RECIPROCATING PISTON LUBRICATION PUMP

Abstract

A reciprocating piston lubrication pump with a component is proposed having an opening, which has at least one cylinder-shaped part, and with at least one piston, which comprises a radially outer surface built at least partly by a coating. A clearance between the radially outer surface of the piston and the component is between 1 μm and 20 μm when the radially outer surface is positioned in the cylinder-shaped part. The surface hardness of the coating at the radially outer surface is 2 to 10 times higher than that of a region of the component, which forms the cylinder-shaped part.

Claims

1. A reciprocating piston lubrication pump with a component comprising: an opening, which has at least one cylinder-shaped part, and with at least one piston, which comprises a radially outer surface built at least partly by a coating, wherein a clearance between the radially outer surface of the piston and the component is between 1 μm and 20 μm when the radially outer surface is positioned in the cylinder shaped part, and wherein the surface hardness of the coating at the radially outer surface is 2 to 10 times higher than that of a region of the component, which forms the cylinder-shaped part.

2. The reciprocating piston lubrication pump according to claim 1, wherein at least the region of the component consists of a steel, which comprises 0.8 to 1.5 weight percent of Carbon, 4.0 to 5.0 weight percent of Chromium, 1.5 to 4.5 weight percent of Vanadium, 5.5 to 6.5 weight percent of Tungsten and 4.5 to 5.5 weight percent of Molybdenum and 0.1 to 0.5 weight percent of Silicon.

3. The reciprocating piston lubrication pump according to claim 1, wherein at least the region of the component is hardened to a hardness of 700 to 900 HV at room temperature and/or to an unnotched Izod toughness of 35 to 80 J at room temperature.

4. The reciprocating piston lubrication pump according to claim 1, wherein a radially inner surface of the region of the component is machined to a roughness R.sub.z=2 to 6 μm.

5. The reciprocating piston lubrication pump according to claim 1, wherein at least a part of the coating consists of titanium carbonitride and/or TiAlSiN and/or TiSiN and/or AlCrN.

6. The reciprocating piston lubrication pump according to claim 1, wherein the coating has a thickness between 1 and 12 μm.

7. The reciprocating piston lubrication pump according to claim 1, wherein at least a base body of the piston consists of steel, which comprises 0.8 to 1.0 weight percent of Carbon, 4.0 to 4.5 weight percent of Chromium, 1.5 to 2.5 weight percent of Vanadium, 5.5 to 6.5 weight percent of Tungsten and 4.5 to 5.5 weight percent of Molybdenum and 0.1 to 0.5 weight percent of Silicon.

8. The reciprocating piston lubrication pump according to claim 1, wherein the piston comprises a hardness between 650 and 850 HV at room temperature and/or an unnotched Izod toughness between 50 and 80 J at room temperature.

9. The reciprocating piston lubrication pump according to claim 1, wherein the coating is machined to a roughness R.sub.z=1 to 5 μm.

10. The reciprocating piston lubrication pump according to claim 1, wherein a critical load L.sub.c of the coating and/or an adhesion of the coating to a base body of the piston is equal or higher than 30 N measured according to the standard ISO 20502 and/or according to the standard EN 1071-3 and/or according to the standard ASTM C1624.

11. A device with a reciprocating piston lubrication pump comprising: a reciprocating piston lubrication pump with a component comprising: an opening, which has at least one cylinder-shaped part, and with at least one piston, which comprises a radially outer surface built at least partly by a coating, wherein a clearance between the radially outer surface of the piston and the component is between 1 μm and 20 μm when the radially outer surface is positioned in the cylinder shaped part, and wherein the surface hardness of the coating at the radially outer surface is 2 to 10 times higher than that of a region of the component, which forms the cylinder-shaped part, wherein the reciprocating piston lubrication pump contains a lubricant with more than 34 weight percent of oils and less than 60 weight percent, preferably less than 50 weight percent and more preferably less than 40 weight percent of oils.

12. The device, in particular according to claim 11, wherein the reciprocating piston lubrication pump contains a lubricant with more than 10 weight percent, preferably more than 18 weight percent and more preferably more than 25 weight percent of metallic particles.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0022] Further advantages result from the following drawing description. The drawings show an embodiment of the invention. The drawings, the description and the claims contain numerous features in combination. It is advisable for the person skilled in the art to consider the features individually and to combine them into meaningful further combinations.

[0023] FIG. 1 shows an axial local section of a reciprocating piston lubrication pump according to the invention,

[0024] FIG. 2 shows an axial section of a component of the reciprocating piston lubrication pump,

[0025] FIG. 3 shows a side view of a piston of the reciprocating piston lubrication pump,

[0026] FIG. 4 shows a view on the component in axial direction.

DETAILED DESCRIPTION OF THE INVENTION

[0027] FIG. 1 shows an axial local section of a reciprocating piston lubrication pump 10 according to the invention, which comprises component 12 with an opening 14 (FIG. 2). The opening 14 has a cylinder-shaped part 16. A piston 18 of the reciprocating piston lubrication pump 10 is located partly within a region 24 of the component, which forms the cylinder-shaped part 16. The piston 18 has a radially outer surface 20 which is built by a coating 22. A clearance between the radially outer surface of the piston and the component is between two and 10 micrometers when the radially outer surface is located in the cylinder-shaped part. A surface hardness of the coating at the radially outer surface is four to eight times higher than that of the region of the component which forms the cylinder-shaped part.

[0028] The component comprises a hole 30 (FIG. 1) and a further hole (not shown) through which lubricant (not shown) is sucked into a part of the opening, which is located between the piston and a valve 26 of the reciprocating lubrication pump, when the piston is moving away from the valve during operation. Afterwards the piston is moving towards the valve 26 and causes the lubricant to be pressed through the valve and afterwards through a hole 32 (FIG. 2) of the component 12. The valve 26 is a check valve. When the piston is moved fully towards the valve 26 a spring 28 of the reciprocating lubrication pump 10 pushes the piston back and away from the valve 26.

[0029] In different embodiments the component can have different numbers of holes through which lubricant is sucked in, e. g. three or four.

[0030] The component consists of a steel, which comprises 0.8 to 1.5 weight percent of Carbon, 4.0 to 5.0 weight percent of Chromium, 1.5 to 4.5 weight percent of Vanadium, 5.5 to 6.5 weight percent of Tungsten and 4.5 to 5.5 weight percent of Molybdenum and 0.1 to 0.5 weight percent of Silicon. Furthermore, the region of the component is hardened to a hardness of 750 to 850 HV at room temperature and to an unnotched Izod toughness of 50 to 70 J at room temperature. A radially inner surface of the region of the component is machined to a roughness R.sub.z=2 to 6 μm.

[0031] The coating 22 of the piston consists of titanium carbonitride and has a thickness between 2 and 6 μm. The piston consists of a base body and the coating. The base body of the piston consists of steel, which comprises 0.8 to 1.0 weight percent of Carbon, 4.0 to 4.5 weight percent of Chromium, 1.5 to 2.5 weight percent of Vanadium, 5.5 to 6.5 weight percent of Tungsten and 4.5 to 5.5 weight percent of Molybdenum and 0.1 to 0.5 weight percent of Silicon.

[0032] The base body of the piston comprises a hardness between 700 and 800 HV at room temperature and an unnotched Izod toughness between 60 and 70 J at room temperature. The coating comprises a hardness between 3000 HV and 4000 HV. The radially outer surface of the piston, which is built by the coating, has a roughness R.sub.z between 1 and 5 μm. A critical load Le of the coating and an adhesion of the coating to the base body of the piston is equal or higher than 30 N measured according to the standard ISO 20502.

[0033] During an operation in a device the reciprocating piston lubrication pump contains a lubricant with more than 34 weight percent of oils and less than 50 weight percent of oils and with more than 18 weight percent of metallic particles.

[0034] There is a chamfer 34 on the piston front. The angle of the chamfer is 30 to 60° measured relative to a central axis 36, and the length is 0.5 to 2 mm, and the surface roughness on the chamfer is R.sub.z=1 to 6 μm.

[0035] In comparison to a conventional pump in which the piston and the cylinder are made of machinable hardened steel, the described pump, in which the piston and the component are made of the special steels and coatings, can prolong the pump service life by 4 to 100 times when pumping a special lubricants consisting of high metallic particles and/or low oil. Abrasive wear and fracture induced by metallic particles and poor lubrication induced by starved lubrication due to low oil content on the piston and the surface of the region can be minimized by the special steels and the coating, which have higher hardness, high toughness and optimized matching of the hardness between the piston coating and the surface of the region of the component.