venting valve can be manufactured at very low cost.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)
• Control Of Vehicle Engines Or Engines For Specific Uses (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20381901

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (1)

• 1991
  • 1991-02-14 SE SE9100450A patent/SE9100450L/sv not_active IP Right Cessation
  • 1991-10-17 EP EP91920720A patent/EP0571388B1/en not_active Expired - Lifetime
  • 1991-10-17 WO PCT/SE1991/000700 patent/WO1992014626A1/en active IP Right Grant
  • 1991-10-17 DE DE69111083T patent/DE69111083D1/de not_active Expired - Lifetime

Patent Citations (1)

Also Published As

Similar Documents

Legal Events