Control device of common rail fuel injection system of an engine

• US 6,792,916 B2
• Filed: 08/30/2002
• Issued: 09/21/2004
• Est. Priority Date: 09/28/2001
• Status: Expired due to Fees

• Current Assignee: Isuzu Motors Limited
• Original Assignee: Isuzu Motors Limited
• Inventors: Oashi, Yoshiro
• Primary Examiner(s): MOULIS, THOMAS N
• Application Number:
  US10/232,336
• Publication Number:
  US 20030062030A1
• Time in Patent Office: 753 Days
• Field of Search: 123/510, 123/511, 123/446, 417/298
• US Class Current: 123/446
• CPC Class Codes: F02D 2041/2027 Control of the current by pulse width modulation or duty cycle control
• CPC Class Codes: F02D 2041/389 for injecting directly into the cylinder
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2250/31 Control of the fuel pressure
• CPC Class Codes: F02D 41/08 for idling F02D41/06, F02D41/16 take precedence
• CPC Class Codes: F02D 41/20 Output circuits, e.g. for controlling currents in command coils
• CPC Class Codes: F02D 41/3845 by controlling the flow into the common rail, e.g. the amount of fuel pumped
• CPC Class Codes: F02M 59/34 by throttling of passages to pumping elements or of overflow passages , e.g. throttling by means of a pressure-controlled sliding valve having liquid stop or abutment
• CPC Class Codes: F02M 63/0017 using electromagnetic operating means
• CPC Class Codes: F02M 63/004 Sliding valves, e.g. spool valves, i.e. whereby the closing member has a sliding movement along a seat for opening and closing

Abstract

To prevent the sticking of the valve body of an electromagnetic valve under idling conditions or under non-injection conditions in a control device of common rail fuel injection system of an engine wherein the fuel supplied from a feed pump (6) is pressurized to high pressure by a high-pressure pump (3) and the quantity of fuel supply to this high-pressure pump (3) is adjusted by an electromagnetic valve (7) whose degree of opening is controlled in accordance with a duty signal, the control frequency of the duty signal is altered to a lower frequency (λl) when an operating condition such that the degree of opening of the electromagnetic valve (7) is constant is detected. In this way, the energy or amplitude per current wave flowing in the electromagnetic solenoid (39) can be made larger, so making it possible to produce minute vibrations of the valve body (41). Sticking of the valve body (41) can thereby be prevented.

Claims

1. A control device of common rail fuel injection system of an engine comprising:

a high-pressure pump that pressurizes to a high pressure fuel supplied from a feed pump;

an electromagnetic valve which is located on a passage between this feed pump and high-pressure pump in order to adjust the quantity of fuel supply to the high-pressure pump; and

electromagnetic valve control means for controlling the degree of opening of this electromagnetic valve in accordance with a duty signal, said device further comprising;

detection means for detecting an operating condition of the control device such that the degree of opening of said electromagnetic valve is constant; and

control frequency alteration means for altering the control frequency of said duty signal to a lower frequency when such an operating condition is detected;

wherein said operating condition in which the degree of electromagnetic valve opening is constant in idling condition or non-injection condition of the engine.

2. The control device according to claim 1 for the engine for a vehicle, wherein said detection means identifies said operating condition in which the degree of opening of the electromagnetic valve is constant when the engine speed is in idling speed region, the transmission is in neutral position and the accelerator pedal is in a fully closed position.

3. The control device according to claim 1 for the engine for a vehicle wherein said detection means identifies said operating condition in which the degree of opening of the electromagnetic valve is constant when the engine speed is higher than the idling speed, the transmission is shifted in any gear position and the target fuel-injection quantity to the engine is zero.

4. The control according to claim 1 wherein, when the control frequency of said duty signal is altered to lower frequency, said control frequency alteration means corrects the duty ratio of said duty signal such that the average value of the current flowing in the electromagnetic solenoid of said electromagnetic valve is the same as if said control frequency had not been altered.

5. The control device according to claim 1, wherein said electromagnetic valve comprises an electromagnetic solenoid that is supplied with said duty signal, a spool-shaped valve body that is actuated in response to current flowing in this electromagnetic solenoid, and a spring that biases this valve body in the opening direction.

6. The control device according to claim 1 wherein the control frequency of said duty signal is normally no less than 170 Hz and no greater than 190 Hz, but is at least 120 Hz and less than 170 Hz when altered by said control frequency alteration means.

9. The control according to claim 1 wherein, when the control frequency of said duty signal is altered to lower frequency, said control frequency alteration means corrects the duty ratio of said duty signal such that the average value of the current flowing in the electromagnetic solenoid of said electromagnetic valve is the same as if said control frequency had not been altered.

10. The control according to claim 2 wherein, when the control frequency of said duty signal is altered to lower frequency, said control frequency alteration means corrects the duty ratio of said duty signal such that the average value of the current flowing in the electromagnetic solenoid of said electromagnetic valve is the same as if said control frequency had not been altered.

11. The control according to claim 3 wherein, when the control frequency of said duty signal is altered to lower frequency, said control frequency alteration means corrects the duty ratio of said duty signal such that the average value of the current flowing in the electromagnetic solenoid of said electromagnetic valve is the same as if said control frequency had not been altered.

12. The control device according to claim 1, wherein said electromagnetic valve comprises an electromagnetic solenoid that is supplied with said duty signal, a spool-shaped valve body that is actuated in response to current flowing in this electromagnetic solenoid, and a spring that biases this valve body in the opening direction.

13. The control device according to claim 2, wherein said electromagnetic valve comprises an electromagnetic solenoid that is supplied with said duty signal, a spool-shaped valve body that is actuated in response to current flowing in this electromagnetic solenoid, and a spring that biases this valve body in the opening direction.

14. The control device according to claim 3, wherein said electromagnetic valve comprises an electromagnetic solenoid that is supplied with said duty signal, a spool-shaped valve body that is actuated in response to current flowing in this electromagnetic solenoid, and a spring that biases this valve body in the opening direction.

15. The control device according to claim 4, wherein said electromagnetic valve comprises an electromagnetic solenoid that is supplied with said duty signal, a spool-shaped valve body that is actuated in response to current flowing in this electromagnetic solenoid, and a spring that biases this valve body in the opening direction.

16. The control device according to claim 1 wherein the control frequency of said duty signal is normally no less than 170 Hz and no greater than 190 Hz, but is at least 120 Hz and less than 170 Hz when altered by said control frequency alteration means.

17. The control device according to claim 2 wherein the control frequency of said duty signal is normally no Less than 170 Hz and no greater than 190 Hz, but is at least 120 Hz and less than 170 Hz when altered by said control frequency alteration means.

18. The control device according to claim 3 wherein the control frequency of said duty signal is normally no less than 170 Hz and no greater than 190 Hz, but is at least 120 Hz and less than 170 Hz when altered by said control frequency alteration means.

19. The control device according to claim 4 wherein the control frequency of said duty signal is normally no less than 170 Hz and no greater than 190 Hz, but is at least 120 Hz and less than 170 Hz when altered by said control frequency alteration means.

20. The control device according to claim 5 wherein the control frequency of said duty signal is normally no less than 170 Hz and no greater than 190 Hz, but is at least 120 Hz and less than 170 Hz when altered by said control frequency alteration means.

7. An electromagnetic valve control method for a control device of common rail fuel injection system of an engine wherein fuel supplied from a feed pump is pressurized to high pressure by a high-pressure pump and the quantity of fuel supply to this high pressure pump is adjusted by an electromagnetic valve whose degree of opening is controlled in accordance with a duty signal, comprising the steps of:

detecting an operating condition in which the degree of opening of said electromagnetic valve is constant; and

when such an operating condition is detected, altering the control frequency of said duty signal to a lower frequency.

8. An electromagnetic valve control device for a fluid circuit comprising an electromagnetic valve for adjusting the amount of working fluid and electromagnetic valve control means for controlling the degree of opening of this electromagnetic valve in accordance with a duty signal, said electromagnetic valve control device comprising:

detection means for detecting an operating condition in which the degree of opening of said electromagnetic valve is constant; and

control frequency alteration means for altering the control frequency of said duty signal to a lower frequency when such an operating condition is detected.