GB2202034A

GB2202034A - Valve assembly for a gas trap

Info

Publication number: GB2202034A
Application number: GB08804258A
Authority: GB
Inventors: Mechtilde Schmid
Original assignee: Mannesmann Kienzle GmbH
Current assignee: Digital Kienzle Computersysteme GmbH and Co KG
Priority date: 1987-03-06
Filing date: 1988-02-24
Publication date: 1988-09-14
Also published as: DE3707271C1; GB8804258D0; FR2611812A1; SU1575949A3

Abstract

A valve assembly for a gas trap, required for an operating system of a diesel engine, especially in conjunction with measurement of fuel consumption, allows the separated gas to escape directly into the atmosphere under normal operating conditions (Fig. 3) but, in an inclined position of the automobile (Fig. 5) or under faulty functioning of the float-controlled valve situated in the gas trap (Fig. 4) prevents escape of fuel. In a valve chamber (31), a ball (36) of high density and a valve bail (37) able to float on diesel oil, are disposed. The geometry of the valve chamber (31) and the diameters of the balls (36 and 37) are so chosen that the ball (36), in an inclined position of the automobile and therefore of the gas trap and valve chamber, rolls along chamber wall (32) and presses the valve ball (37) into the valve seating (33) to close outlet (35), which is formed in a threaded insert (34, Fig. 2) which can be fitted to the gas trap (13, Fig. 2). In the normal orientation, if the fuel level in the tank of the gas trap is too high, the valve ball (37) floats on the oil and closes outlet (35) (Fig. 4). <IMAGE>

Description

TITLE: Valve assembly for a gas trap This invention relates to a valve assembly for a gas trap, in which trap a valve controlled by a float is disposed and the tank of which serves, in an operating system of a diesel engine equipped with means for measuring the fuel consumption, for receiving the excess quantity of fuel flowing back from the injection pump, wherein, in a valve chamber equipped with the gas outlet opening, a seating associated with the gas outlet opening for a valve ball is formed.

The operating system of a diesel engine provides that considerably more fuel is circulated by the fuel pump than is consumed by the injection pump. The relatively large excess quantity of fuel, generally flowing back to the fuel storage tank, serves for cooling and also has a scavenging function in respect of accumulations of gas bubbles in the injection pump.

If, in an operating system of this class, the fuel consumption is to be measured, then it is usual to feed back the excess quantity of fuel into the suction line between the fuel pump and the fuel storage tank and to incorporate the flow measuring device into the suction line between the feed-in point and the fuel tank.

Such a fuel circuit has the consequence that, on the one hand the circulating fuel is considerably heated up and thus the cooling function for the injection pump 19 lost, and on the other hand degassing of the excess quantity of fuel in the fuel tank can no longer take place. In Cummins engines, and also in distributor injection pumps and diaphragm feed pumps, the gas enrichment in the fuel reflux ~\ stream is particularly high, so that in these systems at least it is unavoidable to provide an additional tank for gas separation.It then becomes convenient, for the feeding of the excess quantity of fuel into the suction line, to pass the suction line through the base of this gas trap or separator and to provide, between the tank chamber and the relevant duct in the base of the gas trap associated with the suction line, a valve which is controlled by a float mounted in the gas trap.

The requirement for keeping the expense for such an auxiliary device, especially its overall volume, as low as possible, and on the other hand the fact that the fuel flozz-back often takes place in surges and due to a fraction of up to 15:r; of gas sometimes occurs in a foam phase, while at the same time the escape of fuel when the tank is tilted or the vehicle is capsized must be avoided, means that the gas escape cannot take place directly into the open air, but that the gas trap must be connected with the fuel storage tank via a gas line. The gas line may, without additional expense, be connected with the tank opening provided for the fuel flow-back during operation without measurement of fuel consumption.

As already mentioned, in the chosen operating system the circulating fuel heats up considerably, so that in the majority of cases a cooling assembly must be provided which, if it is to achieve optimum effect, comprises a cooling circuit between a heat exchanger and the fuel tank, this circuit being independent in respect of flow of the fuel circuit and being supplied by a separate pump. The free tank opening is occupied by this cooling circuit in the chosen operating system, so that an additional bore must be provided at the fuel tank for the intended gas line, which, apart from the expense, gives rise to authorization problems.

In order to overcome this problem, it would be conceivable to connect the gas line with the return line of the cooling circuit, but this would lead, without a non-return valve in the gas line, to faulty measurements. A liquid-tight non-return valve of this class would, however, cause an excess pressure in the gas trap, which would greatly adversely affect the affect the functioning of the gas trap, i.e. the degassing, and that of the float-controlled feed valve, i.e. a pressure-free feed of the flowing-back fuel into the suction line.

The objective underlying the present invention therefore was to create a valve assembly which, while avoiding the stated problems, on the one hand permits degassing without feed-back problems, and on the other hand prevents escape of fuel from the gas trap.

The solution to this objective provides that the valve ball is freely movable in the valve chamber, that a likewise freely movable rolling object of high density is associated with the valve ball, and that a depression associated with the rolling object is formed in the valve chamber opposite to the valve seating in such a manner that the rolling object, at a specific inclination of the tank axis to the vertical, rolls along the wall of the depression and presses the valve ball into the valve seating.

A preferred form of embodiment is characterized in that the density of the valve ball is less than the density of diesel oil.

The solution found has, apart from the fact that the stated objective is completely achieved, the advantage that it does not necessitate any additional installation expense during fitting of the individual components of the fuel consumption measuring system, that it can be realized at relatively low expense and that it can be integrated into the gas trap.

The invention will be explained in greater detail below by reference to the attached drawings. The Figures in the drawings show: Fig. 1 a schematic illustration of an operating system designed for measuring fuel consumption of a diesel engine with cooling circuit and gas separation, Pig. 2 a partial view of a gas trap according to detail A in Fig. 1 with a section through the valve assembly according to this invention, Fig. 3 an operating sketch showing the normal functioning of the gas trap, Fig. 4 an operating sketch in the normal orientation of the gas trap and with the fuel level excessively high, Fig. 5 an operating sketch in a tilted orientation of the gas trap, Fig. 6 a sectional view of a variant of construction of the valve assembly.

The schematic representatiqn of Fig. 1 shows an operating system for a diesel engine having a fuel storage tank 1, a suction line 2 leading from the fuel tank 1 and into which a prefilter 3, a flow measuring device 4 having a lead-sealed bypass 5 which can be actuated in fault cases in parallel with it, and a non-return valve 6 are incorporated.

The suction line 2 is connected with a fuel circuit 7, in which a specific excess quantity of fuel, usually relatively large compared with the "consumed" injected quantity, is kept in circulation, starting from a fuel pump 8 via a main filter 9, the injection pump 10 (the injection nozzles are referenced 11), a non-return valve 12 and a gas trap 13. Reference 14 denotes a heat exchanger, through which on the one hand the fuel circuit 7 and on the other hand a cooling circuit 16, operated by a feed pump 15 and fed from the fuel tank, are conducted.

A preferred form of construction of the gas trap 13, which comprises basically a tank, is composed of a lid 17, a preferably cylindrical sleeve 18 and a base, not illustrated in Fig. 2, which are all connected together by suitable screwed con:lections with the intermediary of seals, of which one is referenced 19. Reference 20 in Fig. 2 denotes a float, which serves for controlling the valve disposed in the base, which is associated with a duct formed in the base and communicating with the suction line 2. Since the construction of the gas trap 13 in this region is not of importance to the present invention, it has not been illustrated. Reference can be made, however, to DE-OS 35 12 191, in which a gas trap of this type is described.

The hose attachment 21 fixe#d to the lid 17 serves for connecting of the flow-back branch of the fuel circuit 7 coming from the injection pump 10. The gas-charged fuel strikes a baffle dome 22, a keel 23 formed on the baffle dome 22 preventing splashing and thus additional absorption of gas and simultaneously causing substantial distribution of the fuel over the baffle dome 22. The fuel flowing off the baffle dome 22 first flows downwards in the annular space 24 between the outer sleeve 18 and the inner sleeve 25, then rises again in a further annular chamber, not shown, in order to overflow into an inner chamber 26, in which the float 20 is situated. By this extended flow path and the large-area distribution on the baffle dome 22, optimum degassing is achieved.Reference 27 denotes a stub pipe integrally formed on the baffle dome 22, through the opening 28 of which the gas entering the chamber 26 escapes into the free space 29 provided in the lid 17.

The free space 29 is, as Flg. 2 also shows, connected by n bore 30 with the valve chamber 31 of the valve assembly according to the present invention. 'lNle valve chamber 31 is formed on the one hand of a depression 32, conical in the preferred form of embodiment, and on the other hand of an also conical depression 33, which is provided in a threaded insert 34, which can be connected with the lid 17, and leads out into an opening 35 which, advantapeously equipped with a suitable dust protector, serves for gas escape to atmosphere.In the valve chamber 31 there is a first ball 36 of high density (in this connection other forms of rolling object and other forms of depression would also be conceivable if functioning in every direction were dispensed with) and a further valve ball 37, formed as a hollow ball, the density of which is less than the density of diesel oil.

Both the balls 36 and 37 are freely movable in the valve chamber 31; the depression 33 serves as valve seating for the valve ball 37 and the ball 36 is, in the normal orientation of the gas trap 13, i.e.

in the required installation position, held by gravity in the depression 32.

Whereas, in the operating sketch of Fig. 3, a further enlarged representation of the valve assembly in the normal functioning of the gas trap 13 is shown - the arrow S shows the direction of gravity in the operating sketch of Fig. 4 a situation is illustrated, in which an overshoot of the fuel level in the tank of the gas trap 13, in the normal orientation of this tank, takes place. The valve ball 37 has floated up on the diesel oil entering the valve chamber 31 and closes the valve. In contrast to this, the operating sketch of Fig. 5 shows the tilted orientation of the gas trap 13. Here the ball 36 has rolled along the wall of the depression 32 into a stable position, in which on the one hand it is still at a certain distance a from the wall of the depression 33 and on the other hand it presses the valve ball 37 under the effect of gravity into the valve seating in the depression 33.

Fig. 6 shows a variant of construction, in which the form of the valve chamber 31 has been modified, in particular the depression 32 has å different angle and the conical valve seating is formed in a component 38 which has been pressed into the lid 17.

The diameters of the balls 36 and 37 are, of course, also variable to suit the contours of the valve chamber or they must be varied to suit the desired response inclination. The decisive feature is that the two balls, when the tank axis tilts, act so to speak as'a wedge gear or, to look at it another way, in the closed position of the valve assembly a blocking function is obtained in such a manner that the ball of higher density 36, under the action of gravity S, bears on the one hand against the wall of the depression 32 and on the other hand against the valve ball 37.

Claims

CLAIMS:

1. Valve assembly for a gas trap, in which trap a valve controlled by a float is disposed and the ta * of which serves, in an operating system of a diesel engine equipped with means for measuring the fuel consumption, for receiving the excess quantity of fuel flowing back from the injection pump, wherein, in a valve chamber equipped with the gas outlet opening, a seating for a valve ball associated with the gas outlet opening is formed, characterized in. that the valve ball (37) is freely movable in the valve chamber (31), that an also freely movable rolling object of high density is associated with the valve ball (37), and that a depression associated with the rolling object is formed in the valve chamber (31) opposite to the valve seating in such a manner that the rolling object, at a specific incli nation of the tank axis to the vertical, rolls along the wall of the depression and presses the valve ball (37) into the valve seating.

2. Valve assembly according to Claim 1, characterized in that the density of the valve ball (37) is less than the density of diesel oil.

3. Valve assembly according to Claim 2, characterized in that the valve ball (37) is formed as a hollow ball.

4. Valve assembly according to Claim 1, characterized in that the rolling object is formed as a ball (36) and the depression (32) associated with the rolling object is of conical shape.

5. Valve assembly according to Claim 1, characterized in that the depression (32) is formed in the id (17) of the gas trap (13) and that the valve seating and the gas outlet opening (35) are formed in a threaded insert (34) capable of being connected with the lid (17) and of being axially associated with the depression (32).

6. Valve assembly substantially as described with reference to Figure 1, Figure 2 or Figure 6 of the accompanying drawings.