HK1030040B - Lubricating device for a plurality of lubricating stations - Google Patents

Description

Lubricating device with multiple lubricating points and lubricating method

Technical Field

The invention relates to a lubricating device and a lubricating method for multiple lubricating points, preferably using oil as a lubricant, which is fed to the lubricating points of a knitting machine.

Background

For example, in a knitting machine, a needle transmission needs to be lubricated continuously, and the same is true for a needle guide plate, a needle cylinder, and the like of a needle bed. Good periodic lubrication is of great significance in particular for modern high-speed operating knitting machines. All lubricating points must be reliably supplied with lubricating oil. Interruption of lubrication usually results in increased wear and immediate stoppage of the knitting machine. On the other hand, a moderate lubrication is necessary. It is not advisable to feed too much lubricating oil to the lubricating points. For this reason, most of these machines are equipped with so-called pressure lubricators or pressure oil lubricators, which deliver the lubricating oil under pressure from a central point to the various lubricating points through suitable ducts.

For this purpose, for example, EP 0499810B 1 discloses a lubricating device which allows reliable and metered lubrication of a plurality of lubricating points. The lubricating apparatus has a lubricant container in which a piston pump is placed. The outlet of the piston pump is connected to an electric distributor valve, so that the outlet of the pump can be connected to a lubricant line selected from a group of lubricant lines.

Disclosure of Invention

The object of the invention is to provide a simplified lubricating apparatus on this basis. Furthermore, it is an object of the invention to provide an improved lubrication method.

The technical solution of the above object in terms of equipment consists in a lubrication device of multiple lubrication points comprising:

a pump device for delivering lubricant to said lubrication points,

a distribution device for distributing the lubricating portion to one of the multiple lubricating points, wherein the pump device has a piston mounted in a cylinder for axial movement;

characterized in that, for forming the distribution device, discharge channels are provided in the cylindrical cylinder wall of the cylinder of the pump device, which discharge channels are connected to one of said multiple lubrication points via a pipe, respectively, at least one control groove is provided on the circumferential surface of the piston of the pump device, which control groove is selectively aligned with at least one discharge channel by rotation of the piston, so that the selected discharge channel is connected to the working space in the cylinder of the pump device, axial displacement of the piston by a pumping movement for delivering lubricant to the lubrication points and a transmission device for selecting the discharge channel and for rotating the piston, which transmission device has a stepping motor which is rotationally driven to select the discharge channel when the piston is connected in a rotationally fixed manner via a coupling device, which selection of the discharge channel is performed when said rotationally fixed connection is released by the coupling device and the piston is stopped by a stopping device for rotation of the piston via a transmission mechanism So that the piston moves axially and the transmission mechanism converts the rotation of the step motor into linear motion.

The above object is achieved in a method aspect by a method for lubricating multiple lubrication points of a machine with at least one pump device via a plurality of pipes, wherein lubricant is supplied by the pump device via a selected pipe to one or more selected lubrication points, characterized in that the injection pressure established by the pump device is adjusted in a pulsed manner within a lubrication interval, for which purpose the piston of the pump device is driven stepwise such that lubricant is intermittently injected from the nozzle to the selected lubrication point.

The lubricating apparatus of the invention is provided with a distribution device with which the lubricant supplied by the pump is distributed to selected oil lines and thus delivered to selected lubricating points. Wherein the dispensing device and the pump constitute one unit. The construction of the lubricating apparatus is greatly simplified by the distributor device and the pump constituting one unit. Furthermore, the control of the lubricating apparatus can be simplified.

The pump is a piston pump and has a piston which is axially displaceable in a pump cylinder. The piston and the pump cylinder together form a pump unit. Further, the pump cylinder and the piston constitute a control mechanism. For this purpose, the piston is rotatably mounted in the pump cylinder and is provided with control surfaces or control passages which correspond to control grooves or discharge openings arranged in the pump cylinder. The piston can be provided with at least one control groove on its circumferential surface, which is formed such that it can be rotated into correspondence with the at least one outlet passage by a corresponding rotational positioning of the piston. If desired, the arrangement may be such that the control slot may be turned to coincide with a plurality of outlet passages. The control channel and the outlet channel are arranged such that the working space defined by the piston in the pump cylinder communicates with the respectively selected outlet channel over the entire stroke of the piston. The entire oil volume pressed out by the piston can thus be fed into the outlet passage. The pump thus constructed is both a pump device and a dispensing device.

The pump means and the dispensing means may be connected to a transmission means which causes the piston to rotate and move. The displacement movement is the movement of the pump, so that the displacement transmission constitutes a pump transmission. When no displacement movement is performed, the rotational movement of the piston does not cause a volume change in the pump cylinder, so that the rotational movement only controls the closing or opening of the discharge channel. Thus, the rotary drive is a distributor drive and the piston is a control slide. Pumping and switching can be caused independently by rotation and displacement of the piston, respectively. This can be done by means of a separate transmission or by means of a combined transmission which produces both a rotary and a displacement movement.

The rotation of the piston is preferably effected by a stepper motor which produces the required rotational adjustment movement. The selection of a discharge path and the rotational positioning of a lubrication point can be carried out simply by means of the stepping motor. But such a stepper motor may also produce a displacement movement of the piston. For this purpose, the piston is preferably connected to the stepping motor or another servomotor via a clutch which allows a defined or adjustable rotational play first, wherein the relative rotation in the rotational play is converted into the required linear movement via a gear mechanism.

The angle of rotation of the rotating gap can be used to produce a linear motion. For this purpose, the piston is preferably connected to a locking mechanism which holds the piston in any or selected rotational position without rotation, but does not lock it against axial displacement. Such a locking mechanism may, for example, be constituted by a ratchet wheel which can be engaged and disengaged with a locking element. The engagement and disengagement is preferably achieved by a suitable radial movement of the locking element, for example by means of an attracting magnet. In the case where the piston is held against rotation, the rotation of the stepping motor can be performed within the range of the rotation gap of the clutch. The displacement means is preferably constituted by a transmission mechanism which converts relative rotation between the piston and the rotary means into linear movement of the piston.

In a particularly long-lived and simple design, the ratchet wheel is designed as a detent wheel. The stop member functions as a stop pawl so that the stop pawl can rotate the ratchet in a selected direction. Furthermore, the locking pawl can be released, for example, by means of a lifting magnet, so that the ratchet wheel can be rotated in the other rotational direction. The arrangement thus provided allows normal operation of the lubricating apparatus with little manipulation of, for example, the lifting magnet release and pawl stop used. A long life can be achieved even with simple and inexpensive lifting magnets.

The transmission mechanism may be formed by two mutually engaging threaded elements. The pitch of the threaded element is designed such that a complete piston stroke is achieved by a relative rotation between the piston and the servomotor within the range of the rotational play of the coupling device. The piston is reciprocated by forward or reverse rotation of the servo motor.

If necessary, other devices may be used as the transmission. For example, a cam gear arrangement may be used which effects reciprocating movement of the piston when the rotary drive rotates in a given direction. The cam mechanism is formed by a corrugated annular groove in the sleeve wall, in which a radially extending pin driven by a servomotor is constantly moved.

The transmission mechanism generating the linear movement is preferably preloaded. This can be achieved, for example, by means of a magnet which is held in contact with the sliding side of the transmission. This is particularly advantageous for correct metering of the lubricant. When the gear mechanism rotates in the opposite direction, for example when switching from one forward stroke of the piston to one return stroke of the piston, the reversal point is precisely determined, so that metering errors are avoided.

The discharge channel and the intake channel leading from the pump cylinder are preferably each provided with a non-return valve. In this way, the pump device itself is sufficient without further control means. The non-return valve is preferably an automatic valve controlled by an applied pressure difference. Thus, no other valve control means is required.

In order to monitor the proper operation of the lubricating apparatus, a sensor is preferably provided which detects and monitors the stroke movement of the piston. It is only necessary to monitor whether the piston has reached a certain stroke. For example, when one lubrication passage is blocked, the piston does not pump lubricant into that passage and stops. Thus, the piston cannot reach the switching point of the sensing device. The sensor device detects this and switches off the corresponding knitting machine.

It is advantageous to adjust the pump pressure during a single lubrication pulse independently of the specific construction of the pump device, distributor device and connecting pipe and of the number of connected lubrication points. If a stepper motor is used as the drive for the pump, its individual steps can be converted into micropump pulses, the sequence of which forms a lubricating pulse. The spacing between individual micropump pulses is preferably designed such that the pressure in the tube does not fall below a minimum limit. This minimum pressure is preferably slightly lower than the injection pressure required by the attached nozzle. Under the action of prestress, the pipeline can meet the required injection pressure by keeping certain softness (elasticity). So that particularly small amounts of lubricant can be metered or the lubrication process can be prolonged over time.

Drawings

Various details of other advantageous forms of construction of the invention can be gathered from the embodiments of the invention shown in the drawings.

FIG. 1 is a schematic perspective view of a lubrication apparatus;

FIG. 2 is a sectional view of a section of the lubricating apparatus of FIG. 1 and shown in different proportions;

FIG. 3 is a horizontal cross-sectional view of a pump unit and a control unit of the lubricating apparatus;

FIG. 4 belongs to a horizontal cross-sectional view of a transmission of the lubricating apparatus of FIG. 2;

FIG. 5 is a top plan view of a ratchet wheel of the transmission of FIG. 4;

FIG. 6 is a horizontal cross-sectional view of a coupling device of the transmission of FIG. 4;

FIG. 7 belongs to a pump device of the lubricating apparatus of FIG. 2 and to a coupling device, ratchet and a threaded element for generating a linear movement;

fig. 8 is a graph showing the time change of the injection pressure of the oil flow flowing into one nozzle and the injection pressure of the oil flow flowing out of the nozzle;

FIG. 9 is a schematic plan view of a variant of the locking mechanism with a ratchet wheel embodied as a ratchet wheel;

fig. 10 is a schematic plan view of another variant of the locking mechanism with a ratchet wheel embodied as a ratchet wheel.

Detailed Description

Fig. 1 shows a lubricating apparatus 1 having a reservoir 2 for a lubricant, such as oil. In the lubricant reservoir 2, a distributor and pump unit 3 is inserted, which delivers a predetermined quantity of lubricant at a predetermined point in time via a set of lubricant lines 5a to 51 leading out.

The pump and dispensing unit 3 unit shown schematically in fig. 1 is shown in fig. 2. A piston pump 7, which is simultaneously a pump device 7a and a distribution device 7b, is used to deliver and distribute the lubricant. As shown in fig. 3 and 7, the piston pump 7 has a cylinder 8 with a cylindrical through hole 9. The through hole 9 forms a stepped bore at the lower end as shown in fig. 2 and 7, i.e. it has a section 10 of enlarged diameter. This section is intended for mounting a non-return valve 12, the valve body 14 of which can be screwed, for example, into a corresponding thread of the section 10.

The valve body 14 is provided with a passage 15 for mounting a valve blocking member 16. The head of the valve blocking element 16 is directed towards the inner cavity of the cylinder 8 defined by the through hole 9. If necessary, a spring, not shown in the figures, can tension the valve blocking element against a valve seat formed on the valve body 14.

The valve body 14 is provided with a plurality of radial bores, in this case for example 12 radial bores 17(17a to 171; fig. 3), which are arranged in a common plane 18 perpendicular to the through-opening 9, the radial bores 17a to 171 being arranged at the same angular distance from one another, while the distance between the radial bore 171 and the radial bore 17a is slightly greater than the same distance between the radial bores 17a to 171. Non-return valves, not shown in the figures, are inserted in the radial holes 17 (the reference numbers without letters indicate that all the radial holes 17a to 171 are identical), which allow the oil flow to flow radially inwards and outwards, i.e. from the through holes 9, outwards through the discharge channel constituted by the respective radial holes 17, but without being able to flow back.

The lubricant pipes 5a to 51 leading to the lubrication points are connected to the discharge valve. If necessary, the non-return valves can also be provided with corresponding lines 5a to 51 at the end remote from the distributor device 7b, in which case only one pipe connection is screwed in each case in the radial bores 17.

A piston 21 is inserted into the through-opening 9, the outer diameter of which piston substantially corresponds to the inner diameter of the through-opening 9. The piston is therefore axially displaceable and rotatable in the through-bore 9, but it defines a working space 22 (fig. 2) rather closely with the through-bore. The piston 21 has, in addition to its cylindrical circumferential surface 23, a relatively flat end face 24. A control groove 25 extends through the circumferential surface from the end face 24 parallel to its central axis 26. The length of the control slot 25 is preferably equal to or slightly greater than the distance of the flat surface 18 from the "top" dead centre 27 of the piston, shown in broken lines in figure 2. When the working space 22 is at its smallest, i.e. the piston 21 is in its lowermost position in fig. 2, the piston 21 reaches its top dead center 27 with its end face 24.

As shown in fig. 3, the control groove 25 is rather narrow and extends over a circumferential extent in the circumferential direction of the circumferential surface 23, which circumferential extent substantially corresponds to the diameter of the radial hole 17 in the wall of the through-hole 9. The depth of the control groove 25 is designed such that the flow resistance in the control groove 25 is not significantly greater than the flow resistance in the radial bore 17.

The piston 21 is inserted into a connecting sleeve 29 at its end projecting from the cylinder 8 and is connected thereto by a pin 30. The coupling sleeve 29 is also connected via a further pin 31 to an operating lever 32 which leads to a gear 33. The actuating lever 32 is rotationally fixed and is connected axially to a coupling half 34 which has two ribs 35, 36 extending axially and arranged parallel and at a distance from one another. Between which windows 37, 38 are formed, as shown in fig. 6.

The coupling half 34 belongs to a coupling device 39, the other coupling half 40 of which is formed by a radial pin 42 driven by a shaft 41. The pin engages with its two ends in the windows 37, 38 and can be brought into contact with a side of the ribs 35, 36, respectively, after a certain rotational play, here defined by 90 °.

Furthermore, as is apparent from fig. 7, the shaft 41 has a sleeve 43 which is connected to the radial pin 42 and is provided on its outside with a threaded element 44 having a plurality of external threads. The pitch is designed such that a 90 ° stroke of the axial female thread element 44 over the circumference corresponds to one complete piston stroke of the piston 21.

The threaded element 44 is operatively connected to another threaded element 45, which, as can be seen clearly in fig. 5, forms a ring element or segment supported by the ribs 35, 36 of the coupling halves 34. Thus, the one coupling half 34 changes its axial position relative to the other coupling half 40 while passing through the rotational clearance of the coupling 39.

The half-coupling 34 is provided with a section of internal thread (threaded element 45) constituting, on the outside thereof, a ratchet 46. The axially extending cross-section of the ratchet has generally trapezoidal teeth 47 which stop rotation of the coupling halves 34 but are axially movable. This is apparent from fig. 4. A movable lock lever 48 is supported radially inwardly of the ratchet 46. The locking lever 48 is pretensioned by a compression spring 49 towards its radially outer position in which it is not engaged with the ratchet 46. A lifting magnet 51 engages the locking lever 48 with its armature 52 via a corresponding lever 53 with the ratchet 46, so that the rotation of the ratchet is stopped by the teeth 47 in the given blocking position. These stop or locking positions correspond to the rotational positions of the control slot 25 (fig. 3) in alignment with one of the radial bores 17, respectively. There are accordingly 13 tooth gaps, of which 12 correspond to the position of the radial holes 17 and 13 th tooth gap corresponds to the larger gap between the radial holes 171 and 17 a. The size of the tooth gap corresponds to the distance of the radial bores 17.

The coupling half 40 is connected in a rotationally fixed manner to a shaft 41 which forms the output shaft of the stepping motor 55. The stepping motor is arranged coaxially with the operating lever 32 and is supported on a support 56. Furthermore, a multi-part holder 56 supports the lifting magnet 51 and has an annular, continuously smaller extension 57 arranged coaxially with the actuating rod 32, which extension supports the pump unit 7 at its lower free end. The extension has a flange-like extension 58, to which the lubricant tube 5 can be attached, and a microfiltration screen 59, which is pot-shaped and surrounds the lower end of the extension 57. Therefore, lubricant flowing into the inlet valve 12 must pass through the micro-sieve 59 in order to be filtered.

The coupling half 34 has a sleeve 60 with an external thread 61 on its side facing the operating lever 32. An axially polarized annular permanent magnet 62, shown separately in fig. 7, is secured to the sleeve 60 by a nut 63 provided with external threads 61. The permanent magnet 62 generates a force with its magnetic field, which force keeps the threaded element 44 in a play-free engagement with the thread 45. The purpose of this is to avoid undesirable idle running in the transmission mechanism, which is formed by the threaded element 44 and the internal thread 45 and which converts a rotary motion into a linear motion, when the stepping motor 55 rotates in the reverse direction.

The actuating lever 32 is supported in a sleeve 65 of the extension 57, which is arranged in a corresponding partition of the extension 57 in the vicinity of the connecting sleeve 29. The sleeve 65 allows for rotational and axial movement of the lever 32.

In order to monitor the movement of the piston 29, a magnetic sensor, for example a hall sensor 66, is arranged on the inside of the extension 57 adjacent to the permanent magnet 62, which sensor detects the position of the permanent magnet 62 and at least identifies the exceeding or not exceeding of the switch position. In order to detect the position of the transverse pin 42, a further hall sensor or a separate position sensor 67 can be provided, if necessary, in the vicinity thereof. The hall sensors 66, 67, the stepping motor 55 and the lifting magnet 51 are connected to a control unit which controls the lubricating apparatus 1 in the following manner:

to describe the sequential operation, assuming that piston 21 is first in the position shown in FIG. 3 and locking lever 48 is engaged with ratchet 46 due to the control of attracting magnet 51 (FIG. 4) assuming the threads of threaded member 44 are right-hand threads, stepper motor 55 is rotated to rotate cross-lock 42 in a clockwise direction, at least when cross-pin 42 is not yet in the solid line position of FIG. 6. For example, the transverse pin is rotated from the position shown by the broken line in fig. 6 to the position shown by the solid line. On turning this stroke, the threaded element 44 fixed axially inwards raises the coupling halves 34 axially, so that the piston 21 completes a suction movement. The working space 22 is enlarged and lubricant, such as oil, flows into the working space 22 through the inlet valve 12.

Wherein the ratchet 46 remains rotationally fixed. At the latest when the transverse pin 42 turns the ribs 35, 36, the stepping motor 55 stops. At this time, the attracting magnet 51 is deenergized, and the ratchet 46 is released. The stepper motor 55, which has thus far caused a reciprocating movement of the piston 21, now moves the ratchet 46, which is now freely rotatable, forward by one tooth position. In which the cross pin 42 carries the ribs 35, 36 and therefore the half-coupling 34, so as to turn the control slot 25 in line with the radial hole 17 a. When this position is reached, the attracting magnet 51 is re-energized, thereby pressing the locking lever 48 into the corresponding tooth gap of the ratchet 46. Whereupon the ratchet again remains torsionally stiff.

In order to dispense the required amount of lubricant to the lubricant tube 5a, the stepper motor 55 is now controlled in a counter-clockwise direction. Due to the size of the windows 37, 38, the rotational movement is limited to a quarter turn here. When the stepping motor 55 is turned this stroke, this rotational movement is converted by the mutual movement of the threaded element 44 and the internal thread 45 into a downward-acting axial movement of the coupling half 34 as shown in fig. 2. In which the piston 21 is moved by the operating rod 32 in the direction of its top dead center 27 without rotating downwards. The oil is distributed to the lubricant pipe 5a accordingly. Wherein the entire stroke need not be traversed. The stepper motor 55 may be stopped before the stepper motor has passed a quarter turn. In this case, a correspondingly smaller amount of oil is dispensed, so that the amount of oil to be dispensed can be precisely metered.

After the downward movement of the piston 21 is completed, the stepping motor 55 is operated again in the clockwise direction until the crossbar 42 reaches the ribs 35, 36 again. The attracting magnet 51 is now released so that the compression spring 49 pushes the lock lever 48 radially outward and releases the ratchet 46. The stepper motor now rotates one tooth forward (several teeth if desired) with the coupler halves 34 and piston 21 rotating to control the next lubrication position. For example, the control slot 25 now turns to coincide with the radial hole 17 b. The cycle described in connection with the radial holes 17a is repeated here to begin. It is thus possible to control all the radial bores 17 one after the other and to supply the appropriate amount of oil individually to all the lubricant ducts 5.

As shown in fig. 8, a pulse-like oil supply is possible. The injection pressure P generated by the pump device 7a can be set within a lubrication interval t1, t 2. For this reason, the stepping motor 55 performs stepping control and movement, and therefore the piston 21 also performs stepping movement. In the short rest intervals, the pressure P may each fall slightly below the pressure limit P1. At pressure limit P1, the connected nozzle starts injecting oil. The nozzle injects the fuel intermittently when the pressure value drops below the limit value, for example, respectively to a slightly lower pressure value P0. Thereby causing the flow of oil V1 to the nozzle to fluctuate and the fluctuations are temporary due to the elasticity of the oil pipe. The oil flow V2 from the nozzle is in the form of droplets, so the oil flow between individual oil drops due to a short pressure drop is zero. Thus, even a small amount of oil can be ejected for a long time with a relatively large nozzle that is not easily clogged.

When the lubricating device 1 is put into operation, the pump device 7a first needs to be evacuated. For this purpose, the piston 21 is turned to the exhaust position in which its control groove 25 coincides with the radial hole 17L, which is open to the outside and in which no non-return valve is arranged. One or more complete piston strokes are required to displace the air and fill the pump volume with lubricant. Then, normal operation can be performed.

Fig. 9 shows a variant of the locking mechanism. The ratchet 46 here constitutes a ratchet wheel. The lock lever 48 constitutes a latch claw. This eliminates the need for an attracting magnet to control each rotation of the ratchet 46. The lock lever 48 spring loads the ratchet 46. It causes the ratchet 46 to rotate one revolution in a clockwise direction (arrow 70) thereby rotating the piston 21 and operating the dispenser. But rotation in the counterclockwise direction (arrow 71) is prevented so that the pumping process can take place. The movement of the lifting magnet 51 is only required in exceptional cases of pole-to-pole.

Fig. 10 shows a further modified embodiment. The teeth of the ratchet 46 have teeth 47 with a relatively small flank steepness. The locking lever 48 constitutes a radially inner spring-loaded detent. In this embodiment, the rotational movement of the piston 21 is controlled in such a way that after the coupling device 39 has passed through the rotational gap, the stepping motor 55 is rotated to the right or left against the braking torque of the locking lever.

In particular in lubricating apparatuses with multiple lubricating points for feeding lubricant to a knitting machine, a pump device 7a is provided which simultaneously serves as a distributor device 7 b. For this purpose, the pump device 7a has a piston 21 with a control groove 25. The respective pump cylinder has an inlet and a plurality of outlets distributed over the cylinder wall. A corresponding lubrication point is selected depending on which outlet the control groove 25 of the piston 21 is turned into correspondence with. The pump means 7 is at the same time a dispensing means.

Claims (12)

1. Lubricating device (1) with multiple lubricating points comprising:

a pump device (7a) for delivering lubricant to said lubrication points,

a distribution device (7b) for distributing the lubricating portion to one of the multiple lubricating points, wherein the pump device (7a) has a piston (21) which is mounted in a cylinder (8) so as to be axially movable;

characterized in that, for forming the distribution means (7b), discharge channels (17) are provided in the cylindrical cylinder wall of the cylinder (8) of the pump means (7a), which discharge channels are connected to one of said multiple lubricating points via a respective pipe (5), at least one control groove (25) is provided in the circumferential surface (23) of the piston (21) of the pump means (7a), said control groove (25) being selectively aligned with at least one discharge channel by rotation of the piston (21), so that the selected discharge channel is connected to the working space (22) in the cylinder (8) of the pump means (7a), a transmission means (33) is provided for axial displacement of the piston for pumping movement of lubricant to the lubricating points and for rotational movement of the piston (21) for selection of the discharge channel, which transmission means has a stepping motor (55), the stepping motor is rotationally driven to select the discharge channel (17) when being connected with the piston (21) in a rotationally fixed manner via a coupling device (39), and the piston (21) is axially moved via a transmission mechanism when the rotationally fixed connection is released by the coupling device (39) and the piston is locked in rotation by a locking device (46, 48), the transmission mechanism converting the rotational movement of the stepping motor (55) into a linear movement.

2. Lubricating apparatus according to claim 1, characterised in that the coupling means (39) has a defined rotational clearance.

3. Lubricating apparatus according to claim 1, characterised in that the retaining means (46, 48) has a retaining element (48) which can be brought into and out of engagement with a ratchet wheel (46) which is connected in a rotationally fixed manner to the piston (21).

4. Lubrication apparatus according to claim 3 characterised in that the stop element (48) engages and disengages the ratchet wheel (46) by means of a servo drive (51).

5. Lubricating apparatus according to claim 1, characterised in that the ratchet wheel (46) is formed as a counter wheel and the stop element (48) is formed as a stop pawl.

6. The lubrication system as set forth in claim 1, wherein: two screw elements (44, 45) belong to the transmission mechanism, wherein one screw element is connected with the piston (21) in a non-rotating way, and the other screw element is connected with the rotating device (55) in a non-rotating way.

7. Lubrication apparatus according to claim 6, characterised in that at least one screw element (44) is connected to a magnet (62) for tensioning the screw elements (44) against each other.

8. Lubricating apparatus according to claim 1, characterised in that a control device is provided, by means of which the stroke of the piston (21) can be determined.

9. Lubricating apparatus according to claim 1, characterised in that an inlet passage (12) leading into the cylinder (8) and an outlet passage (17) connected to the pipe (5) are each provided with a non-return valve.

10. Lubrication apparatus according to claim 1 characterised in that a sensor means (66) is provided to monitor the movement of the piston (21).

11. Method for lubricating multiple lubrication points of a machine by means of at least one pump device via a plurality of pipes, wherein lubricant is fed from the pump device via a selected pipe to one or more selected lubrication points, characterized in that the injection pressure (P) established by the pump device is adjusted in a pulsed manner within a lubrication interval (t1, t2), for which purpose the piston of the pump device is driven stepwise such that lubricant is intermittently injected from the nozzle to the selected lubrication point.

12. A method according to claim 11, characterized in that the lubrication process comprises a pressure pulse, which pressure pulse consists of a sequence of individual pulses, the pressure drop between the individual pulses not being allowed to fall below a minimum pressure level.