阅读说明：本技术 切换装置和润滑泵 (Switching device and lubricating pump ) 是由 D.赫斯 J.克雷茨凯默尔 S.舒尔曼 于 2020-04-02 设计创作，主要内容包括：一种用于将润滑泵的液压驱动器的管路交替地连接到液压回路的压力管路和返回管路的切换装置,包括：连接至液压驱动器的管路的液压管路和连接至压力管路和返回管路的其他液压管路,切换阀,其配置成与液压管路相互作用,使得在切换装置的第一切换状态下,液压驱动器的管路中的至少第一管路可连接至压力管路,并且在切换装置的第二切换状态下,液压驱动器的管路中的至少第二管路可连接至压力管路,包括液压控制管路的液压控制单元,其中控制管路中的至少第一控制管路可连接至压力管路,控制管路中的第二控制管路配置为切换管路,使得切换阀可通过它们在第一切换状态和第二切换状态之间切换,与控制管路相比,液压管路可传导不同体积流量的液压流体。(A switching device for alternately connecting a line of a hydraulic drive of a lubrication pump to a pressure line and a return line of a hydraulic circuit, comprising: a hydraulic line connected to the lines of the hydraulic actuator and further hydraulic lines connected to the pressure line and the return line, a switching valve configured to interact with the hydraulic lines such that in a first switching state of the switching device at least a first one of the lines of the hydraulic actuator is connectable to the pressure line and in a second switching state of the switching device at least a second one of the lines of the hydraulic actuator is connectable to the pressure line, a hydraulic control unit comprising hydraulic control lines, wherein at least a first one of the control lines is connectable to the pressure line and a second one of the control lines is configured to switch the lines such that the switching valve is switchable by them between the first switching state and the second switching state, the hydraulic lines being conductive with a different volume flow of hydraulic fluid compared to the control lines.)

1. Switching device for alternately connecting the lines of a hydraulic drive of a lubrication pump (1) to the pressure line and to the return line of a hydraulic circuit, comprising the following features:

a hydraulic line connectable to the lines of the hydraulic actuator and further hydraulic lines connectable to the pressure line and the return line,

a switching valve configured to interact with the hydraulic line such that in a first switching state of the switching device at least a first of the lines of the hydraulic drive is connectable to the pressure line and in a second switching state of the switching device at least a second of the lines of the hydraulic drive is connectable to the pressure line,

a hydraulic control unit comprising hydraulic control lines, wherein at least a first of the control lines is connectable to the pressure line,

-wherein a second of the control lines is configured as a switching line such that the switching valve can be switched by them between a first switching state and a second switching state,

-wherein the hydraulic line and the control line are configured such that the hydraulic line can conduct a different volume flow of hydraulic fluid than the control line.

2. The switching arrangement of claim 1, wherein the switching valve is configured to cooperate with hydraulic lines such that in a first switching state a second of the lines is connectable to a return line and in a second switching state a first of the lines is connectable to a return line.

3. The switching device according to claim 1 or 2, wherein the switching valve and the hydraulic lines are configured to cooperate such that in a first switching state of the switching device at least one first one of the hydraulic lines connectable to the lines of the hydraulic actuator is connected to at least one of the hydraulic lines connectable to the pressure lines, and in a second switching state of the switching device at least one second one of the hydraulic lines connectable to the lines of the hydraulic actuator is connected to at least one of the hydraulic lines connectable to the pressure lines.

4. The switching device according to any one of claims 1 to 3, wherein the switching valve is configured as a switching piston (55) cooperating with two switching chambers (63, 64), and the switching chambers (63, 64) are connected to a switching line of a switching unit.

5. The switching device according to one of claims 1 to 4, further comprising at least one regulating unit which is configured in a manner cooperating with the switching valve such that the volume flow which can be conducted through the hydraulic line in the switched state of the switching device is adjustable.

6. The switching device according to any one of claims 1 to 5, wherein the control unit comprises a progressive distributor (16).

7. Switching device according to claim 6, wherein the two outlets of the progressive distributor (16) are connected to or form a switching line.

8. The switching device according to any one of claims 6 or 7, wherein the progressive distributor (16) comprises at least two control pistons (I, II, III) hydraulically connected to a portion of the control line and configured to be controllable by them.

9. The switching device according to any one of claims 6 to 8, wherein the progressive distributor (16) comprises a pressure limiting valve (30).

10. A lubrication pump comprising the following features:

a hydraulic drive comprising lines for connection to the pressure line and the return line of the hydraulic circuit,

-a pumping unit for lubricant, which pumping unit is connected to and designed to be drivable by a hydraulic drive, and

-a switching device according to any one of claims 1 to 9, connected to the line of a hydraulic actuator.

Technical Field

The invention relates to a switching device and a lubrication pump.

Background

A series of differently designed lubricating pumps are known from the prior art, which pumps are used, for example, for lubricating hydraulically driven tools. One application case is lubricating hydraulic impact tools, such as hydraulic hammers for construction machines. In this case, embodiments are known in which the drive is effected by means of a hydraulic circuit of the tool or the construction machine without an own energy source. The hydraulic circuit for a striking tool is characterized in that the hydraulic pressure is repeatedly raised and lowered. The change between the pressure increase and the pressure decrease produces an impact motion of the striking tool. Many other applications of lubrication pumps for lubricating hydraulic tools and other machinery are known.

From DE102006026274a1 a lubrication pump is known, in which a drive piston is configured in a double-acting manner with two drive chambers, and a switchable and hydraulically actuatable switching unit is provided, by means of which the drive chambers can be alternately connected in operation to a pressure line of a hydraulic circuit. The switching unit is configured as a progressive distributor operated by the hydraulic circuit.

Disclosure of Invention

The object of the present invention is to provide an improved and flexibly usable switching device and a lubrication pump for such a switching device.

This object is achieved by the subject matter of claim 1 and claim 10. Advantageous embodiments are described in the dependent claims.

According to claim 1, as a preferred embodiment of the invention, a switching device for alternately connecting the lines of a hydraulic drive of a lubrication pump to the pressure line and to the return line of a hydraulic circuit is provided, comprising the following features:

a hydraulic line connectable to the lines of the hydraulic actuator and further hydraulic lines connectable to the pressure line and the return line,

a switching valve configured to interact with the hydraulic line such that in a first switching state of the switching device at least a first of the lines of the hydraulic drive is connectable to the pressure line and in a second switching state of the switching device at least a second of the lines of the hydraulic drive is connectable to the pressure line,

a hydraulic control unit comprising hydraulic control lines, wherein at least a first of the control lines is connectable to the pressure line,

-wherein a second of the control lines is configured as a switching line such that the switching valve can be switched by them between a first switching state and a second switching state,

-wherein the hydraulic circuit and the control circuit are configured such that the hydraulic circuit can direct a different volume flow of hydraulic fluid than the control circuit.

The invention is based in particular on the recognition that in the known lubrication pumps comprising a hydraulic control unit, the hydraulic fluid flowing through the control line is also led into the hydraulic drive for the driving thereof. It is further recognized that in the design of lubrication pumps for various applications and requirements (e.g., various pumping capacities), hydraulic drives require different sizes and therefore different hydraulic fluid volumetric flows for smooth operation. For this purpose, the lines are correspondingly larger or smaller in size, in order to be able to deliver larger or smaller quantities of hydraulic fluid per unit time. In the known embodiment of such a lubricating pump, it is then necessary to design all the lines correspondingly larger or smaller. Furthermore, the invention is based on the recognition that: the control unit itself does not require a particularly large volume flow to perform its function. Therefore, two logical internal hydraulic circuits are provided in the switching device, namely: the hydraulic control circuit provided by the hydraulic lines on the one hand and the control lines on the other hand, through which the different volume flows are guidable despite the fluid connections. The switching valve regulates the fluid connection between different hydraulic lines in the hydraulic drive circuit driven by the hydraulic driver by periodically connecting the lines of the hydraulic driver alternately to the pressure line and to the return line via the hydraulic lines of the switching device. The switching process between these two switching states is in turn driven by the same hydraulic control unit, i.e. a hydraulic control circuit, which comprises a control line. The control unit is preferably driven by the same hydraulic circuit "external" with respect to the switching device, which provides the pressure line and the return line.

Thus, the control line can be made compact, independent of the volume flow required for the operation of the hydraulic drive, which reduces the space and material requirements of the control unit.

The control unit may preferably comprise a hydraulic control element, by means of which hydraulic control pulses can be generated, which can be transmitted via the switching line and by means of which the switching process of the switching valve can be triggered. The control element is preferably embodied to be movable.

The switching device can in principle be configured in a modular and flexible manner in connection with the hydraulic drive and the hydraulic circuit. It is also possible to integrate it completely into the lubricating apparatus, so that the respective first hydraulic line is permanently connected to the first line of the hydraulic drive, or to configure the connected hydraulic line and the line of the hydraulic drive virtually as one line. Depending on the switching state, different hydraulic lines are connected to one another by the switching process of the switching valve, so that the hydraulic drive operates as described above.

The switching valve and the hydraulic lines are preferably configured to interact such that in a first switching state of the switching device at least one first of the hydraulic lines connectable to the lines of the hydraulic actuator is connected to at least one of the hydraulic lines connectable to the pressure lines, and in a second switching state of the switching device at least one second of the hydraulic lines connectable to the lines of the hydraulic actuator is connected to at least one of the hydraulic lines connectable to the pressure lines.

In a first switching state of the switching device, the switching valve is preferably configured to interact with the hydraulic lines such that at least one of the second lines of the hydraulic drive is connectable to the return line, and in a second switching state of the switching device at least one of the first lines of the hydraulic drive is connectable to the return line.

In a preferred embodiment of the invention, the switching valve is configured as a switching piston interacting with two switching chambers, and the switching chambers are connected to the switching line of the switching unit. Hydraulic fluid can be alternately led to one control chamber via the control line, while the other is connected to the return line. This triggers a switching process of the switching piston, which moves back and forth in the chamber.

In a preferred embodiment of the invention, the switching device comprises at least one regulating unit which is configured to interact with the switching valve such that, in a switching state of the switching device, the volume flow which can be conducted by the hydraulic line is adjustable. The structurally identical switching devices can therefore be used to drive and control a plurality of hydraulic drives having different requirements with regard to the volume flow, which increases their range of use and reduces the structural outlay.

In a preferred embodiment of the invention, the control unit comprises a progressive distributor. The progressive distributor may advantageously be used to control the switching valves and be driven by the hydraulic circuit. No separate driver is required but is technically feasible.

In a preferred embodiment of the invention, the two outlets of the progressive distributor are connected to or form a switching line. The switching valve can therefore be switched with relatively low forces directly according to the known operating methods of progressive dispensers.

In a preferred embodiment of the invention, the progressive distributor comprises at least two control pistons hydraulically connected to a portion of the control line and configured to be controllable thereby. Particularly preferably, it comprises three control pistons. A particularly reliable operation is ensured here.

In a preferred embodiment of the invention, the progressive distributor comprises a pressure limiting valve. The pressure limiting valve may be configured such that it is set to open at a fixed pressure. However, an adjustable pressure limiting valve may also be provided.

According to claim 10, there is provided a lubrication pump comprising the following features:

a hydraulic drive comprising lines for connection to the pressure line and the return line of the hydraulic circuit,

-a pumping unit for lubricant, which pumping unit is connected to and designed to be drivable by a hydraulic drive, and

-a switching device according to any one of claims 1 to 9, connected to the line of a hydraulic actuator.

Accordingly, there is thus provided a lubrication pump comprising: hydraulic drive comprising lines for connection to the pressure line and return line of the hydraulic circuit, and a pumping unit for lubricant, designed to be connected to and drivable by the hydraulic drive, wherein the hydraulic drive comprises a switching device comprising the following features:

a hydraulic line connectable to the lines of the hydraulic actuator and further hydraulic lines connectable to the pressure line and the return line,

a switching valve configured to interact with the hydraulic line such that in a first switching state of the switching device at least a first of the lines of the hydraulic drive is connectable to the pressure line and in a second switching state of the switching device at least a second of the lines of the hydraulic drive is connectable to the pressure line,

a hydraulic control unit comprising hydraulic control lines, wherein at least a first of the control lines is connectable to the pressure line,

-wherein a second of the control lines is configured as a switching line such that the switching valve can be switched by them between a first switching state and a second switching state,

-wherein the hydraulic circuit and the control circuit are configured such that the hydraulic circuit can direct a different volume flow of hydraulic fluid than the control circuit.

Such a lubrication pump can easily be structurally designed to meet various requirements, since in most cases the control unit can be implemented identically or with only minor modifications.

Drawings

The advantages, features and details of the present invention result from the following description of exemplary embodiments of the invention with reference to the drawings.

Figure 1 shows a lubrication pump according to an embodiment of the invention,

figures 2 and 3 show schematic views of a switching device in various operating states according to an embodiment of the invention,

figures 4 and 5 show schematic diagrams of a control unit, an

Fig. 6 shows a further embodiment of the switching device.

Detailed Description

In fig. 1, a lubrication pump 1 is depicted as an embodiment of the present invention. It is configured as a piston pump comprising a pump tube 3. The pump tube 3 shown in the figures is shortened and may have different lengths or diameters depending on design and requirements. The pump tube 3 comprises a plurality of openings 7 on the lower end 5, through which openings lubricant for pumping can be received. A pumping piston 9 is arranged in the pump tube 3, which pumping piston 9 may be one or more parts. As does the pump tube 3. The diameter of the pumping piston 9 is configured to be smaller than the pump tube 3, so that a pumping space 8 is created between the pumping piston 9 and the pump tube 3.

The pump tube 3 is attached in the housing 11 at the upper end. The pump tube 3 projects into a recess of the housing 11, in which a hydraulic drive cylinder 13 is arranged. A drive piston 15 is movably arranged in the drive cylinder 13, which drive piston 15 divides the drive cylinder 13 into two drive chambers 17 and 19. In order to fluidically separate the drive chambers 17 and 19, two seals 21 are arranged on the drive piston 15 in a radially encircling manner. The pumping piston 9 is connected to the driving piston 15 and thus movable up and down therethrough. At the upper end of the pump tube 3, a sealing unit 23 is arranged at the transition to the drive cylinder 13, which sealing unit 23 separates the pumping space 8 from the drive chamber 19. Thereby ensuring that lubricant located in the pumping space 8 cannot reach the drive chamber 19. A lubrication connection 25 is provided in the housing 11 and is connected to the pumping space, and pumped lubricant can escape through the pumping space. The respective tool or machine to be lubricated can be connected to the lubrication connection by means of a line.

For operation, the lower end 5 of the pump tube 3 is immersed in a lubricant reservoir, not shown here, and the pumping piston 9 is moved up and down by the drive piston 15. The driving of the driving piston 15 is explained in detail with reference to fig. 2 and 3. Lubricant entering the pumping space 8 is moved upwards in the pumping space 8 by the moving pumping piston 9 and is present at the lubrication connection 25.

The drive piston 15 can be hydraulically operated, for which purpose the lubrication pump 1 comprises two connections 41 and 43, which are configured, for example, as quick couplings, by means of which the lubrication pump 1 can be integrated into a hydraulic circuit, not shown here. For this purpose, the connection 41 is connected to the pressure line of the hydraulic circuit, while the connection 43 is connected to the return line, here indicated by the respective directional arrows P and R. The hydraulic fluid is thus led at constant or alternating pressure into the lubrication pump 1 via the connection 41 and is discharged again via the connection 43.

In order to move the drive piston 15 up and down, it is necessary to alternately fill the drive chambers 17 and 19 with hydraulic fluid under pressure and to evacuate them again. For this purpose, the drive chambers 17 and 19 must be alternately connected to the connections 41 and 43. When the drive chamber 17 is connected to the connection 41, i.e. the pressure line, and is to be filled with hydraulic fluid, the drive chamber 19 has to be connected to the connection 43, i.e. the return line, so that its filling level can be reduced. The pressure of the hydraulic fluid and thus the increased filling level of the drive chamber 17 moves the drive piston 15 downwards. Conversely, when the drive chamber 19 is connected to the connection 41 (i.e. the pressure line) and is to be filled with hydraulic fluid, the drive chamber 17 must be connected to the connection 43 (i.e. the return line) so that the filling level therein can be reduced. The pressure of the hydraulic fluid and thus the increased filling level of the drive chamber 19 moves the drive piston 15 upwards.

This cycle is repeated periodically during operation of the lubrication pump 1, thus requiring periodic reconnection of the drive chambers 17 and 19 to the connections 41 and 43. For this purpose, a switching device in the form of a fluid switching unit 50 is provided in the lubrication pump 1. The switching unit 50 is fluidly connected on the one hand to the drive chambers 17 and 19 via channels 27 and 29 formed in the housing 11. On the other hand, in the embodiment shown, the connections 41 and 43 are provided directly on the switching unit 50, so that hydraulic fluid from the pressure line can enter the drive chamber 17 or 19 via the switching unit 50 and the channel 27 or 29 (depending on the switching state of the switching unit 50) or can be conducted from these into the return line.

The representation of fig. 1 is merely schematic. In practical embodiments of the present invention, the switching unit 50 may be configured in different shapes and arrangements and may, for example, be integrated into the housing 11. Alternatively, it may be constructed in a modular manner and connected to the housing 11 via hydraulic hoses using quick couplings.

In fig. 2 and 3, a switching unit 50 is depicted to illustrate its function and interaction with the drive piston 15. This view is therefore constructed in a simplified manner compared to fig. 1, and only shows the necessary components in a simplified arrangement.

The switching unit 50 is divided into two sub-units configured to mate. The drive unit 51 is shown in the upper region and highlighted by the frame. In the lower region, the switching unit 50 comprises a control unit in the form of a progressive distributor 16.

Drive unit 51 includes a plurality of drive channels 71-77 connected to connections 41 and 43 and channels 27 and 29. In detail, the drive channel 71 leads from the connection 41 to the flow control valve 53, by means of which the speed of the hydraulic piston 15 can be adjusted. From the flow control valve 53, a drive channel 72 leads to the chamber 54, in which the switching piston 55 is movably arranged. The switching piston 55 is arranged to be shorter than the chamber 54 in the axial direction. Chamber 54 is connected to drive chamber 17 by drive channel 73 and drive channel 27. Chamber 54 is also connected to drive chamber 19 by drive passage 74 and drive passage 29. The chamber 54 is also connected to a drive channel 77 by two drive channels 75 and 76 and to the connection 43 by this drive channel 77.

Thus, hydraulic fluid may enter drive chamber 17 or 19 from a pressure line through drive passage 71, flow control valve 53, drive passage 72, chamber 54, and drive passage 73 or 74. Hydraulic fluid may also enter the return line from drive chamber 17 or 19 through drive passage 73 or 74, chamber 54, drive passage 75 or 76, and drive passage 77. However, the design of switching piston 55 prevents permanent fluid connection of drive channels 73, 74, 75 and 76 via chamber 54.

The switching piston 55 is generally cylindrical and is adapted with respect to its outer diameter to the inner diameter of the chamber 54. If the outer diameter is constant over the entire axial length of the switching piston 55, the outer surface of the switching piston 55 will bear completely against the inner wall of the chamber 54, fluidly separating the drive channels 73, 74, 75 and 76 from each other. In order to connect the drive channels 73, 74, 75 and 76 to each other in temporary pairs, the switching piston 55 comprises two radial grooves 56 and 57, the axial length of which corresponds to the inner diameter of the drive channels 73, 74, 75 and 76 and which are spaced apart from each other. The two switching states of the switching unit 50 are defined by the position of the switching piston 55 in the chamber 54. Here, the switching piston 55 in the illustration of fig. 2 is located on the left side of the chamber 54 and contacts the left inner wall 58 thereof. This defines the first of the two switching states. In fig. 3, the switching piston 55 is located on the right side of the chamber 54 and contacts the right inner wall 59 thereof. This defines the second of the two switching states.

In the first switching state, the groove 56 is located in the chamber 54 in such a way that: the annular chamber is located in the region of the opening of the drive channels 72 and 73 to the chamber 54, so that a fluid connection of the drive channels 72 and 73 is established. At the same time, the groove 57 is located in the chamber 54 in such a way that: the annular cavity is located in the region of the opening of the drive channels 74 and 76 to the chamber 54, thereby establishing a fluid connection of the drive channels 74 and 76. The opening of the drive channel 75 to the chamber 54 is blocked by the surface of the switching piston 55; thus, the drive channel 75 is fluidly separated from the chamber 54. Thus, in this switched state, the drive chamber 17 is connected to the pressure line, while the drive chamber 19 is connected to the return line. Thus, the drive chamber 17 is increasingly filled with hydraulic fluid, while the drive chamber 19 can be emptied simultaneously. This results in the drive piston 15 and thus the pumping piston 9 moving to the left, which is indicated by the arrow. In the illustration of fig. 1, this corresponds to an upward movement of the pumping piston 9.

In the second switching state shown in fig. 3, the groove 56 is located in the chamber 54 in such a way that: the annular chamber is located in the region of the opening of the drive channels 73 and 75 to the chamber 54, so that a fluid connection of the drive channels 73 and 75 is established. At the same time, the groove 57 is located in the chamber 54 in such a way that: the annular cavity is located in the region of the opening of the drive passages 72 and 74 to the chamber 54, thereby establishing a fluid connection of the drive passages 72 and 74. The opening of the drive channel 76 to the chamber 54 is blocked by the surface of the switching piston 55; thus, the drive channel 76 is fluidly isolated from the chamber 54. Thus, in this switched state, the drive chamber 19 is connected to the pressure line, while the drive chamber 17 is connected to the return line. Thus, the drive chamber 19 is increasingly filled with hydraulic fluid, while the drive chamber 17 can be emptied simultaneously. This results in the drive piston 15 and thus the pumping piston 9 moving to the right, which is indicated by the arrow. This corresponds to the upward movement of the pumping piston 9 in the illustration of fig. 1. In this respect, functionally, the switching piston 55 is a so-called 4/2 directional valve.

Due to the regular movement of the switching piston 55 between the end positions in the chamber 54, the drive chambers 17 and 19 are alternately connected to the pressure line or the return line, so that the drive piston 15 then moves back and forth, the lubrication pump 1 thus pumping lubricant. The movement of the switching piston 55 between its end positions in the chamber 54 is effected and controlled by the progressive distributor 16. For this purpose, the progressive distributor 16 is also connected to the pressure line and to the return line, thus also using a hydraulic circuit. A separate drive of the lubrication pump 1 is therefore not required.

The progressive distributor 16 is connected to the drive channel 71 by a control channel 81 and is connected by this channel to the connection 41 and therefore to the pressure line. The progressive distributor 16 is also connected to the drive channel 77 by a control channel 82 and to the connection 43, and therefore to the return line, by this channel. In addition, the progressive distributor 16 is connected to the chamber 54 by two control channels 83 and 84, wherein the control channel 83 opens into the region of the right inner wall 59 of the chamber 54 and the control channel 84 opens into the region of the left inner wall 58. The switching piston 55 includes a circular protrusion 61 or 62 on each end side. In the left end position of the switching piston 55, the projection 61 contacts the inner wall 58 of the chamber 54, thereby defining an annular control space 63. The control channel 84 is positioned such that it opens into the control space 63. In the right end position of the switching piston 55, the projection 62 contacts the inner wall 59 of the chamber 54, thereby defining an annular control space 64. The control channel 83 is positioned so that it leads to the control space 64, as shown in fig. 3.

The progressive distributor 16 comprises three control pistons I, II and III and is configured, on the one hand, to be able to connect the control channel 81 (and therefore the pressure line) to the control channel 83 (and therefore the control chamber 64). Here, the control channel 82 (and thus the return line) is simultaneously connected to the control channel 84 (and thus the control chamber 63). This is the situation shown in fig. 2, in which the control chamber 64 is thus connected to the pressure line, and the switching piston 55 is thus displaced or pressed by the hydraulic fluid to its left end position. The drive chamber 17 is then continuously filled with hydraulic fluid, so that the drive piston 15 moves to the left. In this state, the control pistons I, II and III are in their left end positions, which will be described in detail with reference to fig. 4 and 5.

The progressive distributor 16 is also configured to be able to connect the control channel 81 (and therefore the pressure line) to the control channel 84 (and therefore the control chamber 63). Here, the control channel 82 (and thus the return line) is simultaneously connected to the control channel 83 (and thus the control chamber 64). This is the situation shown in fig. 3, in which the control chamber 63 is thus connected to the pressure line and the switching piston 55 is thus displaced or pressed by the hydraulic fluid to its right end position. The drive chamber 19 is then continuously filled with hydraulic fluid, causing the drive piston 15 to move to the right. In this state, the control pistons I, II and III are in their right end positions.

When the drive piston 15 reaches its left end position, the progressive distributor 16 is switched to the right end position by a corresponding hydraulic drive movement of the control pistons I, II and III, switching the connection of the control chambers 63 and 64 to the pressure line and the return line, so that the switching piston 55 is moved to the right end position, and consequently the connection of the drive chambers 17 and 19 to the pressure line and the return line is also switched. The drive piston 15 is thus moved from its left end position to its right end position, in which position the connection is switched in turn due to the progressive distributor 16 and the switching piston 55.

As shown in fig. 2 and 3, the drive channels 71 to 77 are larger in diameter than the control channels of the progressive distributor 16. Due to the switching piston 55 provided between the progressive distributor 16 and the drive piston 15, two hydraulic circuits with different volume flows can be realized here. Due to the switching piston 55, the fluid connection of the control channels 83 and 84 via the chamber 54 to the drive channels 72 to 77 is prevented. The drive unit 51 comprises a relatively large diameter drive channel, in particular compared to the control channel of the progressive distributor 16. The diameter of the drive channels 71 to 77 is configured for the requirements of the respective hydraulic drive to be operated, so that the volume flow required for the pump operation can be provided.

The progressive distributor 16 contains a number of control channels of relatively small diameter, since only a relatively small volume flow of hydraulic fluid is required to perform its function, i.e. to switch the movement of the piston 55. Only the control chambers 63 and 64 need to be filled with hydraulic fluid under pressure and emptied. Thus, in many sizes and embodiments of the lubrication pump, the progressive distributor can be made very compact, in particular can be realized in the same size, regardless of the actual diameter of the drive channel. This significantly reduces the construction costs of various lubricant pump classes of different designs and sizes. In the known embodiment of such a lubrication pump, the hydraulic fluid is led directly from the progressive distributor into the hydraulic drive, so that only one hydraulic circuit is realized. For this purpose, all the channels in the progressive distributor must be dimensioned according to the volume flow required by the hydraulic drive, which means great construction costs and great demands on space and materials.

Fig. 4 and 5 show an embodiment of the progressive distributor 16 in a schematic simplified sectional view to explain its function. In fig. 4, the progressive distributor 16 is in the operating position, in which the control channel 84 and the switching chamber 63 are connected to the pressure line (through the control channel 81, here indicated by P in a simplified manner) and to the control channel 83, while the switching chamber 64 is connected to the return line (through the control channel 82, here indicated by R in a simplified manner). Fig. 5 shows the embodiment of fig. 4 in another operating position, in which the control channel 83 is connected to the pressure line P and the control channel 84 is connected to the return line R.

In the embodiment of fig. 4 and 5, the progressive distributor 16 is provided with three control pistons I, II and III, a central channel 34 connected to the pressure line P and a pressure-limiting valve 30 arranged in the central channel 34. The pressure limiting valve 30 ensures that the progressive distributor 16 switches between the control positions at the correct time, moving the switching piston 55. It is externally adjustable with respect to the hydraulic pressure that triggers it, as indicated by the arrow. Up to two outlets of the progressive distributor 16, which are connected to the switching channels 83 and 84, all the outlets 31 of the progressive distributor 16 are connected to the return line R.

At least two pairs of control lines 32 and at least one pair of outlets 31 are associated with each control piston I, II, III. Here, the first portion 32a of the first pair of control channels 32 passes through a cylinder Ia, IIa, IIIa which receives the respective control piston I, II, III and can be opened and closed by at least two piston portions 33a of the respective control piston. The first portions 32a are each open at one end thereof in the central channel 34 and transition to the second portion 32b of the control channel at the other end thereof. The second portions 32b each open at the end side of the control pistons I, II, III into a drive chamber 33b arranged therein. Thus, each control line 32 connects the drive chamber 33b of a control piston I, II, III to the central channel 34 via the piston portion 33a of the other control piston. The connection is either blocked or opened due to the respective position of the further control piston in the cylinders Ia, IIa, IIIa.

In the exemplary embodiment of fig. 4 and 5, the control channels are arranged here as follows:

the control channel 32 leading to the drive chamber 33b of the control piston II is connected to the pressure line P (fig. 4) via the control piston I. A control channel leading to the drive chamber 33b of the control piston III is led via the piston portion 33a of the control piston II. A control channel leading to the drive chamber 33b of the control piston I is led via the piston portion 33a of the control piston III. The control channels 32 are each located on both sides of the symmetrically arranged control pistons I, II, III, with the exception of the control channel guided by the control piston I via the control piston III.

The outlet 31 also extends via a piston portion 33a parallel to the first portion 32a of the control channel 32 and, like these, opens into the second portion 32b of the control channel. Here, each piston portion 33a is dimensioned such that they close either simultaneously the outlet 31 associated therewith and the first portion 32a associated therewith, or only one of them. Since a pair of control channels 32 each open into the drive chamber 33b on the end surface of the associated control piston I, II, III, each control piston moves into one of its two end positions as soon as one control channel 32 of the pair is connected to the pressure line P and the other control channel 32 of the pair is connected to the return line R.

In each case the outlet 31 is open in the end position of the control piston I, II, III, while a portion 32a of the control channel 32, which portion 32a is parallel to the outlet, is closed by a piston portion 33a, so that a second portion 32b of the control channel 32 is connected to the return line R. Furthermore, a first portion 32a of the further control channel 32a, which portion passes through the control pistons I, II, III, is open, while the outlet 31 parallel to this portion 32a is simultaneously closed by a further piston portion 33a, so that the open control channel 32 is connected to the pressure line P. Each control piston I, II, III therefore has a first operating position and a second operating position, which correspond to its two end positions in the cylinders Ia, IIa, IIIa: in the first operating position, one drive chamber 33b of the control piston, which is connected by the control channel 32, is subjected to hydraulic pressure, the other drive chamber 33b being connected to the return line R via the outlet 31. In the second operating position, the other drive chamber 33b of the control piston I, II, III is subjected to hydraulic pressure and the other drive chamber 33b is connected to the return line R. Correspondingly, with switching back and forth between the drive chambers 33b of the control pistons I, II, III, which drive chambers 33b are connected to the control channel, the drive chambers 33b of the control pistons I, II, III are alternately connected to the pressure line P in two operating positions.

The diameter of the central channel 34 is greater than the diameter of the cylinders Ia, IIa, IIIa, so that, independently of the position of the control pistons I, II, III, the entire central channel 34 is always connected to the pressure line P up to the pressure-limiting valve 30. The pressure-limiting valve 30 is arranged between the central channel 34 and the two control channels 32 via the control piston III and is configured such that it opens only when a predetermined hydraulic pressure in the pressure line P is exceeded and, depending on the position of the control piston III, connects one of the drive chambers 33b of the control piston I to the pressure line P.

The progressive distributor 16 of fig. 4 and 5 functions as follows:

in fig. 4, the control channel 84 is connected to the pressure line P via the drive chambers 33b of the control piston III and the control piston II. As the switching chamber 63 is subjected to hydraulic pressure, the switching piston 55 accordingly moves into the right end position in fig. 3. The drive piston 15 moves correspondingly according to fig. 3.

In the end position of the drive piston 15, the pressure rises in the pressure line P until a predetermined minimum switching pressure of the pressure-limiting valve 30 is reached and the pressure-limiting valve 30 is opened. Due to the open pressure-limiting valve 30, the left control channel 32 in fig. 4 of the control piston III is connected to the right drive chamber 33b in fig. 4 of the control piston I. The right outlet 31 of the control piston III is at the same time connected to the left drive chamber 33b of the control piston I. The control piston I is acted on its right end surface by the hydraulic pressure in the pressure line P and moves into its left end position, in which it connects the right control channel 32 to the right drive chamber 33b of the control piston II, while it simultaneously connects the left drive chamber 33b of the control piston II to the return line R via the outlet 31. Thus, once the control piston I is moved into the left end position, the control piston II is moved from the right end position shown in fig. 4 into the same left end position.

In the left end position, the control piston II in turn connects the right control channel 32 to the right drive chamber 33b of the control piston III, thereby connecting the control channel 83 to the pressure line P. At the same time, the control piston II closes the left control channel 32 and connects the left drive chamber 33b of the control piston III and thus the control line 84 to its associated outlet 31. The control piston III and the switching piston 55 can thus each be moved into their left end positions and then move the drive piston 15 from one right end position into the other left end position (see fig. 2).

At the end of the switching process, all control pistons I, II, III and the switching piston 55 are moved into their left end positions, as shown in fig. 5 or 2. This operating position corresponds to the operating position of fig. 2. If the pressure in the pressure line P now rises again above the minimum switching pressure, the pressure-limiting valve 30 opens again and the control pistons I, II, III move in this order from their left end position shown in fig. 5 into their right end position shown in fig. 4 in succession until the switching chamber 63 is connected to the pressure line P and the switching piston 55 has entered its right end position. Thereby completing the switching process and the driving cycle.

The progressive distributor 16 may also have only two control pistons. However, it has been shown that in this case, when starting the lubrication pump 1, sometimes a starting difficulty of the control pistons I, II, III occurs and the lubrication pump 1 is not started. The use of three or more control pistons does not present this problem. In principle, it is also possible to use more control pistons I, II, III, but this is not necessary for achieving the required function and means higher construction costs.

In fig. 6, an extended embodiment of the switching unit 50 is depicted in the form of a switching unit 50' having the same functionality as already described. Here, two adjusting screws 90 are screwed into the switching unit 50' from the outside, so that their ends 92 project into the switching chamber 54. The adjusting screw 90 can be screwed from the outside deeper into the chamber 54 and farther out than in the case shown in fig. 6. They represent adjustable stops for the switching piston 55, so that its two end positions in the chamber 54 are adjustable. In the illustration of fig. 6, the right adjusting screw 90 is rotated to such an extent into the chamber 54 that the switching piston 55 still partially closes the drive channels 72 and 75 in its right-hand end position. The same is true with respect to the drive channels 72 and 76 at the left end positions. This makes it possible to reduce the actual volume flow of hydraulic fluid to the hydraulic drive.

The principles of the present invention may be applied to many other designs of lubrication pumps and these pumps may be advantageously designed accordingly.