GB2058952A - A lubricating system for an internal combustion engine - Google Patents

Abstract

A lubrication system for supplying lubricating oil to a number of spatially distributed lubrication points in internal combustion engines comprises oil distribution units (OV1 to OVn) connected via feed pipes (9) to a main lubricating oil pipe (8) supplied with lubricating oil under variable pressure from a lubricating oil pressure generator (7). Lubrication pipes (PL1 to PLn) are connected to lubrication points (including SK) and are connected internally of the units to the respective feed pipes (9) via electrically controllable oil flow control elements which are connected to an electronic central control unit (10). Signals proportional to the speed of the engine are delivered to the control unit (10) and electrical pulses of a controlled duration may be delivered in a controlled sequence and at controlled times to the oil flow control elements in order to open the lubrication pipes (PL1 to PLn), such that exactly measured quantities of lubricating oil may be delivered to the individual lubrication points. Supply of lubricating oil may be automatically controlled in dependence upon the speed of the engine, and each quantity of lubricating oil may be adapted to the particular load in the required lubrication zone. <IMAGE>

Description

SPECIFICATION A lubricating system for an internal combustion engine This invention relates to a lubricating system for an internal combustion engine.

It is a particular, although not exclusive object of the present invention to provide such a lubricating system in which, depending on the speed of an engine, the places to be lubricated are supplied at a controlled time with lubricating oil in a controlled quantity, to ensure a locally exact supply of lubricating oil in a precisely defined region of the parts to be lubricated, in any speed range and under any load on the combustion engine. Such a lubricating system is intended to be significantly less expensive to produce than comparable, purely mechanically controlled lubricating systems.

More generally, according to the present invention, there is provided a lubrication system for supplying lubricant to a plurality of spatially distributed lubrication points in an internal combustion engine, the system comprising: a main lubricant duct; a plurality of lubrication ducts for connection to respective lubrication points; flow control means connected between said main lubricant duct and said lubrication ducts; electrical control means for actuating said flow control means; and an electronic control unit which is arranged to receive a signal dependent upon the speed of a respective engine, and to process said signal to produce at least one control signal for controlling the quantity of lubricant delivered to said lubrication points.

The lubricating system of preferred embodiments of the invention may provide an automatically controlled supply of lubricating oil, in dependence upon the speed of the respective engine, to each individual place to be lubricated at the correct time, for the requisite period and under the necessary pressure, such that each quantity of lubricating oil is adapted to a particular load in a required lubrication zone. By limiting mechanical components mainly to means for pressure generation and for opening and closing the lubrication ducts leading to the lubrication points, in conjunction with the use of an otherwise fully electronic control system, a considerably reduction in manufacturing costs in relation to comparable mechanically controlled lubricating systems may be achievable.In particular, if the components of the electronic control unit are mainly combined on a single circuit board to form a prefabricated slide-in module which, if necessary, may be replaced in its entirely, any fault occurring may rapidly be corrected because, in this event, the defective slide-in module need only be replaced by a new module.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings, in which: Figure 1 is a block diagram of the overall arrangement of a lubricating system according to a first embodiment of the invention; Figure 2 is a block diagram of the overall arrangement of a lubricating system according to a second embodiment of the invention; Figure 3 shows an arrangement of lubrication points on a cylinder; Figure 4 shows means for the control of the pressure generation of lubricating oil in the embodiment of Fig. 1; Figure 5 shows means for the control of the pressure generation of lubricating oil in the embodiment of Fig. 2; Figure 6 shows a first embodiment of an oil distribution system; Figure 7 shows a second embodiment of an oil distribution system;; Figure 8 shows a third embodiment of an oil distribution system; Figure 9 shows a first embodiment of a control circuit module for an oil distribution system of the type shown in Fig. 6; Figure 10 shows a second embodiment of a control circuit module for an oil distribution system of the type shown in Fig. 6; Figure 11 shows a third embodiment of a control circuit module for an oil distribution system of the type shown in Fig. 6; Figure 12 shows a first embodiment of a control circuit module for an oil distribution system of the type shown in Fig. 7; Figure 13 shows a second embodiment of a control circuit module for an oil distribution system of the type shown in Fig. 7; Figure 14 shows a third embodiment of a control circuit module for an oil distribution system of the type shown in Fig. 7;; Figure 15 shows details of a first timing element of the circuits shown in Figs. 10, 11, 13 and 14; and Figure 16 shows details of a second timing element of the circuits shown in Figs. 11 and 14.

In the Figures, identical or corresponding elements are denoted by the same reference numerals.

Figs. 1 and 2 each diagrammatically illustrate the overall arrangement of a lubricating system for a multi-cylinder internal combustion engine in this case a two-stroke internal combustion engine. The reference 1 denotes the crank shaft, the references Z1, Z2, Z3 to Zn denote the cylinders and the references K1, K2, K3 to Kn denote the associated pistons of the combustion engine. The pistons are coupled to the crank shaft 1 through piston rods 2 and drive rods 3 via crossheads 4 with a slide blocks supported on associated slide paths G. The reference 5 denotes a lubricating oil reservoir followed via a delivery pipe 6 by a lubricating oil pressure generator 7. A main lubricating oil duct or pipe 8 in the form of a high-pressure accumulator leads away from the pressure generator 7 on its output side.Feed ducts or pipes 9 branch off from the main lubricating oil pipe 8, an oil distribution system (or lubrication unit) OV1, OV2, OV3 to OVn being connected to each of these feed pipes 9. Each of these oil distribution systems is associated with a cylinder of the combustion engine to supply its lubrication points S1, S2 to Sn shown in detail in Fig. 3 and is connected to these lubrication points through associated lubrication ducts or pipes PL1, PL2 to PLn. In order to obtain as wide as possible a lubrication angle wetted with lubricating oil spray, the nozzles D of the individual lubrication points are advantageously directed substantially tangentially onto the cylinder wall.In addition, it is also possible-as shown in chain lines in Fig. 1-to supply lubrication points SK with lubricating oil at the crossheads 4 and their slide paths G from the connected oil distribution systems through corresponding lubrication pipes.

Each oil distribution system OV1 to OVn comprises electrically controlled oil throughflow control elements of which the electrical control lines-each combined in a control channel B1, B2 to Bn, lead to a novel electronic central control unit 10. This electronic central unit 10 contains all the switching elements required for controlling lubrication.

In the embodiment illustrated in Fig. 1, the electronic central control unit 10 incorporates a microprocessor 11 for controlling the release of lubricating oil to all individual lubrication pipes and for controlling other functions, such as that of the lubricating oil pressure generator 7, and also other switching elements such as amplifier circuits 1 2 for amplifying the control signals leaving the microprocessor 11. The microprocessor 11 consists of a central processor unit CPU, at least one read-only memory ROM as a fixed-value memory for user programmes, at least one read/write memory RAM as the working memory of the system, a clock generator 13, a. time base 14 and an additional logic unit 1 5 which is used for example for monitoring additional functions.The above-mentioned components of the microprocessor 11 are connected to a multi-wire central data distribution channel 1 6 common to all of them, a socalled data bus, to which on the other hand the control lines leading to the electrical components of the individual oil distribution systems and other connected components are also connected. These components also include a function generator 1 7 which is controlled by the crank shaft 1 and which is connected by a lead 1 8 to the data bus 1 6.

Thus function generator 1 7 delivers the angular positions of the crank shaft with a very high angular resolution in binary code to the microprocessor as control parameters. The resolution of one crank shaft revolution takes place in 29, i.e. 512 steps, and possibly even in 2'0, i.e. 1024 steps, thus providing a sufficiently accurate basis for exact lubricant control. Fig. 1 shows an analog function generator which gives off electrical voltages corresponding to the angular position of the crank shaft. These electrical voltages are converted in an analog-digital converter 1 9 arranged in the central control unit 10 into digital signals which are delivered via the data bus 1 6 to the microprocessor 11.

Instead of using an analog function generator, it is also possible to use a digital incremental crank angle pick-up which, for every revolution completed by the crank shaft, generates pulses corresponding to the number of divisions of the function generator, for example 1024. In this case, the analog-digital converter is unnecessary. The function generator 1 7 is arranged at a point of the crank shaft where very little, if any, torsional vibration occurs.

In addition, the electronic central control unit incorporates another analog-digital converter 20 which, at its digital output, is also connected to the data bus 16 and, at its analog input, to a pressure instrument transducer 21 which is built into the main lubrication pipe 8 to monitor the lubricating oil pressure. This pressure instrument transducer delivers digitalised pressure values via the analog-digital converter 21 to the microprocessor where they are processed by a program, in dependence upon the rotational speed signalled by the function generator 1 7.

If necessary, signals are delivered to the lubricating oil pressure generator 7 via channels 22 and 23 (Fig. 4) for the purpose of correspondingly re-adjusting the oil pressure.

As shown in Fig. 4, the lubricating oil pressure generator 7 consists of a high-pressure pump 24 which delivers lubricating oil from the oil reservoir 5 through the feed pipe 6 via a pressure-regulating valve 25 into the main lubricating oil pipe 8. The pressure regulating valve 25 is electrically adjustable by a servomotor 26 to which the microprocessor delivers signals for a direction of rotation with correspondingly higher pressure via the channel 22 and signals for a direction of rotation with correspondingly lower pressure via the channel 23. This guarantees that an oil pressure adapted to the speed of the engine or machine is permanently present in the individual oil distribution systems.

Three variants of the oil distribution systems OV1 to OVn are described in the following.

In the variant illustrated in Fig. 6, the oil throughflow control elements in an oil distribution system OV are formed by electrohy draulic servo valves SV1, SV2 to SVn. Each of these servo valves is connected at its input end to a feed pipe 9 and, at its output end, to one of the lubrication pipes PL1 to PLn. In addition, each of the servovalves SV1 to SVn is designed to receive control signals by which it is opened from the microprocessor 11 through a control line arranged in an associated control channel B.This embodiment of the oil distribution system may be used with advantage above all in cases where not only the lubrication points S1 to Sn on a cylinder, but also other moving parts in the vicinity of this cylinder of the combustion engine, for example as mentioned at the beginning-the crosshead 4 and its slide paths G, are to be supplied with lubricant because each servo valve SV1 to SVn is designed to be opened by electrical signals. This variant of the oil distribution system enables the user to establish virtually any control cycle per program in the microprocessor. Thus, it is possible for example to release those lubrication pipes PL1 to PLn connected to the lubrication points S1 to Sn of the cylinder individually one after the other or collectively at the same time in regular alternation by correspondingly activating the associated servo valves.In addition, it is possible to release those lubrication pipes which lead for example to the crosshead 4 and its slide path or to other lubrication points independently of the programmed release of the cylinder lubrication points S1 to Sn again per program in a suitable cycle. The particular program itself is established by correspondingly programming the read-only memory ROM and the read/write memory RAM of the microprocessor 11.

In the variant of an oil distribution system shown in Fig. 7, the oil throughflow control elements consists of a single electrohydraulic servo valve SV which installed in a feed line 9-precedes a rotatory electrohydraulic reversing switch 27. The reversing switch 27 consists of a housing 28 and of a distributor rotor 29 which is in turn coupled for adjustment to a servo motor 30 and which cooperates with a sensor 31 for sensing a switching position. An inflow reservoir 32 of the distributor rotor 29 is connected on the inflow side to the feed pipe 9 designed to be released by the servo valve SV and, on the outflow side, is connected through a distributor passage 33 in any residence position of the distributor rotor 29 to one of the lubrication pipes PL1 to PLn which open into the housing 28 and which are arranged at uniform angular intervals from one another.The servo valve SV, the servo motor 30 and the sensor 31 are each connected through a control line arranged in a control channel B to the data bus 1 6 of the microprocessor 11. These three components are controlled per program established in the read-only memory ROM and the read/write memory RAM of the microprocessor 11. To this end, corresponding electrical signals are initially delivered to the servo valve SV at a controled time and for a controlled period so that the servo valve SV opens and lubricating oil passes under corresponding pressure through the lubrication pipe selected by the distributor rotor to the associated lubrication point.One completion of this operation, the servo valve SV closes again, the servo motor 30 receives a control command whereby the distributor rotor 29 is turned until the reaching of the next switching position is signalled to the microprocessor by the sensor 31 where upon the control command for the servo motor is interrupted again, so that the distributor rotor-remaining in this residence position-is connected with its distribution passage to the next lubrication pipe.

This cycle is repeated for each lubricating operation. In the embodiment shown by way of example in Fig. 7, it is only possible to select one lubrication point at a time. However, if several lubrication points are to be supplied with lubricant at the same time, it is merely necessary in this case to use another distributor rotor 29 of which the distribution passage 33 would have to be modified or amplified accordingly, as shown in chain lines in Fig. 7. Through this measure, it would be possible for example simultaneously to supply two or even more of the lubrication points distributed around the circumference of a cylinder (see Fig. 3) with lubricating oil.

In the variant of an oil distribution system OV1 to OVn illustrated in Fig. 8, the oil throughflow control elements consist of a rotatory electrohydraulic reversing switch 34 with a housing 35 and a distributor rotor 36 which is adjustable by a servo motor 37 and which, in addition, cooperates with a sensor 38 for sensing its switching position. An inflow reservoir 39 of the distributor rotor 36 is connected on the inflow side to a feed pipe 9 and, on the outlfow side, to a distribution passage 40 within the distributor rotor. The lubrication pipes PL1 to PLn open into the housing 35, their inner openings being uniformly arranged around the periphery of the distributor rotor 36. In the drawing, the distributor rotor 36 with its distribution passage 40 is shown in an intermediate position between two lubrication pipe openings.These intermediate positions are denoted by the odd numbers 1, 3, 5, 7, 9 and 11, whilst the lubrication pipe openings are denoted by the even numbers 2, 4, 6, 8, 10 and 12. In the intermediate positions of the distributor rotor, the passage from the feed pipe 9 to the adjacent lubrication pipe is blocked. The sensor 38 and the servo motor 37 are each connected to the data bus 26 of the microprocessor 11 through control lines combined in a control channel B. The two components are controlled per program established in the read-only memory ROM and read/write mem ory RAM of the microprocessor 11.

For a lubricating operation, the servo motor 37 initially receives an instruction to turn the distributor rotor 36 from an intermediate position into the next lubricating position. When this next lubricating position is reached, the servo motor is stopped by a signal from the sensor 38 checked back by the microprocessor 11, the distributor passage 40 and a lubrication opening pipe now coming into alignment with one another so that the lubricating operation can take place. The residence time of the distributor rotor is controlled by program in dependence upon the speed of the engine or machine. At the end of each lubrication phase, the servo motor receives another instruction to turn the distributor rotor 36 into the next intermediate position, on reaching which the servo motor is stopped again by a signal from the sensor 38. This cycle is repeated for each lubricating operation.In this variant, too, it is normally only one lubrication point which has to be supplied with lubricating oil. However, by correspondingly widening or enlarging the distributor passage 40 in the distributor rotor (see dash-dot lines), two or even more lubrication points may be simultaneously supplied with lubricating oil in regular alternation with the others.

The function of this oil distribution system is described in the following in conjunction with the other elements of the lubrication system according to the invention as illustrated in Figs. 1, 3 and 4.

Each complete revolution of the crank shaft 1 is signalled to the microprocessor 11 by the function generator 1 7 which it controls in the form of 1024 pulses for a resolution of 210 steps Accordingly, since the movements of the pistons K1 to Kn of the internal combustion engine and hence of any other moving parts optionally to be lubricated are strictly dependent upon the movement of the crank shaft 1, certain very exact numbers of pulses based on the total number of 1024 function generator pulses per revolution of the crank shaft also have to be delivered to the individual lubrication points.Thus, for example, the travel of the piston beginning from the lower dead-centre position UT during the upward stroke to the upper dead-centre position OT resulting from half a revolution of the crank shaft is exactly represented by 51 2 function generator pulses, so that an exact number of pulses between 0 and 51 2 may be associated with each region of the piston stroke. Since, in addition, the lubrication points S1 to Sn (see Fig. 3) are fixedly arranged on the cylinder, for example in the upper third thereof, an injection of lubricating oil which begins exactly in space and time is possible between the first and second piston rings of a piston K1 to Kn by a corresponding delivery of pulses.These spatially fixed numbers of pulses are determined and stored in the microprocessor in the form of digitalised fixed values for each cylinder. The same applies to the lubrication points of the crossheads 4 and their guide paths G and to any other part to be lubricated. Since the hydraulic control elements generally respond with some delay after release by the electronic elements, the delay may actually be taken into account when the respective numbers of pulses are being established in the form of a lead of the electronic elements over the hydraulic elements. However, the necessary lead may also be calculated per program by the microprocessor 11 in dependence upon the angular speed of the crank shaft 1 as signalled by the function generator 17.In the same way as the beginning of a lubricating operation, the duration of a lubricating operation may be marked by numbers of pulses established in dependence upon distance, the difference between the upper and lower numbers of pulses corresponding to the distance travelled by a piston during the lubricating oil injection phase. On the other hand, the duration of a lubricating operation may also be calculated per individual program by the microprocessor 11 in dependence upon the rational speed or angular speed of the crank shaft 1 as signalled by the function generator 1 7. Yet another program determines the sequence in which the individual oil throughflow control elements are selected within the individual oil distribution systems OV1 to OVn.This program may be worked out in such a way that lubrication takes place during each piston stroke or only during every second or other piston stroke.

Another program determines the control of the lubricating oil pressure generator 7 (Fig.

4), by which its servo motor 26 is adapted to receive signals corresponding to an increase or reduction in the lubricating oil pressure again in dependence upon the rotational speed or angular speed as signalled by the function generator 1 7 giving rise to desired pressure values which can be calculated in the microprocessor 11. However, the servo motor 26 only receives a signal from the micropro- cessor when the calculated desired values do not coincide with the pressure values communicated by the pressure transducer 21 and digitalised in the analog-digital converter 20.

The individual programs are called up in the microprocessor by its central processing unit CPU, which is supplied by the clock generator with a clock frequency lying in the 100 KHz range, in accordance with the different priority allocated to it or, for the same priority, are boxed in one another in the same order in which they are called up or in a defined time slot pattern.

In the variant of a lubrication system illustrated in Fig. 2, the differences from the variant illustrated in Fig. 1 lie in a different structure of the electronic central control unit 10 with a different control mode and different electronic control means for generating the reference signals and for controlling the lubricating oil pressure generator and the oil throughflow control elements of the individual oil distribution systems OV1 to OVn. In this variant, the oil distribution systems have the same structure as i.n the variant shown in Fig.

1 and described with reference to Figs. 6, 7 and 8. The same applies to the connection of the lubricating pipes PL1 to PLn of the individual oil distribution systems OV1 to OVn to the associated lubrication points S1 to Sn on the particular cylinder, as described with reference to Fig. 3. In addition, the cylinders Z1 to Zn, the pistons K1 to Kn and their push rods 2 and drive rods 3 are constructed and arranged in the same way as in the corresponding elements shown in Fig. 1, except that in this case they are diagrammatically illustrated adjacent one another looking in the direction of the longitudinal axis of the crank shaft, whereas the cross heads 4 are in this case equipped with additional elements as will be described hereinafter.

As shown in Fig. 2, the central control unit 10 accommodates several identical control circuit modules SM1 to SMn, of which each is associated with one of the oil distribution systems OV1 to OVn for releasing its lubrication pipes PL1 to PLn leading to the lubrication points S1 to Sn on the particular cylinder. In addition, the central control unit 10 accommodates an additional control circuit module ZSM for controlling an additional oil distribution system ZOV, which is used for centrally supplying the lubrication points SK--connected to the lubrication pipes GS1 to GSn---on the slide paths of the individual crossheads, and a control circuit SP for the operation of the lubricating oil pressure generator 7.The lubricating oil pressure generator may consist of a constant high-pressure accumulator which is fed with lubricating oil from a reservoir 5 by a high-pressure pump in conjunction with the feed pipe 6 and to which the main lubricating oil pipe 8 is connected on its output side. In this case, the control circuit SP takes over control of the highpressure pump, monitoring of the pressure level and readjustment of the delivery rate in the event of any deviation from a preset level.

Fig. 5 shows a variant comprising a lubricating oil pressure generator 7 and a control circuit SP for generating a lubricating oil pressure in dependence upon the speed of the engine or machine. Like the lubricating oil pressure generator shown in Fig. 4, the lubricating oil pressure oil generator 7 shown in Fig. 5 consists of a high-pressure pump 24 which delivers lubricating oil from the reservoir 5 through the delivery pipe 6 to a pressure-regulating valve 25 and via this valve to the main lubricating oil pipe 8 in the form of a high-pressure accumulator. The pressureregulating valve 25 is adjustable by an electrical servo motor 26 of which the two control inputs are connected by control lines 41 and 42 to the control circuit SP where they are connected to the positive or negative output of a comparing operational amplifier 43.An adjustment angle pickup 44 is associated with the servo motor 26, the changes in its angle of rotation being proportional to the pressure changes. The adjustment angle pickup 44 is in turn connected to a transformer 45 which converts angles of rotation into proportional electrical voltages which are relayed to a negative input of the operational amplifier 43.

The positive input of the operational amplifier 43 is connected to a voltage transformer 46, which, at its input end, is connected by a control line 47 to a tacho-generator 48 (see Fig. 2). The tacho-generator 48 is driven by the crank shaft 1 and generates an a.c. voltage proportional to the rotational speed which is rectified and filtered in the voltage transformer 46. The d.c. voltage thus formed appears at the positive input of the operational amplifier 43. The voltage coming from the transformer 45 which is proportional to the angle of rotation of the servo motor is present at the negative input of the operational amplifier 43.

If the voltages at the two inputs are equal, the servo motor stops, so that a certain pressure is adjusted to a pressure regulating valve 25.

If the rotational speed of the crankshaft and, hence, the voltage at the positive input of the operational amplifier 43 increase, the operational amplifier reacts to the positive differential voltage between the two inputs and, through the pipe 41, gives the servo motor an instruction to rotate in the forward direction corresponding to an increase in pressure. The servo motor then rotates until the voltage proportional to the angle of rotation at the negative input of the operational amplifier 43 is equal in value to the voltage at the positive input.In the same way, a reduction in rotational speed is followed by a readjustment in the oil pressure, the negative differential voltage between the positive and negative inputs of the operational amplifier 43 being reduced to zero by a corresponding control command through the pipe 42 to the servo motor 26 to rotate backwards corresponding to a reduction in pressure. In this way, the lubricating oil pressure is optimally adapted to the speed of the machine or engine.

In order to obtain control signals dependent on distance and proportional to the speed of the engine or machine, each control circuit module SM1 to SMn of the electronic central control unit 10 is preceded by a control switch 49 which, in this case, is fixedly arranged on the slide path G for the associated crosshead 4, is controlled by a control line to the associated control circuit module and is designed to be operated by a release element 50 which is arranged to move past it and which is fixed to a moving part of the internal combustion engine, in this case to the crosshead 4.In the event of a relative movement between the control switch 49 and the release element 50, the switching path which is limited by the length L of the release element 50 directly marks the beginning, duration and end of activation of the associated control circuit module SM1 to SMn and hence the activation of the oil throughflow control elements of the associated oil distribution system OV1 to OVn connected thereto. In order to ensure that the control switch 49 does not actuate the connected control circuit module both during the upward stroke and also during the downward stroke of the associated piston, but only during the upward stroke thereof, the control switch 49 is respectively preceded and followed in the direction of movement of the release element 50 by direction control switches 51 and 52.Both direction control switches 51 and 52 are also designed to be activated by the release eie- ment 50 and are also connected by control lines to the associated control circuit module.

The position of the fixed control switch 49 in relation to the movable release element is selected in such a way that, after activation of the associated control circuit module, the beginning of lubrication comes immediately after the first piston ring in the intermediate space up to the second piston ring. The position of the two direction control switches 51 and 52 in the space between OT and UT is arbitrary.

However, it is advantageously selected in such a way that the additional control circuit module ZSM connected both to the direction control switches and also to the control switch 49 is only activated to release the oil throughflow control elements of the additional oil distribution system ZOV at those times when the lubrication points SK on the slide paths G are covered by the slide blocks of the associated crossheads 4 and their lubrication passages are released.

One possible embodiment of a control circuit module SM for controlling an oil distribution system OV of the type shown in Fif. 6 is illustrated in Fig. 9. The control circuit module consists of a flip-flop 53, in this case a so- called RS-flip-flop, an AND-gate 54 and a driving circuit 55. The first input of the ANDgate 54 is connected to the control switch 49 and its second input to the Q-output of the flip-flop 53. The set input S of the flip-flop 53 is connected to the direction control switch 51 whilst its reset input R is connected to the direction control switch 52.The output of the AND-gate 54 is connected by a lead to the driving circuit 55 which, in the present case, consists of a ring counter 56 with a number of counting stages corresponding to the number of servo valves SV1 to SVn of the connected oil distribution system OV, the outputs thereof being connected by an amplifier circuit 57 to the control lines leading to the individual servo valves.

The function of this control circuit module is described in the following. The starting position of the piston will be assumed to be at UT. During the upward stroke of the piston K, the release element 50 initially passes the direction control switch 51 so that the flip-flop 53 is set and a switching signal appears at the second input of the AND-gate 54. When the release element 50 passes the control switch 49, a switching signal is also present at the first input of the AND-gate 54, so that the AND-gate 54 is switched through and a signal appears at an output of the driving circuit 55, activating the connected servo valve and releasing the associated lubrication pipe. In the present case, the beginning, duration and end of this lubricating operation are determined by the switching edges and the length L of the release element 50.When the release element 50 also passes the other direction control switch 52 as the piston continues its upward stroke, a signal appears at the reset input of the flip-flop 53, resetting and thus blocking this flip-flop. The result of this is that, during the downward stroke of the piston K, no signal is able to pass through the AND-gate despite actuation of all three switches. The above-described cycle is repeated during each upward stroke of the piston so that the lubrication points S1 to Sn may be individually supplied with lubricating oil one after the otherHne per upwards stroke of the piston.

Where several lubrication points on a cylinder are to be simultaneously supplied with lubricating oil, several of the control lines leading to the servo valves of an oil distribution system have to be connected to an output of the driving circuit 55 of the control circuit module and the number of counting stages of the ring counter 57 has to be reduced accordingly.

Another embodiment of a control circuit module SM for controlling an oil distribution system of the type shown in Fig. 7 is illustrated in Fig. 1 2. The sole difference between this embodiment and the embodiment illustrated in Fig. 9 lies in the driving circuit 55.

In this case, the sole servo valve SV of the oil distribution system 0V shown in Fig. 7 is connected to the output of the AND-gate 54 through its control line, as is a servo motor driving stage through its input 58. The servo motor driving stage consists of a first pulse circuit 59 which is connected to the input 58 and essentially comprises two series-connected monostables. The output of the pulse circuit 59 is connected to the setting input S of 9 flip-flop 60, in this case an RS-flip-flop, of which the output Q is connected through an amplifier stage 61 to the control line leading to the servo motor 30 (Fig. 7). The sensor 31 of this oil distribution system is connected by its control line to a second pulse circuit 62, consisting essentially of a monostables within the servo motor driving stage.

The output of the pulse circuit 62 is connected to the reset input R of the flip-flop 60.

This control circuit module performs the following functions. The starting position of the piston will again be assumed to be at UT.

During the upward stroke of the piston K, the release element 50 initially passes the direction control switch 51, so that the flip-flop 53 is set and a signal appears at the second input of the AND-gate 54. As the release element 50 passes the control switch 49, a signal is also applied to the first input of the AND-gate 54, with the result that this AND-gate is switched through. The signal appearing at its output is delivered both to the servo valve SV of the connected oil distribution system (Fig.

7), thereby releasing the lubrication pipe, and also the first pulse circuit 59 by which a brief signal is applied with delay after the end of the switching-through of the AND-gate and, hence, after the end of a lubricating operation to the setting input S of the flip-flop which is thus switched through. The signal appearing at the output Q is amplified in the amplifier stage 61 and delivered to the servo motor 30 as a control command. The servo motor 30 then drives the distributor rotor 29 until its entry into the next switching position is signalled by the sensor 31, after which a brief pulse is applied by the second pulse circuit 62 to the reset input R of the flip-flop 60, blocking it and stopping the servo motor 30.

As the piston K continues its upward stroke, a signal appears at the reset input R of the fiipflop 53 when the release element 50 passes the direction control switch 52, with the result that the flip-flop 53 is also reset and blocked.

The result of this is that, during the downward stroke of the piston K, no signal is able to pass through the AND-gate despite actuation of all three switches. The above-described cycle is repeated during each upward stroke of the particular piston K so that---depending on the formation of the distribution passage in the distributor rotor 29, the lubrication points S1 to Sn (Fig. 3) are supplied with lubricating oil either individually one after the other (one per upward stroke of the piston) or several at a time per upward stroke of the piston.

In the variant of the control circuit module illustrated in Figs. 9 and 1 2 and described above, the duration of a lubricating operation is determined by the length L of the release element and the speed of the engine or machine. However, to avoid dependence on certain types of switch, Figs. 10 and 1 3 show two variants of a control circuit module SM in which the release element 50 only controls the beginning of a lubricating operation. The duration of a lubricating operation is controlled both in the variant shown in Fig. 10 and in the variant shown in Fig. 1 3 by an electronic timing element ZD-identical in both cases--incorporated in the control line leading from the control switch 49 to the first input of the AND-gate 54.This timing element ZD is connected at its time control input to the control line 47 which leads to the tachogenerator 48 (Fig. 2). In other respects, the variant shown in Fig. 10 is identical in structure with the variant shown in Fig. 9.

Similarly, the variant shown in Fig. 1 3 is identical in structure with the variant shown in Fig. 12.

The timing element ZD is shown in detail in Fig. 1 5. It consists of a pulse circuit 63 of which the input is connected to the control switch 49 and its output to the setting input S of a flip-flop 64, in this case an RS-flip-flop.

Its output Q is connected on the one hand to the first input of the AND-gate 54 and, on the other hand, to an integrator stage 65. Its output is in turn connected to the positive input of a comparing operational amplifier 66 of which the negative input is connected to the control line 47 from the tacho-generator 48. The output of the operational amplifier 66 is returned to the reset input R of the flip-flop 64.

This circuit arrangement is based on the following function. If the control switch 49 is actuated during the upward stroke of a piston K, a brief pulse is applied by the pulse circuit 63 to the setting input S of the flip-flop 64 so that this flip-flop is switched through and delivers a signal to the first input of the ANDgate 54. Since a signal-released by the direction control switch 51-is already present at the second input, the AND-gate 54 is switched through, so that the particular lubricating operation begins. At the same time, however, the connected integrator stage 65 also receives from the output Q of the flip-flop 64 a voltage signal which is processed therein to the extent that a uniformly increasing voltage appears at its output, its increase being determined in dependence upon the input voltage.This increasing voltage is fed into the operational amplifier 66 by which it is compared with the speed-proportional voltage produced by the tacho-generator 48 and fed in through the negative input. If the voltage coming from the integrator stage 65 exceeds the speed-proportional voltage, the operational amplifier 66 releases at its output a signal which passes to the reset input of the flip-flop 64 and moves it back into the blocked position, with the result that the AND-gate 54 is also blocked again and the lubricating operation is over. When the voltage at the input of the integrator stage 65 disappears, its output voltage returns to zero. The completion of the function within a cycle then takes place in exactly the same way as described above with reference to Figs. 9 and 1 2.

Since a lubricating operation always begins slightly later than required with increasing rotational speed and particularly in the high rotational speed range on account of the inertia of the hydraulic control elements in relation to the piston position, this problem may be solved by a control circuit module SM by which the beginning of a lubricating operation and also its duration may be controlled in dependence upon the speed of the engine or machine. Two variants of a control circuit module SM suitable for this purpose are shown in Figs. 11 and 14. The variant shown in Fig. 11 is used to control an oil distribution system of the type shown in Fig. 6 whilst the variant shown in Fig. 1 4 is used for controlling an oil distribution system of the type shown in Fig. 7.The sole difference between the variants shown in Figs. 11 and 14 and those illustrated in Figs. 10 and 1 3 lies in the fact that the timing element ZD in the control line from the control switch 49 to the first input of the AND-gate 54 is preceded by a timing element ZB for controlling the beginning of lubrication in dependence upon rotational speed.

Like the timing element ZD, this timing element ZB is connected to the control line 47 which in turn is connected to the tachogenerator 48 and shown in detail in Fig. 16.

In this variant, the control switch and the release element have to be spatially advanced to a slight extent in such a way that, in relation to the position of the piston, the signal from the control switch 49 appears somewhat earlier than in the variants shown in Figs. 9, 10, 12 and 13. When the crankshaft is rotating at a low speed, the delay between the veginning of the signal from the control switch 49 and the beginning of the signal releasing the lubricating operation must be greater than at high rotational speeds.

The timing element ZB comprises a flip-flop 67, in this case an RS-flip-flop, of which the input S is connected to the control switch 49.

The output Q of the flip-flop 67 is connected on the one hand to the first input 68 of an electronic reversing switch 69 and, on the other hand, to a pulse circuit 70. Its output is in turn connected to the input of the pulse circuit 63 of the timing element ZD (Fig. 15).

The second input of the reversing switch 69 is connected to the control line 47 which leads to the tacho-generator 48. The output of the reversing switch 69 is connected to an integrator stage 71 which, at its output end, is connected to a comparator 72 of which the output is connected to the reset input R of the flip-flop 67.

The function of this circuit is described in the following. When the control switch 49 is actuated by the release element 50, a signal is applied to the setting input S of the flip-flop 64 so that this flip-flop 64 is set and a signal appears at the output 0 which, on the one hand, prepares the pulse circuit 70 and, on the other hand, actuates the normally open reversing switch 69.

As a result, the signal path from the tachogenerator 48 to the integrator stage 71 is opened so that a speed-proportional voltage is delivered to the integrator stage 71. The result of this is that, at the output of the integrator stage 71, the voltage increases linearly from zero, the steepness of the rise depending upon the input voltage. A high input voltagc corresponding to a high rotational speed-produced a steep increase, whereas a low input voltage-corresponding to a low rotational speed-produces a gentle increase. This voltage is compared with a fixed voltage value in the comparator 72.At the moment when the input voltage exceeds this fixed voltage value, the comparator 72 delivers a signal to the reset input R of the flip-flop 67 so that this flip-flop 67 returns to its blocked state. The period for which the flip-flop 67 is switched through is inversely proportional to the steepness of the increase in the voltage leaving the integrator stage 71.

The return of the flip-flop 67 to its blocked state causes the reversing switch 69 to open so that the output voltage of the integrator stage 71 again returns to zero and, in addition, the pulse circuit 70 is switched through and a brief signal is applied to the input of the pulse circuit 63 of the timing element ZD.

This signal marks the beginning of a lubricating operation of which the duration is determined by the timing element ZD and takes place in the same way as described above.

The control switches 49 and the two direction control switches 51, 52 with the release element 50 may be formed both by mechanical switches and by contactless magnetic or optical capacitive switches providing they satisfy the requirements imposed in regard to accuracy with respect to time, high switching speed, long useful life and high immunity to disturbance. It remains to be pointed out that these switches 49, 51 and 52, including the release element 50, do not necessarily have to be arranged on the slide path G of a crosshead 4 or on the crosshead itself, instead they may be arranged at any other suitable place in the internal combustion engine. In addition, it is also possible--since the movement of the piston is strictly dependent upon the movement of the crankshaft-to use a central pulse control system controlled by the crankshaft 1 for controlling the delivery of pulses to the individual control circuit modules, thus enabling outlay on individual switches to be reached.

The control circuit module ZSM provided in addition to the other control circuit modules SM1 to SMn for lubricating the crosshead may be constructed in the same way-in regard to its driving circuit as in the variants illustrated in Figs. 9 to 14. The same applies to the oil distribution system connected thereto. In the interests of simplicity, the switches 49,51 and 52 and the release element 50 of a cylinder Z are used for controlling the additional control circuit module ZSM and signals are derived from their leads to the connected control circuit module via branches 73 coupled thereto (see Fig. 2).Signals coming from the direction control switch 51 are used for controlling the lubrication points SK arranged at the lower end of the slide paths whilst signals coming from the direction control switch 52 are used for controlling the lubrication points arranged at the upper end of the slide paths G. Signals coming from the control switch 49 are used for preparing a lubricating operation.

All the switching elements of the electronic central control unit 10 are with advantage mainly arranged on a single circuit board. This circuit board is provided around its circumference with a plug of sliding contacts and, together with the electronic circuit elements arranged on it, forms a pre-fabricatable slidein module which may be inserted into correspondingly designed switch boxes (not shown) and which may be replaced in its entirety as and when required, for example in the event of a fault. In the switch box, all the control lines connected to the individual elements to be controlled are connected to corresponding connecting elements which are in electrical contact with the plug or sliding contacts of the circuit board in its inserted position.

Claims (31)

1. A lubrication system for supplying lubricant to a plurality of spatially distributed lubrication points in an internal combustion engine, the system comprising: a main lubricant duct; a plurality of lubrication ducts for connection to respective lubrication points; flow control means connected between said main lubricant duct and said lubrication ducts; electrical control means for actuating said flow control means; and an electronic control unit which is arranged to receive a signal dependent upon the speed of a respective engine, and to process said signal to produce at least one control signal for controlling the quantity of lubricant delivered to said lubrication points.

2. A system according to claim 1, wherein the electronic control unit is arranged to deliver control signals to said electrical control means for controlling the opening instants of said flow control.

3. A system according to claim 1 or 2, wherein the electronic control unit is arranged to deliver control signals to said electrical control means for controlling the opening durations of said flow control means.

4. A system according to claim 1, 2 or 3, wherein the electronic control unit is arranged to deliver control signals to said electrical control means for controlling the opening sequence of said flow control means.

5. A system according to any preceding claim, wherein the electronic control unit is arranged to deliver a control signal for controlling operation of a variable pressure generator for delivering lubricant under pressure to said main lubricant duct.

6. A system according to claim 5, including said generator.

7. A system according to any preceding claim, wherein said at least one control signal is a pulsed signal.

8. A system according to any preceding claim, wherein a plurality of feed ducts branch from said main lubricant duct, said flow control means being connected between said feed ducts and said lubrication ducts.

9. A system according to any preceding claim, wherein the flow control means comprises a plurality of electrohydraulic servo valves, each of which is connected at an input thereof to receive lubricant from said main lubricant duct, at an output thereof to a respective one of said lubrication ducts, and, through an electronic control line, to the electronic control unit.

10. A system according to any one of the preceding claims, wherein said flow control means comprises an electrohydraulic servo valve, a following rotatory electrohydraulic reversing switch having a housing and a distributor rotor, and an associated servo drive motor and sensor for sensing a switching position; the servo valve, the servo motor and the sensor are each connected through an electronic control line to the electronic control unit; and the distributor rotor comprises a supply reservoir which, on its inflow side, is arranged to be supplied via the servo valve with lubricant from said main duct, and which is connected to a distribution passage inside the rotor which, in one or more positions of the distributor rotor, is connected to one or more of said lubrication ducts, opening into said housing.

11. A system according to claim 10, wherein said positions of the distributor rotor are positions between which the rotor occupies intermediate positions in which said reservoir is not connected to any of said lubrication ducts.

1 2. A system according to any one of the preceding claims, wherein the electronic control unit comprises a microprocessor and amplifiers for amplifying signals leaving the microprocessor.

1 3. A system according to claim 5, wherein the microprocessor comprises a central processing unit, at least one read-only memory as a fixed-value memory for user programs, at least one read-write memory as a working memory, a clock, and a time base, which components are connected to a common data bus to which are also connected control lines leading to said electrical control means a digital incremental or analog function generator which is arranged to be driven by the crankshaft of a respective engine to emit a speed dependent signal.

1 4. A system according to claim 13, wherein the microprocessor includes an additional logic unit.

15. A system according to claim 13 or 14, wherein the function generator is of analog type, and is followed by an analog-digital converter.

1 6. A system according to any preceding claim, comprising a fixedly arranged control switch and a release element which is arranged, in use, on a moving part of a respective engine, to move past and thereby activate said control switch, to which the electronic control unit responds.

17. A system according to claim 16, wherein the electronic control unit responds to the switching action of the control switch, which action is in turn limited by the length of the release element, to determine directly the beginning and duration of a respective control signal to control the beginning and duration of a lubricating operation.

1 8. A system according to claim 1 6 or 17, wherein the control switch is preceded and followed in the direction of movement of the release element by respective direction control switches, both of which are also designed to be activated by the release element and are connected through control lines to the electronic control unit, which is arranged to respond in only one direction of relative movement between the control switch and the release element.

1 9. A system according to claim 18, wherein the electronic control unit comprises a flip-flop and an AND-gate, of which a first input is connected to the control switch and a second input to an output of the flip-flop, the set input of the flip-flop being connected to one of the direction control switches and the reset input of the flip-flop being connected to the other direction control switch, and said at least one control signal is derived, in use, from the output of the AND gate.

20. A lubrication system according to claim 19, comprising a ring counter driven by the AND-gate, the output of the ring counter being operable to control lubricant flow cyclically through said lubrication ducts.

21. A system according to claim 16 or to claim 18, 1 9 or 20 as appendant thereto, wherein the electronic control unit comprises timing means connected receive a signal from a tacho-generator which is arranged to be driven by the crankshaft of a respective engine, the timing means being used to control the duration of a flow of lubricant through a respective one of the lubrication ducts, in dependence upon the rotational speed of the engine.

22. A system, according to claim 21, wherein the electronic control unit comprises a further timing means arranged to receive a signal from the tacho-generator, and being used to control a delayed start of a flow of lubricant through a respective one of the lubrication ducts, in dependence upon the rotational speed of the engine.

23. A system according to claim 21 or 22, wherein the first-mentioned and/or further timing means includes an integrator.

24. A system according to at least claim 6, wherein said generator comprises a highpressure pump, a pressure-regulating valve, a servo motor driving the valve and an angle-ofrotation transducer, the electronic control unit being connected to receive a signal from a tacho-generator which is arranged to be driven by the crankshaft of a respective engine, and the electronic control unit being arranged to control the lubricant pressure in the generator, in dependence upon the rotational speed of the engine.

25. A system according to any preceding claim, wherein at least a greater part of the electronic central control unit is disposed on a single circuit board to form a slide-in module which is designed to be inserted into a switch box and to be replaced in its entirety as and when required.

26. A system according to any preceding claim, having a plurality of lubrication units for association with different cylinders and/or different parts of an engine, wherein the electronic control unit controls all of the lubrication units by a central processing unit.

27. A system according to any one of claims 1 to 25, having a plurality of lubrication units for association with different cylinders and/or different parts of an engine, wherein the electronic control unit has a plurality of control modules for controlling the respective lubrication units.

28. A lubrication system substantially as hereinbefore described with reference to Fig.

1 of the accompanying drawings.

29. A lubrication system substantially as hereinbefore described with reference to Fig.

2 of the accompanying drawings.

30. A lubrication system substantially as hereinbefore described with reference to Fig.

1 or 2, together with one or more of Figs. 3 to 1 6 of the accompanying drawings.

31. An internal combustion engine having a lubrication system according to any preceding claim.