GB2031550A - Injection advance controller for diesel engines - Google Patents
Injection advance controller for diesel engines Download PDFInfo
- Publication number
- GB2031550A GB2031550A GB7928934A GB7928934A GB2031550A GB 2031550 A GB2031550 A GB 2031550A GB 7928934 A GB7928934 A GB 7928934A GB 7928934 A GB7928934 A GB 7928934A GB 2031550 A GB2031550 A GB 2031550A
- Authority
- GB
- United Kingdom
- Prior art keywords
- crankshaft
- camshaft
- injection
- differential
- cam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D1/00—Controlling fuel-injection pumps, e.g. of high pressure injection type
- F02D1/16—Adjustment of injection timing
- F02D1/18—Adjustment of injection timing with non-mechanical means for transmitting control impulse; with amplification of control impulse
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- High-Pressure Fuel Injection Pump Control (AREA)
- Fuel-Injection Apparatus (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
A fuel injection system including cam-actuated unit injectors (10) for a diesel engine is provided with means for adjusting the timing of injection according to engine operating conditions. The timing means includes a differential drive transmitting device (20) for coupling the camshaft (14) to the engine crankshaft (16). A servo (26) controls the position of the differential or control input of the differential device (20) to shift the phase of the camshaft (14) relative to the crankshaft (16) according to a control signal to obtain the desired advance or retardation of the initiation of injection. <IMAGE>
Description
SPECIFICATION
Injection advance controller for diesel engines
Technical field
This invention relates to fuel injection systems; more particularly it relates to the control of the timing of the commencement of injection of fuel into the engine cylinder.
Background art
In fuel injection systems for diesel engines, it is desirable to control both the fuel quantity and the timing of the fuel injection pulse according to engine operating parameters. In diesel injection systems, it is common practice to use cam-actuated unit injectors, i.e. a separate injector for each engine cylinder with a common camshaft for actuation of the injectors. In this arrangement, a control member, such as a fuel rack, is connected with each of the injectors for adjusting the quantity of injection according to engine operating requirements.
In one well known device, the unit injector has adjustable spill passages for controlling the commencement and termination of injection. One form of such device uses a rotatable sleeve which closes a first spill passage and opens a second spill passage for commencement and termination, respectively, of injection at crankshaft angles which are dependent upon the rotative position of the sleeve. This device has the effect of narrowing or widening the fuel injection pulse and hence it primarily governs the quantity of fuel injection. It advances or retards the commencement of injection as well as the termination of injection.
However, it does not afford independent control of metering of the fuel injection quantity and the timing of injection.
Also, diesel fuel injection systems are known in the prior art which provide for adjustment of injection timing independently of injection metering. Such an injection system is disclosed in the Dreisin patent 3,991,732. The system of this patent uses a multiple plunger pump; the plunger corresponding to a given cylinder is provided with a helical spill passage and a control sleeve is rotatably and reciprocably disposed over the plunger. The quantity of fuel to be injected is adjusted by a control rod which is adapted to rotate the control sleeve in response to certain engine operating conditions and establish the termination of injection by setting a spill passage in the sleeve for alignment with the helical spill passage.The timing of initiation of injection is adjusted by the control rod which is adapted to reciprocably position the control sleeve so that the helical spill passage is covered earlier or later in the plunger stroke.
Diesel injection systems are known in which injection timing is controlled by shifting the angular position of a camshaft which drives an injector pump. This is provided by means of a centrifugal control device having flyweights which act through cam members to rotate the pump camshaft relative to a driving shaft which may be connected with the crankshaft of the engine. Such as arrangement is described in the
Hofmann et al patent 3,834,184.
Summary ofthe invention
According to this invention, a fuel injection system having cam-actuated unit injectors provides control of injection timing in accordance with engine operating parameters. This is accomplished by a differential drive transmitting device for coupling the camshaft to the crankshaft, including means for adjusting the phase relation to the camshaft to the crankshaft.
Further, in accordance with this invention, timing of cam-actuated unit injectors is controlled in accordance with any one or combination of engine operating parameters by shifting the phase of the camshaft relative to the crankshaft. This is accomplished by a differential device, preferably a planetary gear set, for coupling the camshaft to the crankshaft and a servo with an actuator connected to the differential input of the device for shifting the phase of the camshaft according to an electrical signal applied to the input of the servo.
Further, according to this invention, an improved timing arrangement is provided for a diesel injection system of the type having cam-actuated unit injectors which pressurize the fuel to a value at which injection commences. This is accomplished by a phase-shifter for coupling the camshaft to the crankshaft for displacing the camshaft relative to the crankshaft in accordance with any desired control law. The phase-shifter preferably comprises a differential gear set, such as a planetary gear set. The differential gear set has one input connected with the crankshaft andean output connected with the camshaft with a predetermined drive ratio therebetween and the input of the gears set is connected with an actuator for shifting the phase of the output relative to the first input.
A more complete understanding of the invention may be obtained from the detailed description that follows, taken with the accompanying drawings.
Description of drawings
Figure lisa diagram of the fuel injection system of this invention;
Figure 2 shows the phase-shifter of this invention;
Figure 3 is a view taken on lines 3-3 of Figure 2;
Figure 4 is a view taken on lines 4-4 of Figure 2;
Figure 5 is a graphical representation to aid in describing operation of the subject invention, and
Figure 6 is a graphical representation to aid in describing operation of the invention.
Best mode for carrying out the invention
Referring now to the drawings, there is shown an illustrative embodiment of the invention in a fuel injection system for diesel engine. As shown in Figure 1, the system comprises a unit fuel injector 10 for each of the cylinders of the diesel engine. The injector 10 is mounted in the cylinder head 12 for direct injection of fuel into the respective cylinder. The injector 10 is of the cam driven type and is actuated by a camshaft 12.
The camshaft 14 is driven by an engine crankshaft 16 through a differential drive transmitting device or phase-shifter 20 which, in accordance with this invention, is adapted to adjust the phase angle between the camshaft and the crankshaft. The timing of fuel injection by the injector 10 is controlled, in general, by an injection advance controller 22 which receives an injection advance or phase control signal from an electronic control unit 24. The injection advance controller 22 includes a phase-shifter 20, a servo motor or actuator 26 and a servo amplifier 28.
The system also includes an injection metering servo or controller 30 which receives a fuel quantity control signal from the electronic control unit 24 and adjusts the duration of the fuel injection pulse of the injector 10.
The controller 30 comprises a servo motor or actuator 32 connected with an engine fuel control rack 34 which coacts with the injector 10. The actuator 32 is energized by a servo amplifier 36 in accordance with the metering control signal from the control unit 24.
The electronic control unit 24 is a computational unit which is supplied with a plurality of input signals on conductors 38 from a plurality of sensors. The inout signals represent selected engine operating parameters such as engine speed, throttle position, manifold air pressure and engine temperature. The electronic control unit operates to compute, in accordance with a given control law, the quantity of fuel and the timing of fuel injection for the given operating parameters. The timing of fuel injection may be expressed as an injection advance angle, i.e. the number of degrees of crankshaft angle displacement from top dead centre.The phase control signal mentioned above which is produced by the electronic control unit 24 represents the phase shaft angle of the camshaft relative to the crankshaft (suitablty measured from top dead centre) required for producing the computed injection advance. The phase control signal produced by the electronic control unit 24 is applied through a conductor 40 to the input of the amplifier 28. The output of the amplifier 28 is applied through a conductor 42 to the actuator 26. The actuator 26 is suitably provided with a feedback transducer (not shown) and the feedback signal is applied to the servo amplifier through a conductor 44. The actuator is thus energized to produce a displacement corresponding in magnitude and direction to the amplitude and phase of the phase control signal.
The fuel quantity signal computed by the electronic contril unit 24 represents the volume of fuel for a given injection. The metering control signal developed by the electronic control unit 24 represents the fuel volume; this quantity may be expressed in terms of the crankshaft angle at which injection is to be terminated, such being calculated relative to the crankshaft angle at which the injection is initiated. The metering control signal of the electronic control unit 24 is applied through a conductor 46 to the input of the amplifier 36 and the outoputthereof is applied through a conductor 48 to the actuator 32. The actuator 32 includes a feedback transducer (not shown) and a feedback signal is supplied to the amplifier through a conductor 50.The actuator 32 displaces the fuel control rack 34 through a distance having a direction and magnitude corresponding to the phase and amplitude of the metering control signal from the electronic control unit.
Although the actuator 26 for the coupling means 20 and the actuator 32 for the fuel control rack 34 have been described as electric motors, it will be understood that hydraulic actuators may also be used, depending upon the installation, with the hydraulic fluid being supplied by the fuel transfer pump in the fuel supply system.
The injector 10 is a cam-driven unit injector. It comprises an injector body 50 having a plunger 52 therein which is provided with a cam follower 54. The cam follower 54 engages a cam 56 on the camshaft 14. The injector 50 is supplied with fuel from a transfer pump (not shown) through a conduit 58. The injector has a fuel delivery or injection value in the tip 60 which opens in response to a predetermined value of injection pressure of the fuel in the pressure chamber 62 under the plunger 52. Accordingly, the initiation of the injection occurs at a predetermined point in the downward travel of the plunger 52. In order to control the duration of injection, and hence the volume or quantity of fuel, a control sleeve 64 in which the plunger reciprocates is provided with a spiral passage 66.The plunger 52 is provided at its lower end with a spill port 68 which will be aligned with the passage 66 when the plunger reaches a certain point in its downward stroke, depending upon the rotative position, of the control sleeve 64. The control sleeve 64 is rotatably positioned according to the metering control signal by the fuel control rack 34.
As described above, the injector 10 is controlled as to fuel quantity by the fuel metering controller 30 including the fuel control rack 34; it is controlled as to injection timing or injection advance, i.e. the crank angle at which injection commences, by the injection advance controller 22. The injection advance adjustment is accomplished by the coupling means 20 which will be decribed in detail below.
The differential drive transmitting device or phase shifter 20 is shown in Figures 2, 3 and 4. The phase shift comprises a differential gear set, preferably a planetary gear set 70, and is connected with the actuator 26 through a control arm or member 72. The planetary gear set is of conventional construction and is a speed ratio-changing power transmission device. It comprises a sun gear 74 which is connected with the engine crankshaft and consitutes the power input member. The gear set also includes a ring gear 76 which is connected with the camshaft 14 and constitutes the power output member. A differential member comprises a set of three pinions of planet gears 78 which are interposed between the sun gear and the ring gear. The gears 78 are rotatably mounted on a planet carrier 80 which is connected with the control member 72.
The angular position of the planet carrier 80 is controlled by the control member or arm 72. The control arm 72 is rotatably mounted on the power input shaft 16 and is connected with the planet carrier 80 by a drive pin 82. The control arm 72 is driven by the motor 26 through a lead screw 84 on the motor shaft and a travelling nut 86 which is pivotally mounted on the control arm 72.
In a diesel engine of the type which operates on a four-stroke cycle, the fuel is injected on alternate crankshaft rotations and, for this purpose, the camshaft is rotated at one-half the speed of the crankshaft. In the illustrative embodiment of the phase shifter 20, the desired speed ratio between the crankshaft and camshaft is obtained by a planetary gear set in which the internal ring gear 76 has twice as many teeth as the sun gear 74.The relationship of the rotation rates in a planetary gear set is given by: R2 = R3(1 + N1/N2) - R1(N1/NP) (1) where
R1 = Rotation rate of the sun gear
R2 = Rotation rate of the ring gear
R3 = Rotation rate of planet carrier N1 = Number of teeth on sun gear, and
N2 = Number of teeth on ring gear
From this relation, it is apparent that the camshaft 14 rotates at one-half the speed of the crankshaft 18 when the planet carrier 80 is held stationary and the sun gear 74 has one-half the number of teeth as the ring gear 76. The rotation rate of the camshaft, as given by equation (1) has a negative sign which indicates that the camshaft rotation is opposite in direction of the crankshaft rotation.It can be seen by inspection of equation (1) that rotation of the planet carrier 80 will add or subtract to the rotation rate of the camshaft 14 depending upon the direction of rotation of the planet carrier. If, for example, clockwise rotation of the sun gear, as viewed in Figure 3, is taken as the positive direction of rotation, the positive term in equation (1) indicates that the rotation rate of the ring gear will be less negative when the rotation rate of the plane carrier is positive; in other words, with clockwise rotation of the crankshaft the camshaft rotation will be counterclockwise and will be slowed down by the clockwise rotation of the planet carrier. Total rotation of the ring gear 76 is given by integration over the time period in question of equation (1).Thus:
and,
R2 At = R3(1 + N1/N2) At - R1 (N1/N2) At (3) where At = t2 - t1 Equation (3) expresses the relative angular displacement of the camshaft 14 which is accumulated over a given increment of time relative to the crankshaft 18 by a given rotation rate of the planet carrier 80; in other words, it expresses the phase shift produced in the camshaft relative to the crankshaft for a given increment of rotation of the planet carrier 80, and hence the control arm 72. Where the rotation rate is expressed in degrees per second and the increment of time At is expressed in seconds, the phase shift angle is expressed in degrees.Thus an angular displacement of the planet carrier 80 by a certain number of degrees changes the accumulated phase shift of the camshaft 14 relative to the crankshaft 18 by a factor equal to one plus the ratio of the number of teeth in the sun gear to the number of teeth in the ring gear. Thus, for example, a ten degree rotation of the plant carrier 80 results in fifteen degrees rotation of the camshaft 14 relative to the crankshaft 16.
In operation of the engine, this relationship is illustrated in the graphs of Figures 5 and 6. These graphs represent a condition in which the engine is running at constant speed over a given interval of time during which the phase shifter 20 is operated first in one direction and then in the other direction. In Figure 5, the crankshaft angular velocity is shown as a function of crankshaft angle and, over the time interval in question it is a constant value represented by line A. The camshaft angular velocity is represented by line B and the planet carrier angular velocity is represented by line C over the same interval. Prior to the occurrence of crankshaft angle a1 the planet carrier velocity is zero, and accordingly, the camshaft velocity is one-half the crankshaft velocity.As shown in Figure 6, the camshaft angle increases lineraly with crankshaft angle during the time prior to crankshaft angle al. Accordingly, the phase relation between the camshaft and the crankshaft remains constant throughout the interval prior to crankshaft angle 1,. Beginning at angle a1, as shown in Figure 5, the planet carrier 80 is moved with a given angular velocity in one direction during the crankshaft angular interval from a1 to a2, and then the motion is stopped at a2. This causes the camshaft angular velocity to change in the same sense as indicated by line B in Figure 5. As a result, during the crankshaft interval from a1 to a2 the change in the camshaft angle is less than it would be if the planet carrier has remained stationary.As shown in Figure 6, the camshaft angle is changed from b1 to b2 whereas it would have changed from b1 to b3 if the planet carrier has remained stationary. Thus, the camshaft is shifted in phase relative to the crankshaft by the difference between b3 and b2. At the crankshaft angle a2 when the motion of the planet carrier is stopped, the camshaft angle becomes a linear function of crankshaft angle until the planet carrier is moved again. As shown in Figure 5 at line C, the planet carrier is moved in the opposite direction during the interval a3 to a4. This causes the camshaft velocity to change in the opposite sense as indicated by line B in Figure 5. As a result, the camshaft angle increase more during the interval than it would have if the planet carrier has remained stationary.This produces a positive phase shift of the camshaft relative to the crankshaft as illustrated in Figure 6.
From the foregoing, it will now be appreciated that the injection timing is controlled by the phase shifter 20 in accordance with the phase control signal from the electronic control unit 24. The phase shift of the camshaft 14 relative to the crankshaft 18 produced by the phase shifter 20 has the effect of advancing or retarding the initiation of injection since the injection starts when the injector plunger reaches a certain point in its downward stroke, as discussed above. The response time of the injection advance controller 22 only need be fact enough to cope with engine acceleration of deceleration.
Although the description of this invention has been given with reference to a particular embodiment, it is not to be construed in a limiting sense. Many variations and modifications will now occur to those skilled in the art. For a definition of the invention, reference is made to the appended claims.
Claims (10)
1. For use in a fuel injection system for an engine having a crankshaft, a camshaft adapted to be driven by the crankshaft and having a cam thereon, a fuel injector having a cam-actuated plunger operatively connected with said cam for pressurizing fuel in the injector to a value at which injection commences, the improvement comprising a differential drive transmitting device having input and output members adapted to be connected respectively with the crankshaft and camshaft, said device having a differential member, and means coupled with said differential member for shifting the phase relation between the input and output members.
2. The invention as defined in claim 1 wherein said means includes a reversible actuator coupled with said differential member.
3. The invention as defined in claim 1 wherein said means includes a servo having an actuator coupled with said differential member and a servo amplifier for energizing the actuator and adapted to receive an electrical control signal corresponding to a desired timing of initiation of injection.
4. The invention as defined in claim 1 wherein said differential drive transmitting device as a planetary gear set.
5. The invention as defined in claim 4 wherein said planetary gear set has a sun gear adapted to be connected with said crankshaft, a ring gear adapted to be connected with said camshaft, a planet gear, and a planet gear carrier coupled with said means.
6. Afuel injection system for an engine having multiple cylinders and a crankshaft, said system comprising a unit injector for each of said cylinders and having a cam-actuated plunger for pressurizing fuel in the injector to a value at which injection commences, a camshaft having plural cams mounted thereon, there being one cam for each cylinder of the engine, each cam being disposed in operative relation with a cam actuated plunger of a respective injector, a differential drive transmitting device having an input member adapted to be connected with the crankshaft, an output member connected with the camshaft, and a differential member for shifting the phase relation between the input and output members, a control member connected with said differential member, and means for actuating the control member in reversible direction while the output member is rotatably driven by said input member whereby the phase of the camshaft may be shifted relative to the crankshaft for advancing or retarding the crankshaft angle at which injection is initiated in each of said injectors.
7. The invention as defined in claim 6 wherein said differential drive transmitting device is a planetary gear set.
8. The invention as defined in claim 7 wherein said planetary gear set comprises a sun gear, a ring gear, and at least one planet gear, a planet gear carrier connected with the planet gear, said sun gear being adapted for connection with the crankshaft, said ring gear being connected with said camshaft, and said
planet gear carrier being connected with said control member.
9. The invention as defined in claim 6 wherein said means for actuating is a servo including an actuator connected with said control member and a servo amplifier for energizing the actuator and adapted to receive an electrical phase control signal corresponding to the desired timing of initiation of injection.
10. A fuel injection system substantially as described and as shown in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US94647378A | 1978-09-28 | 1978-09-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2031550A true GB2031550A (en) | 1980-04-23 |
Family
ID=25484515
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7928934A Withdrawn GB2031550A (en) | 1978-09-28 | 1979-08-20 | Injection advance controller for diesel engines |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5549535A (en) |
| DE (1) | DE2939446A1 (en) |
| GB (1) | GB2031550A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0059587A2 (en) * | 1981-03-03 | 1982-09-08 | Caterpillar Inc. | Fuel pump control system |
| US4378775A (en) * | 1980-07-01 | 1983-04-05 | Robert Bosch Gmbh | Method and apparatus for fuel injection in internal combustion engines in particular diesel engines |
| US4449501A (en) * | 1980-12-31 | 1984-05-22 | Lucas Industries Limited | Device for adjusting engine timing |
-
1979
- 1979-08-20 GB GB7928934A patent/GB2031550A/en not_active Withdrawn
- 1979-09-28 DE DE19792939446 patent/DE2939446A1/en not_active Withdrawn
- 1979-09-28 JP JP12423779A patent/JPS5549535A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4378775A (en) * | 1980-07-01 | 1983-04-05 | Robert Bosch Gmbh | Method and apparatus for fuel injection in internal combustion engines in particular diesel engines |
| US4449501A (en) * | 1980-12-31 | 1984-05-22 | Lucas Industries Limited | Device for adjusting engine timing |
| EP0059587A2 (en) * | 1981-03-03 | 1982-09-08 | Caterpillar Inc. | Fuel pump control system |
| EP0059587A3 (en) * | 1981-03-03 | 1985-05-08 | Caterpillar Tractor Co. | Timing and position measuring system |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2939446A1 (en) | 1980-04-17 |
| JPS5549535A (en) | 1980-04-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |