JP6203389B2 - High pressure pump - Google Patents

Description

  The present invention relates to a high pressure fuel pump operated by a cam follower lubricated with oil.

  In the high-pressure fuel pump, the plunger extends from an upper end portion that forms a piston inside the pump head to a lower end portion that includes a cam follower and a pin bush roller. The cam followers follow the cam whose rotation actuates the plunger, so that the pistons move relative to each other within the pump head. A coil spring that is compressed between the cam follower and the pump head maintains a permanent contact between the roller and the cam.

  The piston is wetted by the fuel, while the lower end and cam follower are lubricated by the engine oil, and some small amount of oil and fuel is lost as the plunger slides (or slides) in the pump head. Mix and produce undesirable turbidity.

  EP2317120 disclosed an assembly with a double lip seal to avoid mixing oil and fuel.

  Another problem involves the assembly process. Before the pump unit was fixed to the engine, the plunger was not held in the pump, and therefore the plunger sometimes dropped from the pump head in the assembly line.

  Accordingly, an object of the present invention is to provide a pump head, a cam follower cooperating with a rotating cam, a plunger extending from the pump head to the cam follower along the longitudinal axis, and the pump head and the cam follower. And a high-pressure fuel pump unit comprising a spring that is compressed by the step of urging the cam follower toward the cam. The plunger extends from a first end slidably or slidably disposed within a pump hole of a pump head to which fuel is pumped to a second end cooperating with an oil lubricated cam follower. Extend. The pump unit further includes an annular sealing member disposed around the plunger and fixed to the pump head to prevent fuel from mixing with oil.

  The sealing member is a double lip sealing member, the two lips cooperating with the plunger.

  In addition, the sealing member can be held by an inwardly directed radial force sufficient to hold the plunger in the pump head and prevent the plunger from accidentally falling off the pump head during assembly of the pump unit. The plunger can be biased.

  The sealing member is disposed in a sealing member holding sleeve attached to the pump head.

  The pump hole opens outside the pump head in the cylindrical recess, and the sealing member is disposed in the cylindrical recess.

  In another embodiment, the pump unit includes a bell-shaped member that is secured to the pump head at a location surrounding the cylindrical recess and extends axially to a distal end having an opening through which the plunger extends.

  The plunger can have an annular groove at a position permanently within the bell-shaped member. This groove accommodates the annular retaining clip, and the outer diameter of the annular retaining clip is larger than the diameter of the opening to prevent the plunger from accidentally falling out of the pump hole during assembly of the pump unit.

  The present invention will now be described by way of non-limiting illustration with reference to the accompanying drawings.

FIG. 3 is an axial sectional view of a pump unit according to the present invention. FIG. 2 is a detailed view of a part of FIG. 1. FIG. 4 is a diagram of another embodiment of a pump unit according to the present invention.

  For purposes of clarity and brevity and to facilitate understanding of this description, a bottom-up orientation as illustrated in FIG. 1 is used. Terms such as top, bottom, upper, lower,..., And downward, downward, upward, upward ( The direction "upwardly) can be used without any intent to limit for the scope of the invention, in particular with regard to the many possibilities of installing the pump in a vehicle.

  The high-pressure fuel pump 10 extends along the longitudinal axis A. The high-pressure fuel pump 10 includes a pump head 12 that is directly fixed to an engine (not shown). Alternatively, the pump head 12 may be fixed to an individual housing. The head 12 is provided with an axial hole 14. The upper end of the axial bore 14 is a pressurized chamber that receives fuel from an inlet controlled by a valve. Pressurized fuel exits the pressurization chamber through an outlet controlled by another valve. The pump head 12 is further provided with a cylindrical member 16 extending downward in the axial direction. The hole 14 extends in the center of the cylindrical member 16.

  A plunger 18 is slidably (or slidable) disposed in the hole 14. The upper end portion of the plunger 18 is a piston. The radial gap C between the hole 14 and the plunger 18 is typically a few microns, allowing the plunger 18 to slide (slid) within the hole 14 at one end, The plunger 18 can pressurize the fuel while minimizing fuel leakage from the radial gap C at the end. The plunger 18 extends downward to the lower end portion 22, and the lower end portion 22 contacts the cam follower 24. The cam follower 24 includes a cup-shaped member 26 and a pin bush roller 28 that rotates (rolls) on the rotating cam. The coil spring 30 is disposed around the plunger 18 and is compressed between the pump head 12 and the cam follower 24. More specifically, as can be seen in FIG. 1, the top of the spring 30 engages around the cylindrical member 16 and the last helix abuts the flat surface of the head 12. The lower part of the spring 30 is received by a spring seat 32 disposed inside the cup-shaped member 26.

  In the first embodiment shown in FIG. 1 and shown in detail in FIG. 2, the pump unit 10 further comprises a sealing member 34 disposed within the sealing member holding sleeve 36. The sealing member holding sleeve 36 includes a cylindrical wall 38 that is engaged and fixed to the lower end portion of the cylindrical member 16 so as to be covered by crimping, screwing, bonding, or any other means, and a central opening 42. A disk-shaped bottom wall 40. In a predetermined position, the plunger 18 extends out of the cylindrical member 16 through the opening 42. The sealing member 34 is disposed in an internal tubular space defined between the cylindrical wall 38, the bottom wall 40, and the plunger 18.

  As is known in the art, once the unit pump 10 is in place, the plunger 18 is actuated by the displacement of the cam follower 24 that rotates (rolls) on the rotating cam and moves up and down. Reciprocate. The piston is wetted by fuel while the cam follower is lubricated by engine oil. The first function of the sealing member 34 is to ensure complete separation between these two liquids by creating a barrier around the plunger 16. To ensure this, the sealing member 34 is a double lip sealing member 34 that contacts the periphery of the plunger 18 in two parallel regions.

  The second function of the sealing member 34 relates to an assembly process, particularly an assembly process when the pump unit is directly assembled to the engine. The pump unit 10 is assembled by inserting the plunger 18 into the hole 14. When finally fixed to the engine, the unity (connectivity) of the pump unit 10 is maintained. The pump head 12 is fixed to the engine, and on the opposite side, the cam follower 24 abuts the rotating cam, and the spring 30 is compressed between them to eliminate play. Prior to such assembly into the engine, the plunger 18 may fall off the pump head 12 by mistake. The second function of the sealing member 34 is to hold the plunger 18 in place and avoid such an accident. Accordingly, the sealing member 34 is further designed to apply an inward radial force from the periphery to the plunger 18. This force is sufficient to hold the plunger 18 in place after the plunger 18 is locked in the hole 14.

  In the assembly process, the sealing member holding sleeve 36 is fixed to the pump head 12, and then the sealing member 34 is disposed inside the sealing member holding sleeve 36. Thereafter, the plunger 18 passes through the sealing member 34 and is inserted into the hole 14. Alternatively, if the securing process allows, the sealing member 34 may be disposed within the sealing member retaining sleeve 36 before the sealing member retaining sleeve 36 is secured to the pump head 12.

  Next, a second embodiment will be described with reference to FIG. The cylindrical member is considerably shorter than that of the first embodiment. The short cylindrical member 44 is provided with an internal axial recess 46. There, a hole 14 is opened and a sealing member 34 is arranged. Externally, the short columnar member 44 is provided with attachment means such as a screw thread as shown in FIG. 3, or a crimped shape, adhesive surface, radial screw holes for receiving radially oriented screws. Yes. The pump head 12 is further provided with a bell-shaped member 48 attached through attachment means complementary to the means including the head 12. Internally, the bell-shaped member 48 has a cylindrical hole 50 and its diameter D1 is smaller than the outer diameter D2 of the sealing member 34. Therefore, when the bell-shaped member 48 is fixed, the inner portion of its wall is pumped. A stopper is formed that contacts the head 12 and prevents the sealing member 34 from coming off during operation. As shown in FIG. 3, the bell-shaped member 48 is provided with an opening 52 in the axial direction, the diameter D3 of which is smaller than the diameter D1 of the cylindrical hole 50, and when assembled, the plunger 18 , Exits the hole 14, penetrates the sealing member 34 and the cylindrical hole 50, and extends out through the opening 52.

  Also in this second alternative example, the sealing member 34 ensures two functions of sealing and holding of the plunger.

  In order to make the holding function more robust, the plunger 18 may have further holding means, i.e. a holding clip 54 having an outer diameter D4 which is larger than the diameter D3 of the opening 52. The clip 54 is disposed in a groove provided in the plunger 18 at a position close to the sealing member 34 when the plunger 18 is completely inserted into the hole 14. The bell-shaped member 48 is sufficiently long so that the clip 54 moves from the vicinity of the sealing member 34 to the vicinity of the opening 52 and stops in the cylindrical hole 50 when the plunger 18 moves downward. It is necessary to have. In the assembly process, if the sealing member 34 does not sufficiently hold the plunger 18, the plunger 18 slides (slids) until the clip 54 contacts the bottom wall of the bell-shaped member 48. And complete separation and undesired dropout of the plunger 18 is prevented. Also, the outer surface 56 of the bell-shaped member 48 is slightly conical with an apex towards the cam to facilitate engagement and positioning of the spring 30.

Claims (4)

A high pressure fuel pump unit (10) comprising:
A pump head (12);
A cam follower (24) cooperating with the rotating cam;
The cam follower lubricated by oil from a first end slidably disposed in the pump hole (14) of the pump head (12) along which the fuel is pumped along the longitudinal axis (A) A plunger (18) extending to a second end (22) cooperating with the child (24);
A spring (30) compressed between the pump head (12) and the cam follower (24) and biasing the cam follower (24) toward the cam;
The high-pressure fuel pump unit (10) further includes an annular sealing member (around the plunger (18) and fixed to the pump head (12) to prevent mixing of fuel with oil. 34), the sealing member (34) being a double lip sealing member (34), the two lips cooperating with the plunger (18),
The sealing with an inward radial force from the surroundings sufficient to prevent the plunger (18) from accidentally falling off the pump head (12) during assembly of the pump unit (10). The member (34) biases the plunger (18) ,
The pump hole (14) opens outside the pump head (12) in a cylindrical recess (46), and the sealing member (34) is disposed in the cylindrical recess (46).
The high-pressure fuel pump unit (10) further includes a bell-shaped member (48),
The bell-shaped member (48) is fixed to the pump head (12) at a position surrounding the cylindrical recess (46),
In addition, the bell-shaped member (48) extends in the axial direction to a terminal portion having an opening (52) through which the plunger (18) passes . A pump unit (10) according to claim 1,
The pump unit (10), wherein the sealing member (34) is disposed in a sealing member holding sleeve (36) attached to the pump head (12). A pump unit (10) according to claim 1 ,
The plunger (18) is provided with an annular groove at a position permanently in the bell-shaped member (48), and the groove accommodates an annular holding clip (54). The outer diameter (D4) of (54) is the diameter of the opening (52) to prevent the plunger (18) from accidentally falling out of the pump hole (14) during assembly of the pump unit (10). Pump unit (10) characterized in that it is larger than (D3). A pump unit (10) according to any one of claims 1 to 3,
The bell-shaped member (48) has a cylindrical hole (50) therein, and its diameter (D1) is smaller than the outer diameter (D2) of the sealing member (34). 48) is fixed, the inner part of the wall contacts the pump head (12) and a stopper is formed to prevent the sealing member (34) from being removed during operation,
The diameter (D3) of the opening (52) of the bell-shaped member (48) is smaller than the diameter (D1) of the cylindrical hole (50), and when assembled, the plunger (18) 14) A pump unit (10) characterized in that it goes out of (14), passes through said sealing member (34) and said cylindrical hole (50) and extends out through an opening (52).

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