GB2310030A - Fluid pressure operated valve arrangement - Google Patents

Abstract

A valve arrangement comprises a body 20 having a bore 22. The bore 22 communicates with first, second and third ports 44, 46, 48. A first fluid pressure operable valve 24 controls communication between the first and second ports 44, 46. A second fluid pressure operable valve 32 controls communication between the second and third ports 46, 48. The first and second fluid operable valves 24, 32 are controlled by respective electromagnetically actuated control valves 58, 60. Preferably port 44 is connected to an accumulator 10 of a fuel system, port 46 is connected to a distributor 12 for fuel injectors 14, and port 48 is a spill port. Valves 58, 60 are opened to dump fuel from chambers 36, 38 to spill port 48 to open valves 24, 32. Closing valves 58, 60 allows pressure to recover in chambers 36, 38 to close valves 24, 32. The operation of the valves 24, 32 is alternated to repeatedly apply and dump fluid pressure to/from port 46.

Description

VALVE ARRANGEMENT This invention relates to a valve arrangement, and in particular relates to a three-way valve arrangement suitable for use in controlling the supply of fuel to an injector of an internal combustion engine.

An accumulator type fuel supply system comprises an accumulator arranged to be charged with fuel by a suitable high pressure fuel pump to maintain the pressure of fuel within the accumulator at a high level, in use. The accumulator is connected to a three-way valve, an outlet of which is connected to a distributor for distributing fuel from the accumulator to the fuel pressure actuable injectors of an associated engine in turn, in use. A second outlet of the valve is connected to a drain or spill arrangement. In use, in order to terminate injection, the injector is connected to the drain or spill arrangement in order to reduce the pressure of the fuel applied to the injector.

In an alternative arrangement, a supply line is arranged to be supplied with high pressure fuel, one or more injectors being arranged to receive fuel from the supply line through respective three-way valves. Operation of such an arrangement is similar to operation of the accumulator type arrangement, the three-way valves controlling both the timing and distribution of fuel to the injectors.

Existing designs of three-way valves restrict the flow of fuel therethrough and also have relatively slow switching speeds. Some designs further suffer from the disadvantage that, in use, on switching the valve between a position in which communication between the accumulator or other source of high pressure fuel and the distributor is permitted and a position in which communication between the distributor and the spill or drain arrangement is permitted, a position is reached at which fuel can escape from the high pressure source directly to the spill or drain arrangement. This results in a loss of high pressure fuel from the source.

It is an object of the invention to provide a valve arrangement in which the disadvantages described hereinbefore are reduced.

According to the present invention there is provided a valve arrangement comprising a body, a first fluid pressure operable valve arranged to control the flow of fluid between first and second ports of the body, a second fluid pressure operable valve arranged to control the flow of fluid between the second port and a third port of the body, and first and second control valves arranged to control the operation of the first and second fluid pressure operable valves.

The invention will further be described, by way of example, with reference to the accompanying drawing which is a diagrammatic cross sectional view of a three way valve in accordance with an embodiment of the invention.

The three way valve illustrated in the accompanying drawing comprises a body 20 having a passage 22 extending therethrough. The passage 22 includes a first, left hand, region as illustrated in the accompanying drawing, within which a first valve member 24 is slidable. The first region opens into a first annular gallery 26 which defines a seating with which the first valve member 24 is engageable. The part of the first valve member 24 within the first gallery 26 is of reduced diameter, thus a surface 25 is defined on the first valve member 24 against which high pressure fuel within the gallery 26 can act to move the valve member 24 away from its seating. Fuel can also act against the part of the conical end of the first valve member 24 located within the first gallery 26 to assist such movement.

A second, central region 28 of the passage 22 extends from the first gallery 26, the central region 28 opening into a second annular gallery 30 which in turn is connected to a third region within which a second valve member 32 is slidable. The second valve member 32 is engageable with a seating defined by the second gallery 30.

The ends of the passage 22 are closed by end plates 34 which are bolted to the body, the end plates 34 defining, together with the passage 22 and the first and second valve members 24, 32, first and second pressure chambers 36, 38. Respective springs 40, 42 are located within the first and second pressure chambers 36, 38 to bias the first and second valve members 24, 32 into engagement with their respective seatings.

A fuel supply port or line 44 communicates with the first gallery 26, the supply line 44 being connected, in use, with an accumulator 10 of a fuel system. A delivery port or line 46 is connected to the second region 28 of the passage 22, and is arranged to be connected, in use, to a distributor arrangement 12 for controlling the distribution of fuel to the injectors 14 of an associated engine, in turn. A spill line 48 is connected to the second gallery 30. The spill port or line 48 is intended to be connected to a conventional spill arrangement 16, in use. It will be recognised that when the first and second valve members 24, 32 engage their respective seatings, fuel flow between the supply line 44, delivery line 46 and spill line 48 is prevented.

The body 20 is provided with a through passage 50 which communicates with the supply line 44. The ends of the passage 50 are of enlarged diameter and receive, in screw threaded engagement, respective orifice members 52 arranged to restrict the flow of fuel from the passage 50. Each of the end plates 34 is provided with a recess 54 permitting fuel from the passage 50 to flow through the orifice members 52 to the pressure chambers 36, 38.

The first pressure chamber 36 communicates through a passage 56 with a first, solenoid actuated control valve 58 which is arranged to control communication between the first pressure chamber 36 and the spill line 48. A similar, second solenoid actuated control valve 60 controls communication between the second pressure chamber 38 and the spill line 48. The first and second control valves 58, 60 are substantially identical to one another so only the first control valve 58 will be described in detail.

The first control valve 58 is located within a cylindrical recess provided in the body, the passage 56 communicating with the base of the recess.

A generally cylindrical seating member 62 is located within the recess, the seating member 62 including a bore 64 permitting the flow of fuel therethrough. The seating member 62 abuts a valve body member 66 the lower surface of which is provided with a recess which, together with the seating member 62, defines a chamber 68 with which the bore 64 communicates. The valve body member 66 includes a central bore within which a tubular valve member 70 is slidable, an end of the valve member 70 being sealingly engageable with the seating member 62 such that when the valve member 70 engages the seating member 62, fuel flow through the valve member 70 is not permitted, such fuel flow being permitted when the valve member 70 is lifted from the seating member 62.

The valve member 70 is provided with an armature 72 which is movable to lift the valve member 70 from the seating member 62 under the influence of a solenoid actuator arrangement 74, a spring 76 being provided to bias the valve member 70 into engagement with the seating member 62. As illustrated, the upper end of the valve member 70 is closed, through passages being provided in the valve member 70 to permit fuel from the interior thereof to escape into the chamber 78, a passage 80 provided in the valve body member 66, and a further passage 82 provided in the body 20 permitting fuel to flow to the spill line 48.

With the valve arrangement in the position illustrated in the accompanying drawing, each of the valve members 24, 32 is in engagement with its respective seating thus high pressure fuel is present in the first annular gallery 26 and in the first and second pressure chambers 36, 38, the presence of the spring 40 and high pressure fuel in the first pressure chamber 36 ensuring that the first valve member 24 is maintained in engagement with its seating, and as the distributor 12 is not in communication with either the accumulator 10 or the spill arrangement 16, neither injection nor spill is occurring.

In order to commence injection, the solenoid actuator 74 of the first control valve 58 is energised to lift the valve member 70 thereof from its seating. Such movement permits fuel to flow from the first pressure chamber 36 through the first control valve 58 to the spill line 48. As the supply of fuel to the first pressure chamber 36 is restricted by the orifice member 52, the fuel pressure within the first pressure chamber 36 falls.

The reduction in fuel pressure within the first pressure chamber 36 results in a condition being reached beyond which the pressure acting on the parts of the first valve member 24 within the first annular gallery 26 is sufficient to separate the first valve member 24 from its seating, thus permitting a substantially unrestricted flow of fuel to the second region 28 of the passage 22 and then to the delivery line 46 and to the injector 14 determined by the distributor 12.

Whilst injection is taking place, the application of high pressure fuel to the second pressure chamber 38 together with the action of the spring 42 is sufficient to maintain the second valve member 32 in engagement with its seating, thus the flow of fuel to the spill line 48 is restricted to that flowing through the first control valve 58.

When injection is to be terminated, the first control valve 58 is deenergized and the valve member 70 moves into engagement with the seating member 62 under the action of the spring 76. The flow of fuel from the first pressure chamber 36 is thus terminated, the continued flow of fuel into the first pressure chamber 36 through the orifice member 52 resulting in the pressure within the first pressure chamber 36 increasing.

Such increased pressure together with the action of the spring 40 subsequently causes the first valve member 24 to move into engagement with its seating.

Following movement of the first valve member 24 into engagement with its seating, the second control valve 60 is energized thus permitting fuel to flow from the second pressure chamber 38 to the spill line 48. Due to the presence of the orifice member 52, fuel flow into the second pressure chamber 38 is restricted, thus the flow of fuel from the second pressure chamber 38 results in the pressure therein falling. The reduction in pressure subsequently permits the fuel pressure within the central region 28 of the passage 22 acting on the end of the second valve member 32 to lift the second valve member 32 away from its seating against the action of the spring 42, hence permitting fuel from the central region 28, the delivery line 46 and the lines connecting the valve arrangement to the distributor 12 and the selected injector 14 to flow to the spill arrangement 16. Such fuel flow results in the pressure of fuel at the injector 14 falling, and hence in the injector 14 closing.

After termination of injection, the second control valve 60 is deenergized, the valve member thereof moving under the action to the spring to break the communication between the second pressure chamber 38 and the spill line 48. The continued flow of fuel to the second pressure chamber 38 through the orifice member 52 results in the pressure therein increasing, and subsequently in the second valve member 32 being returned to the position illustrated in the drawing.

It will be understood that as the first and second valves 24, 32 are controlled independently of one another, the valve arrangement can be operated so as to minimise the quantity of fuel flowing to the spill line 48, thus the efficiency of the fuel supply system can be improved. The maximum lift of each of the first and second valves 24, 32 is relatively large, and hence the restriction to fuel flow therethrough when open is minimised. The control valves 58, 60 are of relatively low inertia and so opening and closing movement is relatively fast, and may be suitable for use in a fuel supply system of the type in which, during each injection cycle, each injector is opened for a short time to permit an initial pilot injection of fuel, and is subsequently closed and reopened for a main injection.

It will be recognised that other types of solenoid actuated valve than that described hereinbefore could be used for the first and second control valves 58, 60, and that the invention should not be limited to the type described hereinbefore.

Although the three-way valve described hereinbefore is used in an accumulator type system including a distributor, the valve arrangement is also suitable for use in a system of the type in which the valve controls both the timing and distribution of fuel to the injectors.

Claims (4)

1. A valve arrangement comprising a body, a first fluid pressure operable valve arranged to control the flow of fluid between first and second ports of the body, a second fluid pressure operable valve arranged to control the flow of fluid between the second port and a third port of the body, and first and second control valves arranged to control the operation of the first and second fluid pressure operable valves.

2. A valve arrangement as claimed in Claim 1, wherein the third port is connected, in use, to a spill arrangement, the first and second control valves controlling communication between the third port and first and second pressure chambers associated with the first and second fluid pressure operable valves, respectively.

3. A valve arrangement as claimed in Claim 1 or Claim 2, wherein the first and second control valves are electromagnetically actuable valves.

4. A valve arrangement substantially as hereinbefore described with reference to the accompanying drawing.