An anti-surge vessel for a motor vehicle fuel tank

Abstract: An anti-surge vessel for the fuel tank of a motor vehicle, including a hollow body (1) defining a fuel suction chamber (9) communicating with the tank through an inlet aperture (11) with which is associated a fuel recirculation duct (13). The hollow body (1) has a portion (17) which is raised with respect to the bottom of the tank which delimits, together with part of the bottom wall (3) of the hollow body (1) a flow passage with a converging cross-section, and the recirculation duct (13) has an end portion (15) between the bottom of the tank and the raised portion (17) and facing the converging cross-section flow passage.

Description: The present invention relates to an anti-surge vessel for a motor vehicle fuel tank, of the type indicated in the pre-characterising portion of appended claim 1. DE-A-2 401 728 discloses an anti-surge vessel of the type specified above. The main problem associated with prior art anti-surge vessels as described above is that it is not possible to suck up the film of fuel at the bottom of the tank owing to the thickness of the bottom wall of the body constituting the anti-surge vessel. The thickness of this wall in fact keeps the fuel suction chamber raised above the bottom of the fuel tank. The main object of the present invention is to provide an anti-surge vessel which makes it possible to suck up almost all the fuel in the tank, even when the fuel level is very low, and which therefore enables the entire volume of the tank to be used efficiently. This object is achieved by virtue of the features set forth in claim 1. Owing to these characteristics, it is possible to dispose the end portion of the recirculation duct adjacent the bottom of the fuel tank and, thanks to the converging flow passage and the ejector function performed by the end portion of the recirculation duct, to draw into the suction chamber of the hollow body even the fuel at the bottom of the tank. Further characteristics and advantages of the present invention will become apparent from reading the detailed description which follows, given with reference to the appended drawings, provided purely by way of non limitative example, in which: Figure 1 is an elevation side view of an anti-surge vessel according to the invention, and Figure 2 is a side view, partially sectioned on the line II-II of the vessel of figure 1. With reference to the drawings, an anti-surge vessel for a car fuel tank includes a hollow body, made for example of plastics material, generally indicated 1. The body 1 is substantially cylindrical and upwardly open. It has a bottom wall 3 intended to rest on the bottom of the fuel tank (not shown in the drawings). The body 1 is further provided with a spiral side wall 5 so as to delimit a substantially circular duct 7 which extends around the lateral perimeter of the body 1 and which serves to put a suction chamber 9 within the body 1 into communication with the tank, through an inlet aperture 11. Inside the chamber 9 an electrical pump (not shown) is arranged in known manner for sucking the fuel present in the chamber 9. The electrical pump delivers the fuel to the car engine and the excess fuel not used by the engine returns to the tank through a recirculation duct 13 arranged outside the hollow body 1. The duct 13 has an end portion 15 intended to be disposed parallel to and adjacent the bottom of the tank and to function as an ejector. A tab 17, normally integral with the side wall 5 of the body 1, extends radially of the wall 5 and is arranged parallel to the bottom 3, near the aperture 11. The tab 17 is raised from the bottom wall 3 and therefore, when the body 1 is resting on the bottom of the tank, it is elevated with respect to the bottom of the tank. The end portion 15 of the recirculation duct 13 is fitted between the tab 17 and the bottom of the tank, facing the aperture 11 so that a flow passage is delimited between the tab 17 and the bottom of the tank for the fuel in the tank, which flows into the duct 7 through this passage and the aperture 11. A portion of the bottom wall 3, in correspondence with the aperture 11, cooperates with the tab 17 to define the said flow passage. This portion includes an end lip 19 which extends towards the end portion 15 of the recirculation duct 13 and has a surface 21 inclined relative to the bottom 3 of the body 1 and facing the tab 17 so as to define a cross-section of the flow passage which converges towards the interior of the body 1. Preferably, the lip 19 extends at least partly under the tab 17. In use, any excess fuel conveyed to the engine is returned along the recirculation duct 13 as far as its end portion 15 where it opens into the converging duct delimited above by the tab 17 and below by the inclined surface 21 of the lip 19. The flow of recirculated fuel from the portion 15 creates a depression which draws fuel from the region at the bottom of the tank. In this way, the rate of fuel recirculation flow is exploited to draw the fuel in the tank through the flow passage into the duct 7. The converging cross-section of the flow passage accelerates the fuel entering the body 1 and therefore the fuel level in the chamber 9 is considerably higher than that in the tank, thus ensuring that the pump within the body 1 operates even with a minimal fuel level in the tank.

Claims: An anti-surge vessel for the fuel tank of a motor vehicle, including a hollow body (1) with a bottom wall (3) intended to rest on the bottom of the fuel tank, said body (1) defining a substantially isolated fuel suction chamber (9) for communicating with the tank through an inlet aperture (11) with which is associated a fuel recirculation duct (13) which operates as an ejector to draw the fuel towards the interior of the suction chamber (9) through the inlet aperture (11), wherein the hollow body (1) has near its bottom wall (3) on the outside of a side wall a portion (17) delimiting a flow passage, this portion (17) being adapted to stand raised with respect to the bottom of the fuel tank and the flow passage having a cross-section converging towards the interior of the hollow body (1), the recirculation duct (13) having an end portion (15), adapted to be substantially parallel to the bottom of the fuel tank, this end portion (15) facing said converging cross-section flow passage and wherein said inlet aperture (11) is adapted to open on to the fuel tank at the converging cross-section flow passage, characterised in that the said raised portion (17) delimits the flow passage together with part of the bottom wall (3) of the hollow body (1) having an end lip (19) extending from the bottom wall (3) towards the end portion (15) of the recirculation duct (13), fitted below the raised portion (17), this lip (19) having an inclined surface (21) sloping downwardly towards the bottom wall (3) and facing the raised portion (17), the lip (19) tapering in thickness and ending with a sharp edge intended for substantially touching the bottom wall of the tank, so that even the fuel at the bottom of the tank can be drawn into the suction chamber (9) of the hollow body (1). An anti-surge vessel according to claim 1, characterised in that the said end lip (19) extends at least in part beneath the raised portion (17). An anti-surge vessel according to claim 1 or 2, characterised in that the raised portion is a tab (17) extending to the exterior of the hollow body (1) and being substantially parallel to the bottom wall thereof (3). An anti-surge vessel according to claim 1, characterised in that the flow passage opens into a duct (7) communicating with the suction chamber (9), which duct (7) extends along the perimeter of the hollow body (1). A fuel tank for a motor vehicle including an anti-surge vessel according to any one of the preceding claims.

Inventors: BIANCO GIOVANNI, BIANCO, GIOVANNI
Applicants: BITRON SPA, BITRON S.P.A.
Application year: 1993
Main classification: B60K15
IPC codes: F02M37, B60K15