The present invention relates to a metering valve for lubricants, comprising a metering chamber operatively connected with an inlet and an outlet with a metering piston axially movable in said chamber, dividing the chamber into a first and a second parts of varying size depending upon the axial position of the metering piston, as well as a switching member movable along a separate path, which is designed to connect alternately a first channel connected with the first part of the metering chamber with the inlet or the outlet,

whereby the highly pressurized lubricant: , depending on the position of the switching

member, can be dispensed into or out of the first part of the metering chamber.

Previously known from EP O 140 265 is a grease metering device for so-called one-piece systems. These metering devices are designed so that a sliding piston mounted in the grease metering system alternately connects a channel connected with one end of a metering chamber with an inlet or an outlet of the metering valve. The metering chamber and a metering piston movably mounted in it constitute together a metering pump which is used to dispense under high pressure the stored grease out of the chamber and the grease metering device. A drawback with this known arrangement is that the movement of the metering pump is controlled by the supply of the pressurized lubricant. For the dispensing to be carried out at the right moment the device should, for this reason comprise a sensing and control member for detecting the position of the metering piston,

or controlling the dispensing of the pressurized medium to the metering pump. The device may also be used per se for metering in a satisfactory manner pasty greases in the lubricating system, feeding but the metering pump, the separate feeding of which and the equipment that is required to control this feeding, causes this grease metering device to

be both expensive and of delicate operation.

The aim of the present invention is to provide a metering valve for lubricants of the above-mentioned type which simplifies the metering of grease by utilizing the pressure of the lubricant. The metering valve will be particularly suited for metering pasty greases in so-called one-piece systems. This is achieved according to the invention in that the other part of the metering chamber is connected with the inlet via another channel, as a result of which the pressurized lubricant can be dispensed into the other part of the metering chamber irrespective of the position of the switching member, and in that the position of the switching member is designed to be influenced by the pressure in the other part of the metering chamber in such a manner that the switching member, on a pressure rise, is displaced between a rest position, in which the feeding to the first part of the metering chamber is made possible via the channel, and an end position, in which feeding is made possible only via the first channel the switching member in an intermediate position being designed to prevent both the feeding in and the dispensing out of lubricant along the first channel.

According to a particular characteristic of the invention the metering piston has an upper side and an underside with different areas impingeable by the lubricant pressure.

According to a further particular characteristic of the invention the switching member is operatively connected with a spring operating in its axial direction which is designed to counteract the displacement of the switching member from the rest position and, after the dispensing has been completed, to return the switching member to the rest position.

According to another particular characteristic of the invention the metering piston is operatively connected with a spring acting in the axial direction of the piston, which is designed to return the metering piston to its refilling position.

According to a last particular characteristic of the invention, the length of stroke of the metering piston, which is designed to influence the amount of lubricant dispensed, is regulated by means of an adjusting screw mounted in operative connection with the piston rod.

The invention will be explained hereinbelow in greater detail with reference to the attached drawings, in which Fig. 1 is a cross-section through an advantageous form of embodiment of the invention. Fig. 2 shows another advantageous form of embodiment of the invention.

In the rest position the pressure at the inlet is below 6 90 bar. The switching member 1 is then in the position shown in Fig. 1 which allows supply to the metering chamber 8 through two channels 9a, 9b. On the supply of lubricant to the inlet the pressure in the metering chamber 8 rises. The rise in pressure causes the switching member 1 to move upwards in its run 10, as a result of which the feed to the metering chamber 8 through the upper channel 9a is inhibited. The feeding of lubricant through the lower channel 9b is, however, still permitted. The switching member 1, during the supply of lubricant, continues its upward movement until, when a specific predetermined pressure is reached in the metering chamber 8, it overcomes the spring force of a spring 3 operatively connected with the switching member and opens the connection between the upper channel 9a and the outlet 7. The metering piston is thereby urged upwards by the

pressure impinging the underside 2b of the metering piston 2, and lubricant above the metering piston 2 is dispensed out through the channel 9a to the outlet 7.

When metering is completed, the pressure in the lubricant inlet 6 is released, and the switching member is then returned to its rest position by the spring 3. When the first channel 9a between the first part 8a of the metering chamber and the inlet 6 has again opened, the metering piston 2 can be pushed back to the rest position. In the form of embodiment shown in Fig. 1 this is effected in that a difference of area between the upper side 2a and the underside 2b of the metering piston produces a residual pressure which acts upon the piston. If the residual pressure in the system is too low and is unable to return the metering piston 2 to the rest position, the latter is returned instead by the pressure rise associated with the following pumping out. New grease can thereafter be filled in the metering chamber 8, as a result of which the metering valve is ready for a new dispensing. The amount of feed can be infinitely variably regulated by means of the adjusting screw 4 which limits the displacement of the piston rod 5.

In the form of embodiment shown in Fig. 2 the metering piston 2 is operatively connected with a spring 6 which returns the piston to the rest position when the pressure in the inlet drops. The metering chamber is fitted with a sleeve 10 arranged over it, in which the spring 6 is partly mounted.

It is obvious that the invention is not to be regarded as limited to the embodiment shown in the drawing or to the example described above, and that, within the scope of the invention concept, it may be varied in many ways.