GB2126664A

GB2126664A - Delivery valve

Info

Publication number: GB2126664A
Application number: GB08321402A
Authority: GB
Inventors: Donald Worby
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1982-09-08
Filing date: 1983-08-09
Publication date: 1984-03-28
Also published as: GB8321402D0

Abstract

A delivery valve for use with a fuel injection pump includes first and second valve members 15, 23 resiliently biased into contact with seatings. The seating 17 for the first valve member is formed in a supporting body but the seating of the second valve member is defined on the first valve member. The second valve member and its seating are arranged so that the impact of the first valve member with its seating acts to urge the second valve member into contact with its seating. <IMAGE>

Description

SPECIFICATION Delivery valve This invention relates to a delivery valve for use with a fuel injection pump, the valve being located in an outlet of the pump and including a first valve member which is resiliently biased into contact with a seating and which is lifted from the seating during delivery of fuel by the pump, and a second valve member resiliently biased into contact with a seating, said second valve member being held in contact with its seating during delivery of fuel by the pump but being lifted from its seating to permit return flow of fuel from a pipeline connected to the outlet when delivery of fuel by the pump ceases.

An example of such a delivery valve is described in the specification of United States Patent 3364863 and in Figure 3 of the drawings thereof the first valve member is provided with a passage defining a seating for the second valve member. The second valve member is urged into contact with the seating by a spring acting in the direction of movement of the first valve member during delivery of fuel by the pump. This can lead to problems when the first valve member contacts its own seating when the delivery of fuel ceases.

The impact between the first valve member and its seating can unseat the second valve member from its seating leading to undesirable changes in the designed pressure unloading characteristics of the complete valve assembly. A similar construction is seen in Figure 1 of British Specification 399858 and in Figure 1 of British Specification 1 056337. In Figure 3 of British Specification 399858 there is shown a construction in which the second valve member is provided in a separate housing and is therefore unaffected by the impact of the first valve member with its seating. This form of construction however is expensive and also bulky.

The object of the present invention is to provide a delivery valve of the kind specified in an improved form.

According to the invention a delivery valve for use with a fuel injection pump, the delivery. valve being located in an outlet of the pump, comprises a first valve member, first resilient means biasing the valve member into contact with a first seating said valve member being lifted from the seating during delivery of fuel by the pump, a second valve member, second resilient means biasing the second valve member into contact with a second seating, said second valve member being held in contact with the second seating during the delivery of fuel by the pump but being lifted from the second seating to permit return flow of fuel from a pipeline connected to the outlet when delivery of fuel by the pump ceases, characterised in that said first valve member comprises a body shaped at one end for engagement with the first seating, a chamber defined in the body, a first passage connected with said chamber and communicating with said injection pump, a second passage formed in the body, said second passage being open to the other end of the body and opening into said chamber at the end thereof adjacent said one end of the body, said second seating being defined about the opening whereby the impact of the body with the first seating will act to urge the second valve member into contact with its seating.

An example of a delivery valve in accordance with the invention will now be described with reference to the accompanying drawing which shows the valve in sectional side elevation. The delivery valve generally indicated at 10, is conveniently housed within a part of the body of an injection pump 11 having an outlet 1 2 from its pumping chamber. The outlet is connected by way of the delivery valve to a pipeline 13 which in turn is connected to a fuel nozzle 14.

The delivery valve includes a cylindrical body 1 5 slidable within a bore 16 the one end of which is connected to the outlet 12 and the other end of which is connected to the pipeline 1 3. the one end of the bore defines a seating 17 with which can engage the shaped one end of the body 1 5.

The body forms the first valve member of the delivery valve and it is biased into contact with the seating 1 7 by a coiled spring 15A. It is lifted from the seating to allow fuel flow from the inlet 12 to the pipeline 1 3 along flutes or grooves 1 8, by the pressure of fuel acting on its one end.

Within the body there is defined a chamber 19 which is conveniently formed by a drilling extending towards the one end of the body and having its open end closed by a plug 20. A first passage 21 extends from the one end of the body and opens into the side wall of the chamber so that the chamber is in permanent communication with the inlet 1 2. A second passage 22 extends from the outer side wall of the body and opens into the chamber at the one end thereof. At its point of opening into the chamber the second passage 22 defines a seating for a second valve member conveniently in the form of a ball 23. The ball is urged into contact with the seating by a spring 24 located between the plug and an abutment which engages the ball. Any convenient form of valve member can be employed.

In use, during delivery of fuel by the injection pump the body 1 5 is lifted from its seating but the ball 23 is held on its seating by the spring 24 and by any pressure drop which may exist between the ends of the body. When the flow of fuel from the pump ceases the body is returned by the action of the spring 1 5A but any impact between the body and the seating will serve only to press the ball 23 harder against its seating. Flow of fuel can take place from the pipeline to the pump when the body has seated, through the aforesaid passages, the ball being lifted from its seating while such flow is taking place.

Claims

1. A delivery valve for use with a fuel injection pump, the valve being located in an outlet of the pump comprising a first valve member, first resilient means biasing the valve member into

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Delivery valve This invention relates to a delivery valve for use with a fuel injection pump, the valve being located in an outlet of the pump and including a first valve member which is resiliently biased into contact with a seating and which is lifted from the seating during delivery of fuel by the pump, and a second valve member resiliently biased into contact with a seating, said second valve member being held in contact with its seating during delivery of fuel by the pump but being lifted from its seating to permit return flow of fuel from a pipeline connected to the outlet when delivery of fuel by the pump ceases. An example of such a delivery valve is described in the specification of United States Patent 3364863 and in Figure 3 of the drawings thereof the first valve member is provided with a passage defining a seating for the second valve member. The second valve member is urged into contact with the seating by a spring acting in the direction of movement of the first valve member during delivery of fuel by the pump. This can lead to problems when the first valve member contacts its own seating when the delivery of fuel ceases. The impact between the first valve member and its seating can unseat the second valve member from its seating leading to undesirable changes in the designed pressure unloading characteristics of the complete valve assembly. A similar construction is seen in Figure 1 of British Specification 399858 and in Figure 1 of British Specification 1 056337. In Figure 3 of British Specification 399858 there is shown a construction in which the second valve member is provided in a separate housing and is therefore unaffected by the impact of the first valve member with its seating. This form of construction however is expensive and also bulky. The object of the present invention is to provide a delivery valve of the kind specified in an improved form. According to the invention a delivery valve for use with a fuel injection pump, the delivery. valve being located in an outlet of the pump, comprises a first valve member, first resilient means biasing the valve member into contact with a first seating said valve member being lifted from the seating during delivery of fuel by the pump, a second valve member, second resilient means biasing the second valve member into contact with a second seating, said second valve member being held in contact with the second seating during the delivery of fuel by the pump but being lifted from the second seating to permit return flow of fuel from a pipeline connected to the outlet when delivery of fuel by the pump ceases, characterised in that said first valve member comprises a body shaped at one end for engagement with the first seating, a chamber defined in the body, a first passage connected with said chamber and communicating with said injection pump, a second passage formed in the body, said second passage being open to the other end of the body and opening into said chamber at the end thereof adjacent said one end of the body, said second seating being defined about the opening whereby the impact of the body with the first seating will act to urge the second valve member into contact with its seating. An example of a delivery valve in accordance with the invention will now be described with reference to the accompanying drawing which shows the valve in sectional side elevation. The delivery valve generally indicated at 10, is conveniently housed within a part of the body of an injection pump 11 having an outlet 1 2 from its pumping chamber. The outlet is connected by way of the delivery valve to a pipeline 13 which in turn is connected to a fuel nozzle 14. The delivery valve includes a cylindrical body 1 5 slidable within a bore 16 the one end of which is connected to the outlet 12 and the other end of which is connected to the pipeline 1 3. the one end of the bore defines a seating 17 with which can engage the shaped one end of the body 1 5. The body forms the first valve member of the delivery valve and it is biased into contact with the seating 1 7 by a coiled spring 15A. It is lifted from the seating to allow fuel flow from the inlet 12 to the pipeline 1 3 along flutes or grooves 1 8, by the pressure of fuel acting on its one end. Within the body there is defined a chamber 19 which is conveniently formed by a drilling extending towards the one end of the body and having its open end closed by a plug 20. A first passage 21 extends from the one end of the body and opens into the side wall of the chamber so that the chamber is in permanent communication with the inlet 1 2. A second passage 22 extends from the outer side wall of the body and opens into the chamber at the one end thereof. At its point of opening into the chamber the second passage 22 defines a seating for a second valve member conveniently in the form of a ball 23. The ball is urged into contact with the seating by a spring 24 located between the plug and an abutment which engages the ball. Any convenient form of valve member can be employed. In use, during delivery of fuel by the injection pump the body 1 5 is lifted from its seating but the ball 23 is held on its seating by the spring 24 and by any pressure drop which may exist between the ends of the body. When the flow of fuel from the pump ceases the body is returned by the action of the spring 1 5A but any impact between the body and the seating will serve only to press the ball 23 harder against its seating. Flow of fuel can take place from the pipeline to the pump when the body has seated, through the aforesaid passages, the ball being lifted from its seating while such flow is taking place. Claims

1. A delivery valve for use with a fuel injection pump, the valve being located in an outlet of the pump comprising a first valve member, first resilient means biasing the valve member into contact with a first seating said valve member being lifted from the seating during delivery of fuel by the pump, a second valve member, second resilient means biasing the second valve member into contact with a second seating, said second valve member being heid in contact with the second seating during the delivery of fuel by the pump but being lifted from the second seating to permit return flow of fuel from a pipeline connected to the outlet when delivery of fuel by the pump ceases, characterised in that said first valve member comprises a body shaped at one end for engagement with the first seating, a chamber defined in the body, a first passage connected with said chamber and communicating with said injection pump, a second passage formed in the body, said second passage being open to the other end of the body and opening into said chamber at the end thereof adjacent said one end of the body, said second seating being defined about the opening whereby the impact of the body with the first seating will act to urge the second valve member into contact with its seating.

2. A delivery valve according to Claim 1 in which said body is slidable within a bore, said one seating being defined at one end of the bore, the other end of the bore in use, being connected to said pipeline.

3. A delivery valve according to Claim 1 in which said second passage is defined at least in part by a groove on the body.

4. A delivery valve for use with a fuel injection pump comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawing.