JP4331581B2 - Engine positive pressure gas fuel supply method and apparatus - Google Patents

Description

  The present invention relates to a positive pressure gas fuel supply method and apparatus for adjusting LPG or CNG to a predetermined positive pressure gas and supplying the engine to an engine using an electronically controlled injection valve. The present invention relates to a positive pressure gas fuel supply method and apparatus used in a gas injection system.

  The use of LPG as a fuel for spark ignition engines is widely known. Instead of the conventionally known method in which vaporized gas adjusted to a pressure of about atmospheric pressure using a regulator (vaporizer) and a mixer is sucked into an intake pipe and supplied to an engine, it is replaced with a conventional method. As described in Japanese Patent No. 17709 and the like, there is considered a system in which a positive pressure gas adjusted to a predetermined pressure is injected into an intake pipe and supplied to an engine. On the other hand, since CNG maintains a gas state more stably than LPG, it is put into practical use that it is adjusted to a predetermined positive pressure gas, injected into the intake passage, and supplied to the engine.

  When the injection system for supplying the positive pressure gas is mounted on the engine, an electronic control device that sets an injection amount that gives an optimal fuel supply amount according to the engine operating state is used for a new engine. The system can be designed and constructed from the beginning to control the injection valve.

However, for an existing engine equipped with a gasoline injection system, an injection amount that gives an optimal fuel supply amount according to the operating state of the engine is set in an electronic control device constituting the gasoline injection system. Therefore, an electronic control unit with a very simple function of calculating the positive pressure gas injection amount that gives the same mixture based on the gasoline injection amount is added, and it is suitable for positive pressure gas injection By using an injection valve having a valve diameter and a dynamic range, a positive pressure gas injection system can be constructed by using an existing gasoline injection system as it is, and can be modified to an engine using positive pressure gas fuel .

  In such a positive pressure gas injection system, the gasoline injection valve drive signal output from the gasoline electronic control device in the gasoline injection system is input to the positive pressure gas electronic control device, where a predetermined positive pressure gas is supplied. A positive pressure gas injection valve drive signal is output in terms of the injection amount. The positive pressure gas injection valve drive signal, which is the result of the positive pressure gas electronic control device calculating the positive pressure gas injection amount in response to the gasoline injection valve drive signal output by the gasoline electronic control device, is It is output in synchronization with the input of the gasoline injection valve drive signal.

  On the other hand, in a normal gasoline injection system, the throttle valve opening amount and its change are not used for the purpose of preventing the air-fuel mixture from becoming temporarily thin due to fuel wall flow or control response delay during acceleration, and deteriorating engine operability. The amount is detected, and based on this, interrupt injection is performed during a normal injection cycle as necessary, and the fuel is instantly enriched. Therefore, a positive pressure gas injection system obtained by remodeling such a gasoline injection system also takes in the interrupt injection signal during acceleration and injects positive pressure gas.

However, an electronic control device for positive pressure gas having only the above-mentioned function cannot accurately discriminate between a normal injection signal and an interrupt injection signal, and therefore accurately determines the amount of positive pressure gas to be interrupted. Since it cannot be calculated, it is not easy to obtain a required gas mixture for the positive pressure gas injection amount during acceleration. In particular, when starting with a light accelerator pedal depression in the drive range, since the change in throttle valve opening amount and intake air amount is small, interrupt injection is not performed, the engine misfires and engine operability is extremely deteriorated Problems are likely to occur.
JP-A-6-17709.

  The present invention is intended to solve the above-described problems. For a positive pressure gas injection system using a gasoline injection system, an interrupt injection signal can be accurately determined from a gasoline injection valve drive signal during acceleration. At the same time, it is an object to improve the engine operability during acceleration by determining the interruption injection amount of the positive pressure gas corresponding to this so that a required air-fuel mixture can be obtained.

  Therefore, the present invention calculates the positive pressure gas injection amount by inputting the gasoline injection valve drive signal output by the gasoline electronic control device provided in the engine to the existing gasoline injection system according to the engine operating state. A positive pressure gas injection system that includes an electronic control device for positive pressure gas and a positive pressure gas injection valve is added, and the positive pressure gas electronic control device gives a calculated positive pressure gas injection amount The above-mentioned problem of the positive pressure gas fuel supply method of the engine that outputs the valve drive signal to the positive pressure gas injection valve in synchronization with the input of the next gasoline injection valve drive signal is solved as follows.

  That is, the electronic controller for positive pressure gas monitors at least one of the injection cycle, injection time, and cylinder injection order from the gasoline injection valve drive signal, and discriminates the normal injection signal and the interrupt injection signal from the monitoring result. To determine the interrupt injection signal in the gasoline injection valve drive signal using a preset logic, determine the interrupt injection amount of the positive pressure gas using a preset interrupt injection amount calculation method, The interrupt injection of the positive pressure gas is performed almost in synchronization with the determined gasoline injection valve drive signal.

  This makes it possible to immediately determine the interrupt injection signal in the gasoline injection valve drive signal and perform an interrupt injection of an accurate amount of positive pressure gas without being delayed by this signal. It is possible to improve the acceleration operability of the engine by setting the injection amount to an appropriate amount.

  In addition, the items to be monitored by the electronic controller for the positive pressure gas from the gasoline injection valve drive signal include at least the injection cycle and the injection time, and the logic for determining the interrupt injection signal is 2 in one cycle of the same cylinder. If it is recognized that the injection signal is the second injection signal and the injection signal smaller than the previous injection signal is determined as an interrupt injection signal, the processing load for the determination is relatively small and almost synchronized with the injection signal. Thus, an interrupt injection signal of positive pressure gas can be output.

  Alternatively, at least the cylinder injection order is included in the items monitored from the gasoline injection valve drive signal, and the injection signal input in the order different from the normal injection order is determined as the interrupt injection signal. If this is done, there is no need to wait until the injection signal to be discriminated is completed, so that the time required for discrimination can be further reduced and synchronization can be achieved without delay.

  Further, in addition to the monitoring items described above, this electronic controller for positive pressure gas shall monitor the intake pipe pressure, and the interrupt injection amount calculation method will calculate the interrupt injection amount according to the amount of change in the intake pipe pressure. If so, the positive pressure gas injection amount can be calculated in detail according to the acceleration situation, so that the acceleration operability of the engine can be further improved, and in addition to this, the electronic controller for the positive pressure gas If the engine temperature is monitored and the interrupt injection amount is calculated according to the amount of change in the intake pipe pressure and the engine temperature, the positive pressure gas injection amount will be made more finely and appropriate depending on the acceleration status and the engine temperature. The acceleration operability of the engine can be made even better.

  Furthermore, a positive pressure gas electronic control device having a storage means storing a program for executing the above-described engine positive pressure gas fuel supply method, a cylinder filled with gas fuel, and an extension from the cylinder. The pressure line and the delivery line in which the positive pressure gas injection valve is arranged are added to the gasoline fuel supply device already installed in the engine to constitute a positive pressure gas injection system, and the positive pressure gas fuel supply of the engine If the positive pressure gas fuel supply device for an engine is characterized in that the method is executed, the above-described methods can be carried out at a relatively low cost.

  According to the present invention, the interrupt injection signal can be accurately determined from the gasoline injection valve drive signal during acceleration. In addition, it is possible to improve the engine operability at the time of acceleration by appropriately setting the interrupt injection amount of the positive pressure gas corresponding thereto.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an arrangement view showing an embodiment in which LPG is used for positive pressure gas fuel, and is a delivery pipe having a filter 3 and an electromagnetically driven shut-off valve 4 extending from a liquid phase portion of a cylinder 1 filled with LPG. The path 2 is connected to the pressure regulator 5.

  The pressure regulator 5 has a cooling water chamber 6 through which engine cooling water is circulated, a preheating chamber 7 to which the delivery pipe 2 is connected, and a pressure regulation chamber 8 to which a positive pressure gas pipe 14 is connected. The cooling water chamber 6 and the preheating chamber 7 are adjacent to each other and heat exchange is performed between the engine cooling water and the LPG. The pressure regulating chamber 8 is variable in volume by a diaphragm 10 on which an adjustment spring 9 is applied, and a conduction path 11 that connects the preheating chamber 7 and the pressure regulating chamber 8 rotates according to the displacement of the diaphragm 10. It is opened and closed by an inlet valve 13 attached to the lever 12.

  The liquid phase LPG that has entered the preheating chamber 7 from the cylinder 1 through the delivery line 2 is heated by the engine cooling water in the cooling water chamber 6 to become a vaporized gas, and this vaporized gas has the pressure in the pressure regulating chamber 8 set pressure. The inlet valve 13 flows into the pressure regulating chamber 8 by opening the conduction path 11 when the pressure is lower than the value, and the flow into the pressure regulating chamber 8 is stopped by closing the conduction path 11 when the inlet valve 13 is higher than the set pressure. . As a result, the vaporized gas produced in the preheating chamber 7 is held in the pressure regulating chamber 8 as a positive pressure gas adjusted to a predetermined pressure.

  The present invention is applied when an existing gasoline engine equipped with a gasoline injection system including an electronic control device 15 for gasoline and a gasoline injection valve 17 is modified to a gas engine. The gasoline electronic control unit 15 outputs a gasoline injection valve drive signal calculated based on the engine operating state 18 such as throttle valve opening, intake air amount, intake negative pressure, engine rotation speed, cooling water temperature, exhaust oxygen concentration and the like. The gasoline injection valve 17 is opened and closed with a duty cycle corresponding to the drive signal, and the gasoline of the required flow rate is injected and supplied to the engine. This is well known.

  In the present embodiment, a positive pressure gas injection system including an LPG electronic control device 21 and a positive pressure gas injection valve 23 is added with the gasoline injection system remaining. In this case, the gasoline injection valve 17 can be removed and replaced with the positive pressure gas injection valve 23. At this time, the drive signal line 16 from the gasoline electronic control unit 15 to the gasoline injection valve 17 is directly used as the LPG electronic type. It is connected to the control device 21 as an input signal line.

  However, in the case where the gasoline injection valve 17 is left without being removed and the positive pressure gas injection valve 23 is installed at an appropriate location near the gasoline injection valve 17 as in the illustrated embodiment, the electronic control device for LPG from the drive signal line 16 is used. A branch line reaching 21 is provided as an input signal line 24. The gasoline injection valve 17 opens and closes in response to a gasoline injection valve drive signal. However, by taking measures such as emptying or removing the gasoline fuel system, the gasoline injection valve 17 simply repeats opening and closing without injecting gasoline, There is no problem in implementing the present invention.

  Here, it is conceivable to use the gasoline injection valve 17 for the injection of the positive pressure gas. However, the positive pressure gas is larger in each stage than the gasoline in the volume flow rate corresponding to the engine required fuel flow rate. Then, a dedicated positive pressure gas injection valve 23 having a valve diameter and a dynamic range capable of proper injection of positive pressure gas is used. The LPG electronic control device 21 calculates an appropriate injection amount of the positive pressure gas based on the gasoline injection valve drive signal output by the gasoline electronic control device 15 in accordance with the engine operating state 18, and this calculation is performed. A positive pressure gas injection valve drive signal that gives the positive pressure gas injection amount is output to the positive pressure gas injection valve 23 through the drive signal line 22. In addition, an intake pipe pressure 25 and an engine temperature 26 are input to the LPG electronic control device 23.

  Next, referring to the layout diagram in FIG. 1 and the injection timing diagram for each cylinder in FIG. 2, the gasoline-specific electronic control device 15 outputs the gasoline injection valve drive signal T1, for each cylinder output according to the engine operating state 18. T2, T3, and T4 are input to the LPG electronic control device 21 through the input signal line 24. The LPG electronic control device 21 changes the gasoline to the flow rate required by the engine based on the input signal. Positive pressure gas injection valve drive signals A0, A1, A2, A3 for injecting positive pressure gas are calculated.

  The calculated positive pressure gas injection valve drive signal A1... Is output in synchronization with the next gasoline injection valve drive signal T2. That is, A1 calculated based on T1 is output in synchronization with the input of the next T2, and thereafter, similarly, the drive signal calculated based on the previous input is output in synchronization with the next input.

  When the driver accelerates by operating the accelerator pedal, an interrupt injection signal Tx is output in a normal gasoline injection valve drive signal T1... As shown in the injection timing chart of FIG. In this case, it is not easy to determine the interrupt injection signal Tx output after T1 in the normal LPG electronic control device 21 as the interrupt injection signal. Further, even if it can be discriminated, if the interrupt injection signal Ax of the positive pressure gas corresponding to this is after A1, the injection gas cannot be immediately concentrated in response to the driver's acceleration operation, so smooth acceleration Cannot be performed.

  Therefore, in the present embodiment, the order of the gasoline injection valve drive signals T1... For each cylinder is detected in the ROM built in the LPG electronic control device 21 and input in a different order from the normal injection order. Is stored as an interrupt injection signal Tx, and a program for outputting an interrupt injection signal Ax of LPG gas in synchronization with the recognized interrupt injection signal Tx is stored. The interrupt injection signal Tx can be determined and dealt with. Further, in this ROM, when outputting the interrupt injection signal Ax of the LPG gas, the acceleration state of the engine is judged based on the amount of change in the intake pipe pressure (intake manifold pressure) 25 being monitored, and the engine temperature 26 A program is also stored that determines the temperature state of the engine, determines the interrupt injection amount of the LPG in accordance with the acceleration state and the temperature state, and outputs an injection signal in accordance with this. The acceleration state is data necessary for determining the rate of increase of the interrupt injection amount, and the temperature state is useful data for correcting the flow rate of LPG having a large pressure change due to temperature.

  Next, the operation of the LPG electronic control device 21 in the present embodiment will be described using the flowchart of FIG. When detecting the gasoline injection signal Tn (A1), the LPG electronic control device 21 determines the correctness of the order based on whether or not this matches the predetermined order of the cylinder-specific injection signals (A2). If this is correct, it is determined that there is no interrupt injection signal Tx (A3), and a normal LPG gas injection amount is calculated based on the monitored engine temperature 26 (A4). Then, a normal LPG gas injection signal An is output in synchronization with the injection signal Tn + 1 according to the calculation result.

  On the other hand, when it is determined in A2 that the injection order for each cylinder is not correct, it is determined that there is an interrupt injection signal Tx (B1), and the interrupt injection amount of LPG gas is determined based on the intake pipe pressure 25 and the engine temperature 26. After calculating (B2), an LPG interrupt injection signal Ax is output in synchronization with Tx (B3).

  As described above, in the present embodiment, when it is recognized that the injection signal is in an order different from the order of the gasoline injection signal set in advance for each cylinder, it is determined as an interrupt injection signal, and the process waits for the end of the signal. Since it can be determined without necessity and can be immediately responded, an LPG interrupt injection signal can be output almost in synchronization with the determined signal. Therefore, it is possible to obtain a good acceleration by supplying a necessary amount of LPG immediately in response to the acceleration of the engine.

  On the other hand, as shown in the flowchart of FIG. 5, unlike the program for executing the method for determining the interrupt injection signal in the present embodiment, the gasoline injection signal Tn is detected (A6). When an injection signal is input (A7), it is determined whether or not the second injection signal Tn is an injection signal with an injection time shorter than the first injection signal Tn-1 (B4). The present invention can also be implemented using a program that determines that there is an interrupt signal Tx (B5). In this case, the process proceeds from step B5 to the same steps B6 and B7 as B3 and B4 in FIG. 4, and when it is determined NO in A7 and B4, the same steps A8, A9 and A5 as in A3, A4 and A5 in FIG. Proceed to A10. In addition, although it can implement similarly even if CNG is used as positive pressure gas, the preheating chamber 7 becomes unnecessary in the pressure regulator 5 in this case.

The layout which shows embodiment of this invention. The injection timing diagram which shows the gasoline injection valve drive signal input into the electronic control apparatus for LPG of FIG. 1, and the LPG injection valve drive signal output corresponding to this. FIG. 3 is an injection timing diagram when an interrupt injection signal is included in the gasoline injection valve drive signal in FIG. 2. The flowchart which shows operation | movement of the electronic control apparatus for LPG of FIG. The flowchart which shows operation | movement of the electronic control apparatus for LPG using the different determination method from the interruption injection signal determination method of FIG.

Explanation of symbols

1 cylinder, 2 supply line, 5 pressure regulator, 15 electronic control unit for gasoline, 21 LPG electronic control unit, 23 LPG injection valve, 25 intake pipe pressure, 26 engine temperature

Claims (6)

For positive pressure gas that calculates the positive pressure gas injection amount by inputting the gasoline injection valve drive signal output by the gasoline electronic control device provided in the engine to the existing gasoline injection system according to the engine operating state A positive pressure gas injection system comprising an electronic control device and a positive pressure gas injection valve is added, and the positive pressure gas electronic control device provides a positive pressure gas injection valve drive signal that gives the calculated positive pressure gas injection amount. In the positive pressure gas fuel supply method of the engine that outputs to the positive pressure gas injection valve in synchronization with the input of the next gasoline injection valve drive signal,
The electronic controller for the positive pressure gas monitors at least one of the injection cycle, the injection time, and the injection sequence of the cylinder from the gasoline injection valve drive signal, and discriminates the normal injection signal and the interrupt injection signal from the monitoring result. Determining an interrupt injection signal in the gasoline injection valve drive signal using a preset logic for determining the interrupt injection amount of positive pressure gas using a preset interrupt injection amount calculation method, and An interrupt injection signal for positive pressure gas is output almost in synchronization with the gasoline injection valve drive signal determined to be an injection signal.
A positive pressure gas fuel supply method for an engine.   Items to be monitored from the gasoline injection valve drive signal by the electronic controller for positive pressure gas include at least the injection cycle and injection time, and the logic for determining the interrupt injection signal is 2 in one cycle of the same cylinder. 2. The positive pressure gas fuel supply method for an engine according to claim 1, wherein when the second injection signal is recognized, an injection signal smaller than the previous injection signal is determined as the interrupt injection signal.   Items to be monitored from the gasoline injection valve drive signal by the electronic controller for the positive pressure gas include at least the injection order of the cylinder, and the logic for determining the interrupt injection signal is input in a different order from the normal injection order. The positive pressure gas fuel supply method for an engine according to claim 1, wherein the injected injection signal is determined as the interrupt injection signal.   The electronic controller for the positive pressure gas monitors the intake pipe pressure in addition to the monitor item, and the interrupt injection amount calculation method calculates the interrupt injection amount according to the change amount of the intake pipe pressure. The method for supplying positive pressure gas fuel for an engine according to claim 1, 2 or 3.   The positive pressure gas electronic control unit monitors the intake pipe pressure and the engine temperature in addition to the monitor items, and the interrupt injection amount calculation method determines the interrupt injection amount according to the change amount of the intake pipe pressure and the engine temperature. The positive pressure gas fuel supply method for an engine according to claim 1, 2, or 3. 6. An electronic controller for positive pressure gas comprising storage means for storing a program for executing the positive pressure gas fuel supply method for an engine according to claim 1, 2, 3, 4, or 5, and gas fuel A filled cylinder and a delivery line extending from the cylinder and provided with a pressure regulator and a positive pressure gas injection valve are added to the existing gasoline injection system to constitute a positive pressure gas injection system. A positive pressure gas fuel supply apparatus for an engine, which executes the positive pressure gas fuel supply method.

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