High pressure pump for a fuel injection system

Abstract

The invention relates to a high pressure pump for a fuel injection system, in particular a common rail injection system, comprising a housing part (1) with a bore (2), in which a pump piston (3) is received such that it can be moved with a reciprocating movement, which pump piston (3) is supported via a tappet assembly (4) on a cam (5) or eccentric and delimits a pump working chamber (6) in the axial direction, which pump working chamber (6) can be filled with fuel via an upstroke valve (7) which is integrated into the high pressure pump. According to the invention, a feed bore (8) is configured in the housing part (1) in order to supply the upstroke valve (7) with fuel, which feed bore (8) is connected to a bore (11) of a further housing part (12), which bore (11) connects a pump interior chamber (9) and a tappet chamber (10).

Claims

1. A high pressure pump for a fuel injection system, comprising a housing part (1) with a bore (2), in which a pump piston (3) is accommodated in such a way that the pump piston can be moved with a reciprocating motion, which pump piston (3) is supported via a tappet assembly (4) on a cam (5) or an eccentric and delimits a pump working chamber (6) in an axial direction, which pump working chamber (6) is configured to be filled with fuel via a suction valve (7), which is integrated into the high pressure pump, characterized in that a feed bore (8) is formed in the housing part (1) in order to supply the suction valve (7) with fuel, which feed bore (8) is connected to a further bore (11) of a further housing part (12), which further bore (11) connects a pump interior chamber (9) and a tappet chamber (10), wherein the cam (5) or the eccentric is located within the pump interior chamber (9), wherein the feed bore (8) is connected to the further bore (11) by a branch bore (14) formed in the further housing part (12), wherein the further bore (11) is handle-shaped, having first and second portions connected by a bend, wherein the further bore (11) is at least partly located adjacent to a flange surface (13) of the first housing part (1) and directly connects to the tappet chamber (10) at the first portion, and wherein the branch bore (14) extends between the flange surface (13) and the first portion of the handle-shaped bore (11).

2. The high pressure pump as claimed in claim 1, characterized in that the housing part (1) is flanged to the further housing part (12) via the flange surface (13), and the feed bore (8) opens into the flange surface (13).

3. The high pressure pump as claimed in claim 1, characterized in that, downstream of the connection of the feed bore (8), the bore (11) connecting the pump interior chamber (9) and the tappet chamber (10) has a free flow cross section which is reduced relative to that of the feed bore (8).

4. The high pressure pump as claimed in claim 1, characterized in that the suction valve (7) is electromagnetically controllable and has a solenoid (15) and an armature (16), which interacts with the solenoid (15).

5. The high pressure pump as claimed in claim 1, characterized in that the suction valve (7) comprises a valve body (17), which is inserted into the bore (2) in the housing part (1).

6. The high pressure pump as claimed in claim 1, characterized in that the valve body (17) has an axial bore (18), in which a valve tappet (19) is accommodated in an axially movable manner.

7. The high pressure pump as claimed in claim 1, characterized in that the valve body (17) is surrounded by an annular chamber (20), into which the feed bore (8) opens.

8. The high pressure pump as claimed in claim 1, characterized in that, downstream of the connection of the branch bore (14), the bore (11) connecting the pump interior chamber (9) and the tappet chamber (10) has a free flow cross section which is reduced relative to that of the branch bore (14).

9. The high pressure pump as claimed in claim 8, characterized in that, downstream of the connection of the feed bore (8), the bore (11) connecting the pump interior chamber (9) and the tappet chamber (10) has a free flow cross section which is reduced relative to that of the feed bore (8).

10. The high pressure pump as claimed in claim 1, characterized in that the suction valve (7) comprises a valve body (17), which delimits the pump working chamber (6) in the axial direction.

11. The high pressure pump as claimed in claim 10, wherein the valve body (17) is inserted into the bore (2) in the housing part (1).

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The single drawing FIGURE shows a longitudinal section through a high pressure pump according to the invention according to a preferred embodiment.

SUMMARY OF THE INVENTION

(2) The high pressure pump shown in longitudinal section comprises a housing part 12, in which a pump interior chamber 9 is formed. In the present case, the pump interior chamber 9 accommodates a drive shaft 21 with a cam 5, on which a pump piston 3 is supported via a tappet assembly 4. The tappet assembly 4 comprises a sleeve-shaped tappet body 22, in which a roller shoe 23 for the rotatable support of a roller 24 is accommodated. The tappet assembly 4 is connected to the pump plunger by a spring plate 25, wherein the spring plate 25 is acted upon in the direction of the cam 5 by the spring force of a spring 26. The spring force of the spring 26 holds the spring plate 25 and hence the pump piston 3 in contact with the tappet assembly 4.

(3) The high pressure pump shown is designed as a single-plunger pump and, for volume compensation between the pump interior chamber 9 and a tappet chamber 10 formed within the sleeve-shaped tappet body 22, has a handle-shaped bore 11, which connects the pump interior chamber 9 to the tappet chamber 10.

(4) A further housing part 1, which is referred to below as cylinder head 1, is flanged to housing part 12. A bore 2, in which the pump piston 3 is accommodated in such a way that it can be moved with a reciprocating motion, is formed in the cylinder head 1. In this case, the pump piston 3 delimits a pump working chamber 6, which is formed in the bore 2 and which is delimited by a valve body 17 of a suction valve 7 on the side facing away from the pump piston 3. The suction valve 7 is used to fill the pump working chamber 6 with fuel. For the purpose of supplying the suction valve 7 with fuel, a feed bore 8 is formed in the cylinder head 1, beginning at a flange surface 13 of the cylinder head 1 and ending at an annular chamber 20, which surrounds the valve body 17 of the suction valve 7. Via a branch bore 14 formed in the housing part 12, the feed bore 8 of the cylinder head 1 is connected to the handle-shaped bore 11, the connection of the suction valve 7 to a low pressure region of the high pressure pump thus being accomplished by this means. Accordingly, a separate feed bore for connecting the suction valve to the low pressure region can be eliminated. As a result, the high pressure pump shown can be produced in a simple and low-cost way.

(5) Moreover, the suction valve 7 of the high pressure pump shown is electromagnetically controllable, thus furthermore making it possible to dispense with a metering unit upstream of the suction valve 7 for volume control. Production costs and also operating costs can thereby be further reduced. For electromagnetic control, the suction valve 7 has a solenoid 15, which interacts with an armature 16, the latter being designed in the present case as a plunger-type armature. The armature 16 is connected to a valve tappet 19, which is accommodated in an axial bore 18 in the valve body 17 of the suction valve 7 in such a way as to be axially movable. When the solenoid 15 is energized, the armature 16 pushes the valve tappet 19 out of its seat, and the suction valve 7 opens. In the closing direction, the valve tappet 19 is acted upon by the spring force of a spring 27 which, for this purpose, is supported at one end on the valve body 17 and at the other end on the armature 16. When the energization of the solenoid 15 is ended, the spring 27 pushes the valve tappet 19 back into its seat, and the suction valve 7 closes. During this process, the spring 27 is supported by the pressure conditions prevailing in the pump working chamber 6 during the delivery mode of the high pressure pump.