PISTON PUMP COMPRISING A PISTON WITH A PROFILED FRONT FACE

Abstract

The invention relates to a piston pump, in particular for injection systems for motorized two-wheeled vehicles and/or for motorized three-wheeled vehicles, having a compression chamber, a piston, an inlet valve, and an outlet valve. A fluid can flow into the compression chamber via the inlet valve, and the fluid can flow out of the compression chamber via the outlet valve. A region in the form of a channel, which is arranged fluidically upstream of the outlet valve, in particular directly upstream of the outlet valve, has a cross-section which is reduced compared to a compression chamber region at a distance from the outlet valve. The invention is characterized in that a piston end face facing the channel has a region which can be immersed into the channel.

Claims

1. A piston pump (1) comprising a compression chamber (9), a piston (6), an inlet valve (11), and an outlet valve (12), wherein a fluid can flow into the compression chamber (9) via the inlet valve (11), and the fluid can flow out of the compression chamber (9) via the outlet valve (12), and wherein a channel (15) forms a channel region arranged fluidically upstream of the outlet valve (12), the channel region having a cross section which is reduced in comparison with a region of the compression chamber (9) which is at a distance from the outlet valve (12), characterized in that an end face (14) of the piston (6) which faces the channel (15) has a piston region (20), wherein the piston region (20) can be made to enter into the channel (15).

2. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) is a projection on the end face (14) of the piston (6) which faces the channel (15).

3. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) has a cylindrical, conical or cuboidal geometry.

4. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) has a length M of not less than 10% of a length L of the channel (15), wherein the length M of the piston region (20) is a distance from the end face (14) of the piston (6), on which the piston region (20) is arranged, perpendicularly as far as the end face of the piston region (20) which faces the channel (15).

5. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) has at least an entry depth T into the channel (15), wherein the entry depth T is at least 5% of a length L of the channel (15).

6. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) has the same geometrical configuration as the channel (15).

7. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) is a boss.

8. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) is formed integrally with the piston (6).

9. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) is connected materially to the piston (6).

10. The piston pump (1) as claimed in claim 1, wherein the channel region is arranged directly upstream of the outlet valve (12).

11. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) has at least an entry depth T into the channel (15), wherein the entry depth T is at least 15% of a length L of the channel (15).

12. The piston pump (1) as claimed in claim 1, characterized in that the piston region (20) is connected materially, by welding, to the piston (6).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIGS. 1a and 1b show a first example of a piston pump according to the invention

[0017] FIGS. 2a and 2b show a second example of a piston pump according to the invention

DETAILED DESCRIPTION

[0018] Two illustrative embodiments of the piston pump 1 according to the invention are shown in FIG. 1 and FIG. 2. The two illustrative embodiments differ in the precise configuration of the region 20 arranged on the end face 12 of the piston 6 which faces the channel 15. Part a) of each of the two figures shows a schematic illustration of a piston pump 1, wherein the basic construction of the piston pump 1 is the same in both illustrative embodiments. Part b) of each of the two figures shows an enlargement of the region X marked by a circle in part a) of the figures.

[0019] The basic construction of the piston pump 1 is described below. The piston pump 1 has a housing 2, an armature plate 3 and, for example, a solenoid 5 or solenoid set arranged in the housing 2. A cylinder 4 is arranged in the solenoid 5. A movable piston 6 is, in turn, arranged in the cylinder 4. The magnetic field produced by the solenoid 5 moves the piston 6 in the direction of the armature plate 3. On its side facing the piston 6, the armature plate 3 has a stop, against which the piston 6 strikes when the solenoid 5 is energized, i.e. when the magnetic field is switched on. The side of the piston 6 which faces the armature plate 3 is referred to as the piston rear side 10. The surface by means of which the piston rear side 10 touches the stop of the armature plate 3 when the magnetic field is switched on is referred to as the contact surface. The end face 14 of the piston 6 situated opposite the piston rear side 10 is also referred to as the piston front side.

[0020] A piston spring 7 is arranged between the piston 6 and the armature plate 3. The piston spring 7 is fixed on the side thereof facing the armature plate 3 by a spring holder 8. The piston spring 7 can be arranged partially or completely within the piston 6 or in a cavity arranged in the piston 6. The piston rear side 10 has an opening, through which the piston spring 7 projects from the piston. The piston spring 7 is compressed owing to the movement of the piston in the direction of the armature plate 3. After the magnetic field is switched off, the piston spring 7 pushes the piston 6 back in the opposite direction.

[0021] An inlet valve 11 and an outlet valve 12 are furthermore arranged in the cylinder 4, in particular in the cylinder bottom. The cylinder 4 is delimited by the armature plate 3 on one side and by the cylinder bottom on the opposite side. A compression chamber 9 is arranged within the cylinder 4. The compression chamber 9 is delimited by the cylinder walls, the inlet valve 11 and the piston 6.

[0022] The inlet valve 11 and/or the outlet valve 12 can be designed as Belleville springs. The inlet valve 11 and the outlet valve 12 and thus also the inlet and the outlet are arranged on the same side of the cylinder 4 or of the compression chamber 9. The compression chamber 9 is arranged fluidically between the inlet valve 11 and the outlet valve 12. A valve body 13 is arranged between the inlet valve 11 and the outlet valve 12. A channel 15 is formed within the valve body 13. Typically, the length of the channel 15 corresponds to the length of the valve body 13. The outlet valve 12 is connected to the compression chamber 9 by means of the channel 15, thus allowing the fluid to flow from the compression chamber 9 to the outlet valve 12 via the channel 15.

[0023] Fuel lines, via which a fuel is drawn into the compression chamber 9 within the cylinder 4 from a tank through the inlet valve 11 owing to the vacuum, are not shown. The vacuum in the cylinder 6 or in the compression chamber 9 is produced by the movement of the piston 6 in the direction of the armature plate 3. The fuel is forced from the piston 6 to an injection valve via further fuel lines and the outlet valve 12.

[0024] In the first illustrative embodiment, which is shown in FIG. 1, the region 20 is designed as a cylindrical protrusion. The region 20 has a length M of 93% of the length L of the channel 15. The entry depth T of the region 20 in the channel 15 is 90% of the length L of the channel 15. The fact that the diameter of the region 20 is matched to the diameter of the channel 15, i.e. the difference between the two diameters of the region 20 and the channel 15 is less than 10% of the diameter of the channel 15, ensures that the dead volume in the channel 15 is effectively minimized and, at the same time, as little friction as possible is produced between the region and the channel wall.

[0025] In the second illustrative embodiment, which is shown in FIG. 2, the region is designed as a boss. The boss has a length M of 15% of the length L of the channel and an entry depth T of 11.5% of the length L of the channel.