GB2095003A

GB2095003A - Electronically controlled separate type fuel injection apparatus

Info

Publication number: GB2095003A
Application number: GB8204806A
Authority: GB
Original assignee: Diesel Kiki Co Ltd
Current assignee: Bosch Corp
Priority date: 1981-03-04
Filing date: 1982-02-18
Publication date: 1982-09-22
Also published as: JPS57146032A; JPH0118254B2; GB2095003B; DE3207808A1; DE3207808C2

Abstract

In an electronically controlled separate type fuel injection apparatus having a dual plunger for adjusting the amount of fuel injected and the injection advance, the positions of adjusting members forming the dual plunger are separately positioned by actuators 8, 9 in accordance with electric control signals which are produced from computing circuits 54, 55. As shown, the actuator 8, controlling the amount of fuel supplied, is energised by a signal derived from the difference between a desired speed set at 51 and the actual engine speed detected at 52 and the actuator 9 controlling the timing of the fuel injection is energised by the signal from computing circuit 55. <IMAGE>

Description

SPECIFICATION Electronically controlled separate type fuel injection apparatus The present invention relates to an electronically controlled separate type fuel injection apparatus.

In general, it is desirable for the timing of fuel injection of a fuel injection pump for a diesel engine to be adjustable so that the timing can be regulated to lower the fuel consumption of the engine, reduce the amount of harmful components in the exhaust gas and adapt the engine to various kinds of fuels. The timing of fuel injection of the fuel injection pump may be varied by changing the phase relation between the drive shaft and the cam-shaft of the fuel injection pump. In the conventional separate type fuel injection pump used in marine engine systems, however, the fuel injection pump is driven by a cam shaft provided on the side of the engine on which the fuel injection pump is mounted. This makes it difficult to control the injection system only by adjustment on the side of the injection pump without resorting to an arrangement having a complicated structure.

Accordingly, adjustable injection timing has never been provided on this kind of the injection pump.

Therefore, there has recently been proposed a separate type fuel injection pump employing a coaxial-type dual plunger mechanism having not only an adjusting rack for adjusting the timing of fuel injected but an adjusting rack for adjusting the timing of fuel injected so as to enable regulation of the injection timing. However, this recently proposed injection pump has a disadvantage in that whén the position of the rack for adjusting the timing of fuel injection is changed, the amount of fuel injected is also varied. This change in the amount of fuel injected changes the engine speed.

Although the change in the engine speed can be corrected by a governor, the separate type fuel injection pump used in a marine engine system is often operated at full regulation capacity of the governor, so that an insufficiency in the capacity of the governor will occasionally make correction impossible, or a change in the amount of fuel injected during full load operation will cause excessive output or insufficient output from the engine. As a result, in the today's separate type fuel injection pump, the timing of fuel injection and the amount of fuel injected cannot be controlled independently of each other and satisfactory performance characteristics cannot be obtained.

It is, therefore, an object of the present invention to provide an electronically controlled separate type fuel injection apparatus which is capable of controlling the timing of fuel injection independently of the amount of fuel injected.

It is another object of the present invention to provide an electronically controlled separate type fuel injection apparatus which is improved in its response characteristics.

It is a further object of the present invention to provide an electronically controlled separate type fuel injection apparatus in which the amount of fuel injected and the timing of fuel injection can be precisely and independently controlled.

According to the present invention, in an electronically controlled separate type fuel injection apparatus driven by a driving device provided in an internal combustion engine, the separate type fuel injection apparatus has a first adjusting member for adjusting the amount of fuel injection, a second adjusting member for adjusting the injection advance, a setting device for generating a speed signal indicative of a desired engine speed, a speed detector for producing an electric signal indicative of a rotational speed related to the rotational speed of the engine, a first circuit responsive to at least the electric signal from the speed detector and the speed signal from said setting device for producing an electric signal indicative of the position of the first adjusting member necessary for operating said engine at the speed indicated by said speed signal, a first controlling device responsive to the electric signal produced by the first circuit for adjusting the position of the first adjusting member, a second circuit responsive to at least the electric signal produced by the speed detector for producing an electric signal indicating the position of the second adjusting member necessary for obtaining the optimum injection advance for the operating conditions of the engine at that time, and a second controlling device responsive to the electric signal produced by the second circuit for adjusting the position of said second adjusting member.

With this arrangement, the position of the first adjusting member is controlled by the first controlling device so as to maintain the engine speed at the set value set by the setting means, and the position of the second adjusting member is controlled by the second controlling device so as to provide the optimum injection advance determined by the second circuit.Although the amount of fuel injected is varied with changes in the timing of fuel injection caused by the adjustment of the position of the second adjusting member, this change in the amount of fuel injected is fed back, in the form of a change in the engine speed, to the control system for adjusting the amount of fuel injected through the speed detector, so that the amount of fuel injected can be controlled so as to maintain the engine speed to the set value set by the setting device irrespective of the control of the injection advance.

Since the governing operation by the first controlling device as described above is carried out electronically, the operation range can easily be widened and since the governing operation can be carried out by a small-sized apparatus, the entire system can also be small-sized. In addition, the injection timing can be controlled with accuracy over a wide range. As described above, not.only can the control of the amount of fuel injected and the control of the timing of fuel injection be carried out independently of each other, but these controls can be effected in accordance with the operation parameters of the engine, so that fuel consumption can be remarkably reduced and the engine can be operated with optimum timing of the fuel injection for various kinds of fuels.

Further objects and advantages of the invention will be clear from the following detailed description to be read in conjunction with the accompanying drawings in which: Fig. 1 is a fragmentary perspective view of one embodiment of the present invention; Fig. 2 is a sectional view of one of the fuel injection pumps of Fig. 1; Fig. 3 is a sectional view of the fuel injection pump of Fig. 2 taken along the line A-A; Fig. 4 is a sectional view of the fuel injection pump of Fig. 2 taken along the line B-B; Fig. 5 is a diagram showing characteristic curves of the fuel injection pump of Fig. 2; Fig. 6 is a block diagram showing the control system of the fuel injection apparatus illustrated in Fig. 1; and Fig. 7 is a block diagram showing another form of the control system of the fuel injection apparatus illustrated in Fig. 1.

Referring to Fig. 1, there is illustrated an embodiment of the present invention wherein separate type fuel injection pumps are mounted on a marine diesel engine 1 having a plurality of cylinders. The number of injection pumps provided is equal to the number of cylinders of the diesel engine 1. In Fig. 1, only two fuel injection pumps 2 and 3 are illustrated. These fuel injection pumps are driven by cams secured to a drive shaft (not shown) in the diesel engine 1 so as to pressurize fuel supplied through a fuel feeding system not illustrated. The pressurized fuel from the fuel injection pumps is supplied to corresponding cylinders through injection pipes 4 and 5, respectively.For the purpose of adjusting the amount Q of fuel injected by the fuel injection pumps and the timing of the injection (injection advance 0), a first rack 6 for regulating the amount of fuel injection and a second rack 7 for regulating the timing of the beginning of the fuel injection, that is, the injection advance, are provided for the fuel injection pumps 2 and 3. These racks 6 and 7 are driven by first actuator 8 and second actuator 9, respectively. Numeral 10 designates a control unit for driving and controlling the first and second actuators 8 and 9.In response to a control signal (as will be described later) from the control unit 10, the first and second actuators 8 and 9 are operated to adjust the positions of the first rack 6 and the second rack 7 so that the respective fuel injection pumps operate with the desired amount of fuel injection and at the optimum injection advance for the conditions of operation of the diesel engine.

Fig. 2 iilustrates a cross section of the fuel injection pump 2 of Fig. 1. The fuel injection pump 2 has a casing 11 which is fixed to a housing 1 a of the diesel engine 1 by bolts. A plunger barrel 1 3 having at one end thereof a delivery valve 12 is disposed in the casing 11. A dual plunger 1 6 comprised of an inner plunger 14 for adjusting the amount of fuel injected and an outer plunger 15 for adjusting the injection advance is fitted in the plunger barrel 13 and a flange 16a formed at a lower end of the dual plunger 1 6 is biased downwardly by a compression spring 18 encased in a chamber 1 7 of the casing 11.

The outer plunger 1 5 is coaxially fitted on a small diameter portion 1 4a of the inner plunger 14 in such a way that the outer plunger 1 5 is prevented from moving relatively to the inner plunger 14 in the direction of its axis by the eniarged portions 1 4b and 1 4c which are formed at the upper and lower ends of the small diameter portion. 14a. As a result, the inner plunger 1 4 and the outer plunger 1 5 can be rotated independentls of each other in the circumferential direction but can only move conjointly with each other in the axial direction.Therefore, these plungers 14 and 1 5 can be made to reciprocate in the axial direction at the same time in accordance with the rotation of a cam 1 9 in the diesel engine 1.

On the outside of the dual plunger 1 6, there are coaxially provided a sleeve 20 for adjusting the rotational position of the inner plunger 1 4 and a sleeve 21 for adjusting the rotational position of the outer plunger 1 5.

A pair of legs 20a and 20b, which are spaced from each other in parallel, are formed at the lower end of the sleeve 20, and a key 1 4d integrally formed with the inner plunger 14 at its lower portion is fitted in the space formed between the legs 20a and 20b as shown in Fig. 3.

As will be seen from Figs. 2 and 3, the key 1 4d is inserted in the space so as to be free to move upward or downward therein. Therefore, the sleeve 20 can rotate conjointly with the inner plunger 14 but cannot restrict the movement of the inner plunger 1 4 in the axial direction. A pinion portion 20c is formed at the upper end portion of the sleeve 20 and is meshed with the first rack 6 inserted through the casing 11. A shim 22 receiving the force of the spring 1 8 is pressed onto a shoulder portion 20d of the pinion portion 20c, and the top surface 20e of the sleeve 20 is pressed onto a corresponding shoulder portion 11 a formed in the casing 11.As a result, the sleeve 20 is axially positioned as shown in Fig. 2, whereas its rotational position (degree of rotation about its axis) varies in accordance with the movement of the first rack 6 in its axial direction.

Therefore, the sleeve 20 can adjust the angular position of the inner plunger 14 in accordance with the axiai movement of the first rack 6 without causing the inner plunger 14 to move along its axis.

The other sleeve 21 has a pair of spaced parallel legs 21 a and 21 b and a key 15a integrally formed with the outer plunger 1 5 is fitted between the legs 21 a and 21 b (Fig. 4). As a result, the sleeve 21 can rotate conjointly with the outer plunger 15 but cannot restrict the movement of the outer plunger 1 5 in the axial direction.

The sleeve 21 is fitted inside the sleeve 20 by which it is supported and a pinion portion 21 c formed on the upper end portion of the sleeve 21 is meshed with the second rack 7. Thus, the rotational position of the outer plunger 1 5 (degree of rotation about its axis) can be adjusted in accordance with the movement of the second rack 7 in its axial direction without restricting the movement of the outer plunger 1 5 in its axial direction.

On the upper circumference surface of plunger 14 is a helix lead 24 for regulating the timing of the end of fuel injection and on the upper circumference surface of plunger 1 5 is a helix lead 25 for regulating the timing of the beginning of fuel injection. These helix leads 24 and 25 serve to change these timings by cooperating with ports 26 and 27 defined in the barrel 13.

The port 26 is closed by the side wall of the inner plunger 14 and the port 27 is aligned with the helix lead 25 when the dual plunger 1 6 is in the lowermost position (the position of Fig. 2), so that the fuel is not pressurized in a high-pressure chamber 23 upon rising of the dual plunger 1 6.

When the dual plunger 1 6 is further moved upwardly and the port 27 is closed by the side wall of the outer plunger 1 5, the fuel begins to be pressurized in the high-pressure chamber 23 and the pressurized fuel is fed to an associated injection pipe through the delivery valve 1 2. When the dual plunger 1 6 is further moved upwardly and the port 26 is aligned with the helix lead 24, the injection of the fuel is completed. The timings at which the ports 26 and 27 are closed or opened can be easily adjusted as desired by adjusting the rotational positions of the plungers 14 and 15.

In Fig. 5, the characteristic curve b shows how the injection amount changes with changing position Lb of the second rack 7 for regulating the injection advance and the characteristic curve a shows how the amount of fuel injected changes with changing position La of the first rack 6. From the characteristic curves shown in Fig. 5, it can be seen that the amount of the fuel injected is Q2-Q1 when La and Lb are L and L2, respectively.

Although the above description has been made referring only to one fuel injection pump 2, the other fuel injection pumps are constructed similarly, and the amount of fuel injected and the injection advance of these fuel injection pumps can be controlled concurrently by the positional adjustment of the racks 6 and 7.

Fig. 6 is a block diagram of the fuel injection control system of the fuel injection apparatus illustrated in Fig. 1. The control system has a speed setting device 51 for setting a desired engine speed Nr and a speed detector 52 for producing an analog signal S, having a level changing in accordance with the actual speed Na of the engine 1.Digital data D, indicating the set speed is output from the speed setting device 51 and the signal S, is fed to an A/D converter 53 which converts it into digital data D2 indicating the actual engine speed N a These data D, and D2 are input to a first computing circuit 54 which produces in digital form first position data D a showing the position X of the first rack 6 necessary to make the value of Na equal to the value of Nr The relationship among Nat Grand X may be determined in advance and the first computing circuit 54 may include a memory in which the data concerning the relationship is stored.In response to the application of the data D, and D2 representing Na and Nrt data indicative of the corresponding value of X is read out from the memory in the first computing circuit 54 and the data from the memory is output as first position data Da.

There is known an electronic circuit which includes a memory for storing resulting data determined on the basis of input data and which can output the stored data corresponding to the input data from the memory when the input data is applied to the electronic circuit. It is one of the prior art techniques to store the resulting data at the address of the memory designated by the input data corresponding to the resulting data and to obtain the resulting data by applying the input data to the memory as address data. (For example, U.S. Patent No. 3,689,753).

Therefore, as first computing circuit 54 there be used a ROM in which each value of X determined from the data D1 and D2 is stored in digital form at the address designated by the data D, and D2.

The control system further comprises a second computing circuit 55 for computing the optimum timing of fuel injection (injection advance) of the fuel injection pump. Data based on output signals from an air pressure detector 56, a temperature detector 57 for detecting the engine coolant temperature and an input device for entering data concerning the kind of fuel are applied to the second computing circuit 55 in addition to the data D2.The air pressure detector 56 produces an air pressure signal S2 having a level changing in accordance with the atmospheric pressure and the air pressure signal S2 is changed into digital form by an A/D converter 59 from which digital data D3 indicative of the detected atmospheric pressure value is produced In a similar way, a temperature signal S3 from the temperature detector 57 is converted into digital form by an A/D converter 60 to produce the digital data D4 indicative of the coolant temperature. The input device 58 for entering data concerning the kind of fuel, inputs data D5 indicative of the kind of fuel to the second computing circuit 55.

In response to these input data D2 to D5, the second computing circuit 55 produces a second position data do in the digital form, which is indicative of the second rack position Y necessary for obtaining the optimum injection advance at that time. The relationship amount these data D2 to D5 and position Y may also be determined in advance experimentally. Therefore, by the use of a memory in which the relationship between the position Y and a set of data D2 to D5 can be stored, the second computing circuit 55 may also be used a ROM in an arrangement similar to that of the first computing circuit 54.In this embodiment, the second computing circuit 55 has a memory to which data D2 to D5 are applied as address data and the corresponding data indicating the desired position Y determined by these data D2 to D5 is stored at the address designated by these data D2 to D5. As a result, when the data D2 to D5 are applied as address data to the second computing circuit 55, there is outputted second position data Db indicative of the optimum position Y of the second rack for the data D2 to D5.

The second position data Db from the second computing circuit 55 is converted into analog form by aD/A convertor 61 and the converted output signal is amplified by an amplifier 62. The output signal from the amplifier 62 is applied as a driving signal to the second actuator 9 and the second actuator 9 is driven in such a way that the second rack 7 is positioned at the desired position represented by the second position data Db.

As is obvious from the arrangement shown in Fig. 2, adjusting of the injection advance in accordance with the second position data Db will cause a change in the amount of fuel injected. For the purpose of compensating for the change in the amount of fuel injected caused by the adjustment of the injection advance, the first position data Da is input into a ROM 63 which serves to act as a data correcting circuit. The second position data Db is also input into the ROM 63 and a desired corrected position data Dc is output in accordance with both data Da and Db. The relationship among these data Dat D b and Dc can be determined in advance on the basis of the characteristic curves shown in Fig. 5.That is, since the values of Qt and Q2 are known from computing the target positions for the positions La and Lb of the racks 6 and 7 by the use of the circuits 54 and 55, the change in the amount of fuel injected effected by the value of the data Db can be estimated in advance. The data concerning the estimated amount of change is stored in the ROM 63 and the corrected daXa Dc is read out therefrom when the values of the data Da and Db are determined.In this embodiment, as well as the predescribed computing circuits, the data D a and D b are applied as read-out address data to the ROM 63 and the values of the data Dc which is to be determined by these data D a and Db gre stored at the addresses designated by the data Da and Db, respectively. Therefore, the application of the data Da and Db to the ROM 63 causes the ROM 63 to produce the corrected data Dc which is determined by the data Da and Db at that time.

The corrected data Dc is changed into the analog form by a D/A converter 64 and the converted analog signal is amplified by an amplifier 65. The output signal from the amplifier 65 is applied as a driving signal to the first actuator 8 and the first actuator 8 is driven to position the first rack 6 at the place represented by the corrected data Dc The correcting operation for the first position data Da by the use of the ROM 63 is for compensating in advance in an electrical form for the effect of the change in injection advance caused by the second position data Db. on the control system for adjusting the amount of fuel injected through a mechanical system, and it can remarkably improve the response characteristics of the control.

With this arrangement, the first rack 6 is controlled with respect to its position by the first actuator 8 so as to maintain the engine speed set by the speed setting device 31, and the second rack 7 is controlled with respect to its position by the second actuator 9 so as to provide the optimum injection advance based on the computation of the second computing circuit 55.

As described referring to Fig. 5, the amount of the fuel injected is varied with change in the injection advance caused by the adjustment of the position of the second rack 7. This variation of the amount of fuel injected is fed back, in the form of a change in the engine speed, to the control system for adjusting the amount of fuel injected through the speed detector 52, and the second position data Db is input as correcting data to the ROM 63.

Therefore, when the injection advance is regulated, the amount of fuel injected can be controlled independently of the control of the injection advance, and the amount of fuel injected can be controlled to a desired value set by the speed setting device 51 irrespective of the control of the injection advance. Since the governing operation by the first actuator 8 as described above is carried out electronically, the operation range can easily be widened and since the governing operation can be carried out by a smallsized apparatus, the entire system can also be small-sized. In addition, since the injection advance can be controlled with accuracy over a wide range, the fuel-consumption of the engine can be reduced remarkably and, moreover, even a fuel of poor quality can be combusted effectively.

Although the control is carried out using the engine speed, atmospheric pressure and coolant temperature as parameters indicating the operation conditions of the engine in the embodiment as described above, the parameters employed in the system of the present invention are not limited to these mentioned and other parameters may be used additionally or some of the above-mentioned parameters may be omitted.

Furthermore, although the above described embodiment is adapted to correct the data Da by the use of the ROM 63 in order to improve the response characteristics of the control system, it is not always necessary to electrically correct the data Da and the correcting operation may be omitted. Even if the ROM 63 is omitted and the first position data D a is directly input into the D/A converter 64, since the change in the amount of fuel injected caused by the adjustment of the injection advance is fed back in the form of a speed change to the input side of the speed control system through a solely mechanism system, the change is compensated for in the speed control system. Thus, the control of the amount of fuel injection can be carried out independently of the control of the injection advance.

Fig. 7 illustrates a block diagram of another embodiment of the fuel injection control system.

The control system illustrated in Fig. 7, differs from the control system of Fig. 6 mainly in that first and second position detectors 66, 67 for detecting the positions of the respective racks are provided and that a first position signal S4 indicating the position of the first rack 6 and a second position signal S5 indicating the position of the second rack 7 which are detected by the position detectors 66 and 67, respectively, are used as feed-back signals to form closed loop control circuits. In Fig. 7, parts similar to the corresponding parts in Fig. 6 are denoted by the same numerals and the description thereof is omitted.

On the basis of the data D, to D4,a computing circuit 68 produces in digital form a first target position data Dx representing the position of the first rack 6 at which the amount of fuel injected is that necessary for operating the engine at the target engine speed represented by the data D,.

The first target position data Dx is applied to another computing circuit 69 in addition to the data D2, D3, D4 and D5 to produce a second target position data Dy showing the position of the second rack 7 necessary for obtaining the optimum injection advance for the engine operating conditions at that time in digital form in accordance with these input data.

Like the computing circuits 54 and 56 shown in the embodiment of Fig. 6, these computing circuits 68 and 69 also use ROMs, and the input data are applied as read-out address data to the respective circuits. Thus, the data stored at the address denoted by these input data are output from the circuits 68 and 69 as the first and the second target position data Dx and Dv. The data to be stored in the computing circuits 68 and 69 may be determined, for example, experimentally, in a similar way to that in the predescribed embodiment The position data Dx and Dy are converted into analog form by the use of corresponding D/A converters 70 and 71 and a first target position signal Se from the D/A converter 70 is applied to one input terminal of a comparator 72 having another input terminal to which a first position signal 54 is applied. On the other hand, the second target position signal S7 is applied to one input terminal of a comparator 73 having another input terminal to which a second position signal Ss is applied.An output signal S8 having a level corresponding to the difference in level between the input signals S5 and S, is produced by the comparator 73, and the output signal S8 is applied as a driving signal to the second actuator 9 after being amplified by the amplifier 62. The output signal S5 of the second position detector 67 for detecting the position of the second rack 7.

positioned by the second actuator 9 is fed back to the control system, so that the position of the second rack 7 can be controlled with high accuracy in acordahce with the second target position data Dy.

The output signal Sg from the comparator 72 has a level corresponding to the difference in level between the signal S4 and S6 and is applied to a correcting circuit 74 whose function is the same as that of the ROM 63 of Fig. 6. The output signal S8 is also applied to the correcting circuit 74 and the output signal Sg is corrected in accordance with the level of the output signal S8. As a result, the operation of compensating for the change in the amount of fuel injected caused by the control of the.second rack 7 is electrically carried out in advance in the correcting circuit 74.In order to perform the above-mentioned correcting operation, there is used as the correcting circuit 74 a voltage controlled type variable gain amplifier whose gain varies in response to the level of the output signal S8 whereby the-level of the output signal Sg can be changed in accordance with the level change of the output signal S8.

According to the control system shown in Fig.

7, the injection advance can of course be controlled independently of the control of the amount of fuel injected, and moreover, more precise control of the positions of the racks can be realized since the system is arranged in such a way that information concerning the position of each racks is fed back to the control system. In addition, in this case, the parameters employed in the system of the present invention are not limited to those mentioned and other parameters may be used additionally or some of the above-mentioned parameters may be omitted.

Claims

1. An electronically controlled separate type fuel injection apparatus which is driven by a driving means provided in an internal combustion engine, comprising: a first adjusting member for adjusting the amount of fuel injected; a second adjusting member for adjusting the injection advance; a setting means for generating a speed signal indicative of a desired engine speed; means for producing an electric signal indicative of a rotational speed related to the rotational speed of said engine; a first circuit responsive to at least the electric signal from said producing means and the speed signal from said setting means for producing an electric signal indicative of the position of said first adjusting member necessary for operating said engine at the speed indicated by the speed signal:: a first controlling means responsive to the electric signal produced from said first circuit for adjusting the position of said first adjusting member, said first controlling means including a first actuator for driving said first adjusting member; a second circuit responsive to at least the electric signal produced from said producing means for producing an electric signal indicating the position of said second adjusting member necessary for obtaining the optimum injection advance for the operating condition of said engine at that time; and a second controlling means responsive to the electric signal produced from said second circuit for adjusting the position of said second adjusting member, said second controlling means including a second actuator for driving said second adjusting member.

2. An apparatus as claimed in Claim 1, wherein said first circuit is a memory device in which the data indicating the positions of aid first adjusting member are stored at addresses designated by the electric signals applied thereto and the dataindicating the desired position of said first adjusting member is read out therefrom in response to the application of the electric signals.

3. An apparatus as claimed in Claim 1, wherein said second circuit is a memory device in which the data indicating the positions of said second adjusting member are stored at addresses designated by the electric signals applied thereto and the data indicating the desired position of said second adjusting member is read out therefrom in response to the application of the electric signals.

4. An apparatus as claimed in Claim 1, which further comprises a correcting circuit in which electric signal output from said first circuit is corrected in advance to compensate for the change in the amount of fuel injection caused by the positional control of said second adjusting member based on the output electric signal from said second circuit.

5. An apparatus as claimed in Claim 4 wherein the correcting operation in said correcting circuit is carried out on the basis of the electric signal output from said second circuit.

6. An apparatus as claimed in Claim 1 wherein said first adjusting member is a first plunger having a helix lead for setting the timing of the end of the fuel injection, said first plunger being fitted into a barrel of a fuel injection pump, said second adjusting member is a second plunger having a helix lead for setting the timing of the beginning of the fuel injection, said second plunger being coaxially fitted with said first plunger so as to be axially reciprocated integrally with said first plunger by said driving means and to be rotatable about its axis independently of the rotation of said first plunger, whereby each timing is adjusted in accordance with the rotational position of the corresponding plunger.

7. An apparatus as claimed in Claim 6 wherein said first and said second actuators are adapted to drive racks which are meshed with pinions formed at portions of said first and second plungers, respectively, whereby the rotational positions of said plungers are controlled.

8. An apparatus as claimed in Claim 7 wherein said racks are commonly used for a plurality of separate type fuel injection pumps mounted on said engine.

9. An apparatus as claimed in Claim 1, further comprising: a first detector for generating a first position signal corresponding to the adjusted position of said first adjusting member; and a second detector for generating a second position signal corresponding to the adjusted position of said second adjusting member, said first and said second position signals being fed back to said first and said second controlling means, respectively, to form a closed loop control circuit.

10. An apparatus as claimed in Claim 1 - and substantially as hereinbefore described with reference to, and as shown in any one of the embodiments illustrated in the accompanying drawings.