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Compressor unit

Compressor unit description/claims

This is a continuing application, under 35 U.S.C. § 120, of copending international application No. PCT/EP2006/068011, filed Nov. 1, 2006, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German patent application DE 10 2005 060 320.3, filed Dec. 16, 2005; the prior applications are herewith incorporated by reference in their entirety.

The invention relates to a compressor unit, in particular for air compression within portable/transportable appliances. The compressor unit has at least one motor and a reciprocating piston compressor driven via a slider crank mechanism. The slider crank mechanism consists of a crank wheel and a connecting rod connected to the crank wheel and to a piston.

In such piston compressors, in particular in very simple piston compressors that are produced in large quantities, such as, for example, small compressors for the filling of tires, it is desirable to keep the maximum pressure within specific limits, so that, on the one hand, no material overload occurs on the compressor components or a high compressor power and service life can be achieved, along with an economical use of material, and, on the other hand, pressure filling takes place only up to a maximum pressure without further costly regulating devices.

To set the maximum pressure in the working space of the piston compressor, there are some known methods whereby a volumetric displacement setting and therefore a pressure setting can be carried out by a variation in the dead air volume. What is in this context designated as dead air volume or also as “harmful volume” is that part of the cylinder volume, delimited by the piston head and the cylinder walls, which still remains between the piston head and cylinder wall after the completion of the compression stroke.

These methods include, for example, the assembling of the components—to be precise, the piston, the connecting rod, the cylinder, and the cylinder head—with correspondingly suitable tolerances. This, however, can be carried out successfully only in the case of a sufficiently accurate production of the individual parts and even then remains a costly compromise.

A further method is to introduce cylinder head gaskets of differing thickness, by means of which the dead air volume can likewise be influenced. However, this is basically a labor-intensive and merely gradual approximation to the correct pressure conditions.

A further solution is pressure relief valves in the piston head or in the cylinder walls, said valves opening at a maximum pressure. Apart from the additional components required, in this solution the pressure pulses and the generation of noise occasionally present problems.

German published patent application DE 10 2004 015 618 A1 discloses an axial piston compressor with a variable and regulatable volumetric displacement, in which essentially the pressure in the engine chamber can be regulated (closed-loop controlled) in real time by one or more regulating valves. What is in that context designated as the engine chamber or else “regulation volume” is the space in which the piston drive mechanism is arranged. Regulation takes place with the aid of an algorithm taking into account one or more operating parameters, and the regulating valves are arranged such that the engine chamber can be connected either to the suction side and/or to the high-pressure side.

This is intended primarily to prevent icing-up which could occur due to an excessive lowering of the pressure on the suction side. In the case of simple and small axial piston compressors in which the intake air flows through the piston drive housing of the compressor, that is to say in which the low-pressure or suction side and the engine chamber coincide, such complicated regulation cannot be implemented.

Moreover, in the powers of small compressors, icing-up on the low-pressure side is less important than to limit the maximum pressure on the high-pressure side, in order either to achieve better material utilizations or else make manufacturing tolerances capable of being handled for large series manufacture.

It is accordingly an object of the invention to provide a compressor unit which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a compressor construction which allows a highly accurate setting of the maximum pressure without high outlay independently of types of manufacture and manufacturing tolerances, so that the reworking of components is avoided.

With the foregoing and other objects in view there is provided, in accordance with the invention, a compressor unit, comprising:

at least one motor;

a reciprocating piston compressor with a piston having a given piston stroke;

a slider crank mechanism connected for driving the reciprocating piston compressor, the slider crank mechanism including a crank wheel, a connecting rod connected between the crank wheel and the piston, and a threaded connection for adjusting the piston stroke within the slider crank mechanism.

In other words, the objects of the invention are achieved in that means for adjusting the piston stroke is arranged within the slider crank mechanism which consists of a crank wheel and of a connecting rod connected to the crank wheel and to a piston. By virtue of such a design, the piston stroke and consequently the remaining dead air volume and the maximum pressure can be set in the simplest possible way during assembly, with the remaining dimensions and tolerances being given.

In an advantageous design, a connection adjustable in length in the sliding direction is arranged between the piston and connecting rod.

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