JP2001248490A - Sychronization of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly synchronize an internal combustion engine when the engine is started. SOLUTION: A four-stroke internal combustion engine 1 has a plurality of cylinders 11-14 having pistons I-IV connected with a crankshaft 36, means 32-34 for imparting a series of pulses in each engine cycle and an engine control system 10. The engine control system 10 has a memory 44 and means 10, 29, 32 for judging the engine cycles after the engine 1 is cranked and a means 9 for counting the series of pulses till the engine l is stopped to judge the engine cycles when the engine 1 is stopped afterwards so as to store data showing the engine cycles into the memory 44. From a certain point of view, the means 10, 29, 32 for judging the engine cycles after the engine 1 is cranked are means for judging the engine cycles during the operation of the engine 1. From an another point of view, the means 10, 29, 32 for judging the engine cycles after the engine 1 is cranked includes the memory 44 storing data showing the engine cycles before the engine 1 is cranked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the synchronization of a four-stroke internal combustion engine during engine start.

[0002]

2. Description of the Related Art When a fuel injection type internal combustion engine is started, in order to optimize performance and emission from the engine,
It is desirable to supply fuel to each cylinder at the correct time, and then, for gasoline engines, sparks. To determine the engine cycle of the engine, two general methods are used, either a single sensor that detects the rotational position of the crankshaft or a pair of sensors, one on the camshaft and the other on the crankshaft. There is a way. A single sensor on the camshaft
It is relatively expensive and must also be timed to meet the required accuracy. The other approach is
Although an inexpensive sensor that does not require time adjustment is used, preparing two sensors increases the manufacturing cost.

[0003] Ideally, it is desirable to use only one sensor that does not require time adjustment, ie, only the crankshaft sensor. The crankshaft sensor gives an accurate signal according to the rotational angular position of the crankshaft, but cannot clearly determine the engine cycle in a four-stroke engine. For example, in a four-cylinder engine, the crank signal cannot distinguish between the first cylinder and the fourth cylinder or between the second cylinder and the third cylinder.

US Pat. Nos. 5,425,340 and 5,613,473 disclose a method which aims at judging the engine cycle when there is only a crankshaft sensor. In both of these documents, engine control systems intentionally misfire one or more cylinders. This causes the engine output to drop immediately after the misfire,
As a result, a slight decrease in the engine speed that can be detected from the crankshaft signal occurs. Although this approach is effective in determining the engine cycle, the misfire is noticeable to the driver and the driver will determine such a misfire upon engine start-up as a malfunction of the engine.

Furthermore, such misfires have a negative effect on the emission performance of an automobile engine. Such misfires during cranking of the engine do not affect this emission performance if the rated emission performance is measured during steady-state operation of the engine, but include the period from the start of the engine. Rated emission performance for stricter regulations will be affected.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a more preferred method of synchronizing an internal combustion engine when starting the engine.

[0007]

SUMMARY OF THE INVENTION In accordance with the present invention, a four-stroke internal combustion engine is provided which comprises a plurality of cylinders having pistons connected to a crankshaft, means for providing a series of pulses in each engine cycle, and An engine control system including a memory and means for determining an engine cycle after the engine has been cranked, the engine control system including a memory for storing data representative of the engine cycle in the memory; Means for counting a series of pulses until the engine stops, in order to determine the engine cycle when the engine stops.

The means for determining the engine cycle after the engine has been cranked may include means for determining the engine cycle during operation of the engine, for example, at some point after cranking the engine. is there.

[0009] The means for determining the engine cycle after the engine has been cranked may also include memory for storing the engine cycle before the engine is cranked.

[0010] The means for measuring engine rotation may include a sensor for measuring crankshaft rotation that generates a series of pulses as output each time the crankshaft rotates.

[0011] The memory is preferably a non-volatile memory, such as an EEPROM or a flash memory, and may optionally be integrated with the engine control system.

The sensor can be configured to directly measure the rotation of the crankshaft. For example, the crankshaft has a toothed wheel and the sensor is configured to detect the passage of a tooth as the crankshaft rotates.

The sensor may be any type of sensor, and is preferably a non-contact type sensor, such as a Hall effect sensor or a variable reluctance sensor. Hall effect sensors have the advantage of producing an output even when the crankshaft speed reaches zero. Variable reluctance sensors are inexpensive but provide an output signal with an amplitude that varies directly with crankshaft rotation speed. In this case, the means for counting the pulses includes, for the last pulse, prediction means for inferring the engine cycle from the frequency and amplitude of the decreasing pulse.

The prediction means may be an empirically derived algorithm or a look-up table constructed according to the performance measurements of the sensor device.

Thus, it is possible to compensate for pulse amplitude variability such that the final stop position of the crankshaft can be determined, for example, to an accuracy defined by the number of output pulses per revolution of the crankshaft.

In a preferred embodiment of the present invention, the means for counting the pulses when the engine comes to a stop is provided in addition to the engine cycle so that data representing the rotational angle of the stopped engine is stored in a memory. Measure the rotation angle of the engine.

When the engine is started, the engine control system may synchronize the fuel supply to the cylinders with a series of pulses, eg, a pulse output from a crankshaft sensor, and a series of pulses stored in memory. Data can be used. In the case of a direct or indirect injection engine, synchronization may include timing of a fuel injection event. Similarly, for a spark ignition engine, synchronization may include a cylinder ignition event. Thus, upon starting the engine, synchronization can be made quickly, and when the engine is started, the engine performance including emission performance is improved.

Further, according to the present invention, a plurality of cylinders having a piston interlocked with a crankshaft, means for generating a series of pulses in each engine cycle, and determination of an engine cycle after a memory and an engine are cranked. A method for synchronizing a four-stroke internal combustion engine having an engine control system including means for counting and a series of pulses, the method comprising the steps of: a) providing a series of pulses in each of the engine cycles; b) providing a series of pulses to the engine control system; and c) determining an engine cycle, the method comprising: d) determining the engine cycle of the engine to be shut down at a later time. Counting a series of pulses until the engine stops, and e) storing data representing the engine cycle of the stopped engine in memory. It characterized by having a step, to be stored in.

Step c) may include the step of determining the engine cycle during engine operation, for example at some point after cranking the engine.

Step c) may include storing in a memory data representing the engine cycle of the engine before the engine is cranked.

Optionally, step c) comprises determining the rotational angle of the stopped engine, in which case step e)
May include storing data representing the rotation angle of the stopped engine.

Later, when the engine is to be started, the data previously stored in memory can be recalled. So, when the engine is cranked, the engine control system will
Tracking or counting of a series of pulses can be performed. This allows the fueling of the cylinders to be synchronized according to the recalled data and the output from the means for providing a series of pulses.

If the engine is a spark ignition engine, the cylinder ignition events can be synchronized according to the recalled data and the means for producing a series of pulses.

The invention will now be described in more detail, by way of example, with reference to the drawings, in which:

[0025]

FIG. 1 shows a four-cylinder four-cycle internal combustion engine having a multipoint fuel injection system in which fuel is supplied to each of cylinders 11, 12, 13, and 14 by an electromagnetic injection valve 2 which may be a direct or indirect injection valve. 1 schematically shows an institution 1. In this example, the engine is a gasoline engine and also has a spark plug 4. However, the invention is also applicable to diesel engines and to engines with fewer or more cylinders.

The injection timing of the electromagnetic injection valve 2 and the ignition timing of the spark plug 4 are controlled by an electronic engine control system 10, which determines the amount of fuel, the injection timing and the ignition timing according to the engine operating conditions. The engine control system 10 receives an input signal, performs an operation, and generates an output control signal particularly to the fuel injector 2 and the spark plug 4. As before, the electronic engine control system 10 includes a microprocessor (μP) 9, a random access memory (RAM) 15, a read-only memory (ROM) 16, an analog-to-digital converter (A / D) 18, and an ignition plug·
It has various input / output interfaces, including a driver 20 and an injection valve driver 22.

The input signal is a driver request signal (DD) 2
4. An engine temperature signal (T) 26, an exhaust oxygen signal (EGO) 28 from an exhaust oxygen sensor 29, and a VRS signal 30 from a variable reluctance sensor (VRS) 32, all of which are sent to the microprocessor 9. Before, A / D converter 18
Digitized by

For an engine operated at 6250 rpm
Referring also to FIG. 2, which shows the VRS signal 30, a variable reluctance sensor 32 detects the passage of circumferentially spaced teeth 33 at the periphery of the flywheel 34 on the engine crankshaft 36. . Flywheel 34
Has a general configuration referred to herein as 36-1 teeth, where 35 identical teeth 33 are equally spaced by 35 gaps, and a pair of teeth are They are arranged at three times the interval. A large gap corresponds to one missing tooth. Thus, the VRS signal 30 has a series of pulses for each revolution of the crankshaft, along with one missing pulse, indicated generally at 38 in FIG. Digitization of the original VRS signal 30 by the A / D converter 18
One missing pulse 42 corresponding to missing pulse 38 at 30
Digital VR with a series of essentially square waves
An S signal 40 is generated.

The presence of the missing tooth indicates that the top dead center (TD
C) can be specified. For example, the last digital pulse 44 before the missing pulse 42 can be 90 ° before TDC. For a four-cylinder four-stroke engine with four pistons I, II, III, IV, the engine TDC
The position is also the TDC position of pistons I and IV in one engine cycle and the TDC position of pistons II and III in the next cycle. FIG. 1 shows pistons I and IV located at top dead center.

In the illustrated in-line four-cylinder four-stroke engine, showing an ignition sequence according to the order of 1-3-4-2, pistons I and IV (or II and III) advance simultaneously to the TDC position, but from the engine cycle. Are in the suction (or compression) stroke and the other is in the expansion (or exhaust) stroke. Each piston goes through two cycles, each forming a 360 ° angle between the four phases or strokes of the cylinder during the intake / compression stroke and the expansion / exhaust stroke. Flywheel 34 rotates through an angle of 720 ° during two cycles, and variable reluctance sensor 32 generates two pulses indicating the TDC position of engine 1. Therefore, although the VRS signal gives a good measured value of the angle after one rotation of the flywheel 34, it is impossible to determine from a VRS signal 30 alone which of two engine cycles a certain cylinder is in. is there.

However, once the engine cycle is known, tracking the engine cycle is possible in principle by counting a series of pulses in the VRS signal 30. As used herein, the term "count" includes any means of tracking or identifying a pulse so that the engine control system can distinguish between the two cycles. For example, for a four-cylinder engine,
The count value will cycle repeatedly from 1 to 4, such as 1, 2, 3, 4, 1, 2, 3, etc. As described in more detail below, the engine control system 10 includes means for determining an engine cycle while the engine is running, and a series of VRS pulses when the engine is stopped to determine the engine cycle for a stopped engine. And both means for counting. Once the engine is stopped, data representing the engine cycle and possibly the engine rotation angle is stored in a memory, here an electronically erasable and programmable read only memory (EEPROM). When the engine is to be restarted, this data is recalled by the microprocessor 9 and this data is generated using a series of VRS pulses 30 when the engine starts to rotate.
Enables the microprocessor to properly time the fuel and ignition events according to the order of 1-3-4-2 to ignite the engine.

FIG. 3 shows a flowchart of the operation of the engine control system 10 and the engine control software running in the microprocessor 9. When the engine is started for the first time, the engine control system 10 has no record of the engine stop cycle or rotation angle.
This lack of data is indicated by the zero value stored in EEPROM 44. Such a zero value, for whatever reason, will cause the engine control system 10 to
If it is not possible to determine the stop cycle of
May be stored in PROM 44.

When the driver turns an ignition key (not shown), the microprocessor receives a driver request signal 24 which instructs the microprocessor 9 to start a sequence of operations 50 for starting the engine 1. Microprocessor 9 reads the data from EEPROM 44 and verifies that it is non-zero (step 52). If the data is zero (54), each cylinder has 4
The microprocessor controls all cylinders 11-1 to receive two injection commands and two ignition events during the two process cycles.
For 4, fuel injection and ignition events are scheduled for both engine cycles, and cranking and ignition of the engine 1 are started (step 56).

The engine control system 10 initiates a procedure whereby the engine cycle is determined so that fuel and ignition can be supplied to each cylinder 11-14 at the correct engine rotation angle once per two cycles (step 58). ). U.S. Patent 5,425,
Following the teachings of 340 or 5,613,473, the engine cycle can be determined quickly, in which cylinders 11-1
Fuel to one of four is cut. Referring to FIGS. 4A and 4B, this will result in a drop in the VRS frequency and crankshaft angular velocity expected for the cylinder during the expansion stroke.

Once the engine rotation angle has been determined, the microprocessor 9 provides a VRS to track the engine cycle.
Continue tracking or counting pulses. Then, at the correct engine rotation angle, the microprocessor 9
One fuel and ignition event every two engine cycles
4 (step 60).

At certain intervals, the microprocessor verifies whether the engine has been stopped (step 62). If the engine is running (64), the engine is tested to make sure that the engine cycle is still correct (step 66). Such a test may be performed by thinning out one cylinder of fuel and measuring the change in the VRS signal. Generally, this will cause perceived engine roughness. However, such verification need not be rapid, as the engine cycle is still likely to be known correctly. So, the engine control system runs the engine rich,
More robust but slower tests may be performed, such as monitoring the signal 28 from an exhaust oxygen (EGO) sensor 29, which is typically located at 68. EGO sensors have relatively fast response times, 50-100 ms. If the cycle for a particular cylinder is known correctly, 10
For an engine operating at 00 rpm, the response at EGO sensor 29 will appear approximately 500 ms after injection for that cylinder. This time delay is due to fuel injection,
It is the sum of the delays for the intake stroke, the compression stroke, the combustion delay, and the time taken during the delay in transporting the exhaust in the exhaust passage 68. If the engine cycle is known incorrectly, the time delay will be one cycle, that is, the engine speed is 1000 rpm
Will be shortened by 60 ms. The correlation between the injection timing and the response delay of the EGO signal is monitored to confirm that the cycle is correct. If the cycle is not correct, the engine control system 10 immediately switches to the correct cycle, and again verifies the EGO signal to verify that the time is correct.

This method of synchronizing the engine could optionally be used only when the engine is started or whenever the value stored in the EEPROM is zero.

As soon as the engine is turned off (70),
As shown in FIGS. 5A and 5B, the microprocessor 9 starts the final counting of the VRS pulse 30. As the engine speed decreases, the frequency and amplitude of the VRS pulse 30 decrease respectively. The A / D converter 18 has a resolution of 32 bits so that it can distinguish between a rising and a falling sine VRS pulse between a maximum of ± 20 volts and a minimum of ± 0.1 volts. The microprocessor 9 has a predicted VRS amplitude of 7 to help prevent false triggering when the amplitude of the VRS signal decreases.
2 Reduce the high frequency cut that decreases as
Includes a programmable digital signal processor (not shown) applied to the filter.

Digital VRS by microprocessor 9
The digital processing of the signal 40, as shown in the upper row of the sequence of integers labeled C in FIG.
Allowing the VRS pulse to be identified and counted (73). In the example shown, the series of VRS pulses 30 in FIG. 5A includes a missing pulse 38 so that
C at this location has no count. The VRS pulse feature of a stopped engine ensures that the time between zero crossings 74 is extended, so that software running in the microprocessor can easily determine that pulse 38 is missing. . Thus, the microprocessor modifies the count C, like the count C 'in FIG. 5B. The last count of C 'is used by the microprocessor 9 to calculate the correct engine cycle and possibly the engine rotation angle.

When the engine is stopped, there will typically be a reversing motion of the flywheel 34 as the piston moves to level the gas pressure in the cylinders 11-14. Such a reversal motion will result in an additional pulse 76, which when identified by the microprocessor will cause the modified count C 'to be decremented. For example, if the engine flywheel has 36-1 teeth, as long as the final count C 'is accurate to ± 17 teeth, the engine will be cranked and the first missing tooth 38 will be detected in the VRS signal 30. Immediately, the correct engine cycle can be determined accurately.

Instead of detecting individual pulses when the amplitude and frequency fall to zero, the microprocessor 9 calculates the envelope 72 of the waveform 30 and calculates the number of inference counts according to the decay rate of the envelope 72. Or could be read from a lookup table.

Returning to FIG. 3, and explaining the remainder, the next time the engine is to be started (50), the microprocessor 80 reads the non-zero value in the EEPROM 44 (80),
Load to microprocessor 9 (step 8
2). When the engine is cranked (step 84)
Then, as soon as the VRS pulse 30 appears to track the engine cycle, it begins to track or count it. At the correct time during each cylinder's four strokes, the stored data is used in conjunction with the VRS pulse 30 to ignite the engine with continuously supplied fuel injection and ignition events for each cylinder 11-14. The engine then performs periodic verification of the correct engine cycle and EEPROM 44
The final count of the VRS pulse is stored and activated.

Although the initial calibration of the engine cycle in step 58 of FIG. 3 may cause noticeable roughness of the engine, once the engine cycle is known, this is used whenever the engine is restarted. The information is stored. Thus, the initial calibration 58 does not normally need to be repeated.

Thus, the apparatus and method according to the present invention enable an engine cycle during normal operation of the engine to be determined without the need to cause a deliberate misfire of the cylinder, except when the engine is first started. And

As compared with a system in which the engine cycle needs to be determined every time the engine is started, the present invention enables an improvement in the emission performance immediately after the engine is started.

Known engine control systems typically include a microprocessor to handle complex calculations and control operations, and modifications or additions to be made to perform synchronization in the manner described. Can be obtained essentially by modifications and additions to existing microprocessor programs.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. . Rather, the terms used in the specification are words of description rather than limitation,
It is understood that various changes may be made without departing from the spirit and scope of the invention.

[0048]

According to the present invention described above, synchronization can be quickly performed at the start of the engine, so that when the engine is started, the engine performance including the emission performance is improved. Can be done.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a four-cylinder four-stroke internal combustion engine according to the present invention having an engine control system that receives an engine speed signal from a sensor that detects the passage of a flywheel tooth on a crankshaft.

FIG. 2 is a graph of signals from sensors before and after digitization by an engine control system.

FIG. 3 is a flowchart showing control of the engine by the engine control system.

FIG. 4 (A) shows a sensor signal (4A) during misfiring of a cylinder,
(B) is a graph showing a crankshaft angular velocity.

5A shows the sensor signal when the engine is stopped, and FIG. 5B shows the original count of the intersection of the digitized sensor signal with the threshold of the digitized signal by the engine control system and the corrected signal. It is a graph which shows a count.

[Explanation of symbols]

 1 4-stroke internal combustion engine 11-14 cylinder 32-34 sensor 36 crankshaft 30 pulse 44 memory I-IV piston

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ray Charles Marshall, England 23 Hartfordshire, England, St Albans Long Farlow 52 F-term (reference) 3G084 AA03 BA15 BA17 CA01 CA07 DA04 DA09 DA10 EA11 EB16 EC02 FA35 FA36 FA38

Claims (15)

[Claims] 1. A plurality of cylinders having pistons (I-IV) connected to a crankshaft (36), means (32,33,34) for providing a series of pulses (30) in each engine cycle, and memory. (44) and means (58,82) for judging the engine cycle after cranking the engine (1) (10,29,3)
2), the engine control system (10) comprising: a memory (44) for storing data representing an engine cycle; Judge the engine cycle of 1) (7
3) A four-stroke internal combustion engine comprising means (9) for counting (66) a series of pulses (30) until the engine (1) stops. The means (10, 29, 32) for determining an engine cycle after the engine is cranked includes a means (58) for determining (58) an engine cycle during operation of the engine (1). , 29, 32). 3. The means (10, 29, 32) for determining (82) an engine cycle after the engine has been cranked.
The four-stroke internal combustion engine of claim 1, wherein the engine (1) includes a memory (44) for storing data representative of an engine cycle of the engine before the engine (1) is cranked. 4. The engine control system (10) includes: the series of pulses (30) when the engine (1) is started, to synchronize fuel supply to the cylinder;
The method according to claim 3, wherein data stored in the memory (44) and representing an engine cycle of the engine (1) before the engine (1) is cranked is used.
4-stroke internal combustion engine. 5. The engine according to claim 1, wherein the engine is a spark ignition engine.
And the engine control system (10) also stores the memory (44) in the memory (44) and synchronizes the engine (1) before the engine (1) is cranked in order to synchronize cylinder ignition events. Data representing the engine cycle
The four-stroke internal combustion engine according to claim 4, which is used when the engine is started. 6. The means (32,33,34) for providing a series of pulses (30) to each engine cycle of the engine (1),
2. The sensor of claim 1, further comprising: a sensor for measuring rotation of the crankshaft, the sensor generating a series of pulses as an output for each rotation of the crankshaft. 3. A four-stroke internal combustion engine according to any one of claims 1 to 5. 7. The crankshaft (36) has toothed wheels (33, 34), and the sensor (32) detects passage of the teeth (33) when the crankshaft (36) rotates. The four-stroke internal combustion engine (1) according to claim 6, wherein the internal combustion engine (1) is configured to perform the following. 8. The amplitude of the series of pulses (30) changes in proportion to the rotation speed of the crankshaft (36), and the means (9) for counting the pulses (30) reduces the pulses. A four-stroke internal combustion engine according to any of the preceding claims, comprising prediction means (9) for inferring the engine cycle for the last pulse from the frequency and the amplitude. 9. The means (9) for counting a pulse (30) when the engine (1) stops is provided with an engine so that data representing the stopped engine rotation angle can be stored in the memory (44). The method of claim 1, further comprising determining a rotation angle of the stopped engine in addition to a cycle.
A four-stroke internal combustion engine according to any one of claims 8 to 13. 10. A plurality of cylinders (11-14) having pistons (I-IV) interlocked with a crankshaft (36), means (32,33,30) for providing a series of pulses (30) in each engine cycle.
34) and means (10, 29, 32) for determining the engine cycle after the memory (44) and the engine (1) are cranked (58, 82) and counting the series of pulses (30). Means (9) and an engine control system (10),
A method for synchronizing a four-stroke internal combustion engine (1) comprising: a) providing a series of pulses (30) in each engine cycle of the engine (1); b) a series of pulses to the engine control system (10). (3
0), and c) determining the engine cycle (58,82), the method comprising: d) determining (73) the engine cycle of the engine (1) which was later shut down. Steps (66, 7) for counting a series of pulses (30) until the engine (1) stops.
3) and e) storing (78) data representing the engine cycle of the stopped engine (1) in the memory (44), wherein the method comprises the steps of: (78). 11. The method for synchronizing a four-stroke internal combustion engine according to claim 10, wherein said step c) comprises a step (58) of determining an operating engine cycle of said engine (1). 12. The step (c) includes a step (78) of storing data representing an engine cycle of the engine (1) in the memory (44) before the engine (1) is cranked. Method for synchronizing a four-stroke internal combustion engine. 13. f) retrieving from said memory (44) said data representative of the engine cycle of said engine before said engine (1) is cranked; g) cranking said engine. (84) and h) a series of pulses (30) when the engine (1) is started and the engine (1) are synchronized in order to synchronize the fuel supply to the cylinders (11-14). 13. The method of synchronizing a four-stroke internal combustion engine (1) according to claim 12, comprising using the recalled data (44) representing the engine cycle of the engine (1) before cranking. 14. The engine is a spark ignition engine, wherein step h) comprises a series of pulses (30) when the engine (1) is started, also to synchronize cylinder ignition events; 14. Synchronizing a four-stroke internal combustion engine according to claim 13, including using the recalled data (44) representing the engine cycle of the engine (1) before the engine (1) is cranked. Method. 15. The step c) includes a step (73) of determining an engine rotation angle of the stopped engine (1), and the step e) includes an engine rotation angle of the stopped engine (1). A method for synchronizing a four-stroke internal combustion engine according to any of claims 10 to 14, comprising the step of storing data representing the following in the memory (44).