Pump system for conveying lubricating oil

Abstract

A pump system for conveying lubricating oil to a cutting chain of a chain saw is provided. The pump system comprises at least one first oil pump, wherein a quantity of oil being conveyed thereby is adjustable by an operator of the chain saw. The pump system also includes a basic oil pump that is connected in parallel to the adjustable oil pump.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to a pump system for conveying lubricating oil to a cutting chain of a chain saw. [0002] Chain saws have a guide bar on the peripheral edge of which is guided a cutting chain having individual chain links. The pivotable connection of the chain links, as well as the cutting teeth, are subjected to high stresses during operation. To avoid excessive wear, and to achieve an improved cutting result, a lubricating oil is supplied to the cutting chain via a pump system. [0003] A certain quantity of oil is desired depending upon the material that is to be cut. With different types of wood that are to be cut, it has been shown that different quantities of lubricating oil are expedient for a good cutting result. For this purpose, pump systems are known having oil pumps that can be adjusted by an operator, where the operator of a chain saw can adapt the quantity of lubricating oil being supplied to the material that is to be cut....

AI Technical Summary

Benefits of technology

[0018] Thus, a pump system is proposed according to which a basic oil pump is connected in parallel to at least one adjustable oil pump. In this connection, the basic oil pump conveys a basic quantity of oil that even under cold operating conditions, and a lubricating oil that has a correspondingly high viscosity, ensures a basic supply of lubricating oil to the cutting chain. By means of the oil pump that is connected in parallel and that can be adjusted by an operator, an additional quantity of oil can be supplied to the cutting chain as a function of need. In this connection, there is no adverse impact upon the basic supply via the basic oil pump. An incorrect setting of the adjustable oil pump, or even changing environmental conditions, do not lead to an undersupply of lubricating oil.

[0019] It can be expedient to make the basic oil pump adjustable. For example, by adjusting the basic oil pump it can be possible to adapt the basic capacity to a specific type of wood or to a specific type of lubricating oil, whereas via the adjustable oil pump fluctuations of the operating parameters, for example as a consequence of fluctuations in viscosity due to the temperature, are compensated for. Pursuant to an expedient further development, the capacity of the basic oil pump is fixed. This prevents the user from unintentionally making an incorrect adjustment. The adjustable oil pump advantageously has a reduced maximum capacity in comparison to the basic oil pump. Incorrect adjustments of the pump system are prevented via the appropriately small adjustment range.

[0020] Pursuant to an advantageous further development, the oil pump is embodied as a piston pump having a piston portion that can be rotatably driven about its longitudinal axis, whereby a peripheral inclined groove is provided on the piston portion into which a control pin that is fixed to a housing in the axial direction extends. The piston portion can be continuously rotatably driven, whereby via the control pin and the inclined groove, an oscillating axial movement is produced with little mechanical effort. Such a pump has a straightforward construction and furthermore has a good service life with little mechanical wear.

[0021] Pursuant to an expedient further development, a respective piston of the two pumps is fixed in position on a common piston portion, and in so doing is in particular monolithically embodied with the piston portion. To drive the two pistons, only one corresponding piston portion is required. The pump is embodied as an integral component that is compact and straightforward. Only a single drive is necessary for both pumps. In this connection, the pistons advantageously have different diameters, whereby they are guided in a correspondingly stepped cylinder bore that is provided in a pump housing that in particular has a monolithic configuration. The different pump diameters lead to different capacities for the two pumps, whereby the smaller piston diameter, in conjunction with the adjustable oil pump, leads in a desired manner to a reduced maximum conveying capacity. With a stepped cylinder bore, the sealingly guided piston having the smaller diameter at the same time also effects a sealing of the cylinder space in which the larger piston is guided. Separate sealing means are not necessary. The pump has a straightforward construction and is economical to manufacture.

[0022] For an easy adjustability of the oil conveying capacity, the arrangement of a line valve, especially on the intake side of the adjustable oil pump, can be expedient. A line valve has a straightforward construction, and due to the arrangement on the intake side prevents pressure peaks in the pump when the valve is closed. The line valve can be embodied as a control valve, by means of which an additional quantity of oil can selectively be activated or deactivated. Pursuant to an expedient further development, the line valve is embodied as a control valve that is in particular infinitely variable. For this purpose, an embodiment as a rotary piston valve is particularly suitable. The additional quantity of oil that is conveyed via the adjustable oil pump can be regulated in a finely sensitive manner. The mechanical outlay, and hence the cost, is low.

Problems solved by technology

The pivotable connection of the chain links, as well as the cutting teeth, are subjected to high stresses during operation.

However, this can change during operation.

It has been shown that the viscosity-dependent capacity is subjected to unexpectedly high fluctuations.

An at least approximately optimum oil capacity at operating temperature can, after a longer period of interruption of operation, and with the lubricating oil cooled off, result in the initially conveyed quantity of oil being too little.

An excessive wear of the cutting chain can result.

Similarly, if the quantity of oil conveyed is too low, the cutting result can be unsatisfactory.

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