FR2490733A2 - Heated fuel feed for diesel engine - has thermostatic flow valve incorporated in filter to save space - Google Patents

Abstract

The fuel pump draws fuel from a filter with an inlet from the tank into a space inside the filter lid. Excess fuel from the pump enters a channel at the top of the lid from which there is a non return valve back to the tank and a second non return valve into the incoming fuel space. The flow through the second valve is controlled by a disc with an opening which is moved to vary the free cross section of the non return valve. The disc is turned by a bimetal coil immersed in the oil flowing into the filter.

Description

 The invention relates to a device for reheating gas oil serving as fuel for diesel engines, the fuel coming from the tank of a vehicle passing successively through a filter and then through a high pressure pump delivering a supply flow rate to the injectors and a flow rate excess said sweep flow and normally brought back to the vehicle tank, device in which an additional pipe is connected to the return flow sweep pipe and opens into the pipe connecting the tank to the filter via a thermostatic valve allowing recycling by the filter of all or part of the sweeping flow rate according to main patent application N 79-11633 of May 8, 1979.

 This system certainly works satisfactorily but it sometimes happens that the potential user is somewhat put off by the introduction of an additional member in an already fairly congested space.

 The object of the present invention is to remedy this drawback by proposing a compact device, not very large and easy to assemble while having absolutely the same efficiency as the device described in the main patent.

 To this end, the invention relates to a device for reheating gas oil serving as fuel for diesel engines, the fuel coming from the tank of a vehicle passing successively through a filter and then through a high pressure pump delivering a supply flow rate to the injectors. and an excess flow called sweep flow and normally returned to the vehicle tank, device in which an additional pipe is connected to the return flow sweep line and opens into the pipe connecting the tank to the filter via a thermostatic valve authorizing the recycling by the filter of all or part of the sweeping flow according to main patent application N079-11633 of May 8, 1979, characterized in that the various members constituting the thermostatic valve are housed in a block integral with the filter. The thermostatic filter-valve assembly is hardly more bulky than the filter alone. It finds its place in the same place as a conventional filter and its connection is very easy.

The invention will be better understood using the attached drawing in which
- Figure 1 is a vertical sectional view of
the following thermostatic filter-valve assembly
the invention, and
- Figure 2 is a schematic view of the means of
circulation of diesel including all
filter-valve according to the invention.

The housing 1 of the thermostatic filter-valve assembly according to the invention contains a filter cartridge 2
It is surmounted by a block 3 in which is housed, inter alia, a thermostatic valve constituted by a bimetal spiral spring 4 and a disc 5 perforated by a passage 6. The spring 4 is fixed at one of its ends on the pivot 7
On the other end of the spring 4 is welded a lug 8 forcibly engaged in a hole made in the disc 5. The disc 5 is mounted so as to be able to rotate freely around the pivot 7, its rotation being controlled only by the lug 8.

 The line 9 introduces into the chamber 10 the fuel coming from the tank 11 (FIG. 2). A passage 12 and a descending conduit 13 then allow the fuel to descend into the casing 1 to pass through the filter cartridge 2 and the support 14 of this cartridge before gaining passage 15, the line 16 and the fuel pump 17.

 In the upper face of the block 3 there is a pipe 18 which collects all of the excess flow coming from the pump 17 through the pipe 19 as well as all of the flow of fuel not consumed by the injectors and collected by the pipe 20.

 The end of the pipe 18 is flush with the end of a passage 21 formed in the block 3 and extending over a large part of the width of this block 3. The end of this passage 21 widens in one stilling chamber 22 in which the circulation speed of the recycled fuel decreases to facilitate degassing if necessary.

The plenum 22 is perforated on its underside by a passage 23 opening into a chamber 24 and on its upper face by a passage 25 opening into a chamber 26
Chamber 23 contains a non-return valve 27 pressed against the passage 23 by a spring 28. This valve is calibrated to open at a determined differential pressure
P1, which is for example 10 mbar.

The chamber 26 likewise contains a non-return valve 29 pressed against the passage 25 by a spring 30. This valve is calibrated to open at a differential pressure P2 greater than the calibration pressure P1, of the valve 27. This pressure is for example from 20 to 30 mbar As a result, when the passage 6 is axially aligned with the passage 23, the fuel leaves the chamber 22 preferably through the passage 23
The non-return valve 29 has in its center a small calibrated orifice 31 with a diameter of 0.1 to 1 mi, depending on the size of the engine, to permanently allow the degassing of fuel.

 A chamber 32 is connected to the chamber 26 which returns the recycled fuel to the tank 11.

 The circulation of fuel in the filter is countered by the position of the perforated disc 5.

For a temperature of the fuel arriving through the line 9 below 20-250C, the passage 6 is axially aligned with the passage 23, the disc 5 being at the end of its travel towards the cold temperatures. The fuel admitted in
18 then preferably crosses the passage 23 to mix with the fuel coming from the pipe 9. The latter is then heated enough to recast any paraffin crystals which clog the filter 2.

 When the temperature of the fuel coming from the tank via the line 9 is greater than 20-250C or when the heating provided by recycling is sufficient, the bimetal spring 4 begins to act and the passage 6 being displaced, the fuel recycled through the line 18 , the passage 2] and the chamber 22 is completely returned via the pipe 32 or tank 11.

Claims (1)

CLAIM 1 - Heating device for diesel fuel used as fuel  diesel engines, fuel from the tank  of a vehicle passing successively through a filter then  by a high pressure pump delivering a feed flow  tation of injectors and an excess flow called flow  sweeping and normally brought back to the vehicle tank,  device in which an additional pipe is  connected to the sweep flow return line and  opens into the line connecting the tank to the filter  through a thermostatic valve allowing  recycling by the filter of all or part of the flow of  scanning according to main patent application N079-11633  of May 8, 1979, characterized in that the various organs  constituting the thermostatic valve are housed in a  block (3) integral with the filter.