Search

EP-4735751-A1 - PRESSURE REGULATOR

EP4735751A1EP 4735751 A1EP4735751 A1EP 4735751A1EP-4735751-A1

Abstract

A pressure regulator (1) for a common rail of a high pressure hydrogen injection system, the pressure regulator (1) comprising: an inlet (5) for delivering fuel into the pressure regulator (1), an outlet (10) for supplying fuel out of the pressure regulator (1) and into the common rail, a fuel path for fuel flow between the inlet (5) and the outlet (10), a valve (20) movable between a closed position, wherein the valve (20) is arranged to block the fuel path, and a plurality of open positions, wherein the valve (20) is arranged to at most partially block the fuel path, each open position corresponding to a different position of the valve (20) with respect to the fuel path, a dual-spring system (25) arranged to urge the valve (20) towards the closed position, the dual-spring system (25) comprising a first spring (35) with a first compression characteristic and a second spring (40) with a second compression characteristic different to the first compression characteristic, and a solenoid actuator (30) configured to draw the valve (20) away from the closed position against the action of the dual-spring system (25) to one of the open positions when the solenoid actuator (30) is supplied with current, wherein the pressure regulator (1) is configured such that: the valve (20) is maintained in the closed position when the solenoid actuator (30) is not supplied with current, the first spring (35) is compressed by a first distance thereby providing a first phase of movement of the valve (20), when the solenoid actuator (30) is supplied with current less than or equal to a current threshold, and the second spring (40) is compressed by a second distance thereby providing a second phase of movement of the valve (20) following the first phase of movement, when the solenoid actuator (30) is supplied with current exceeding the current threshold.

Inventors

  • Guerrato, Diego

Assignees

  • Phinia Delphi Luxembourg Sarl

Dates

Publication Date
20260506
Application Date
20240628

Claims (13)

  1. 1. A pressure regulator (1) for a common rail of a high pressure hydrogen injection system, the pressure regulator (1) comprising: an inlet (5) for delivering fuel into the pressure regulator (1), an outlet (10) for supplying fuel out of the pressure regulator (1) and into the common rail, a fuel path for fuel flow between the inlet (5) and the outlet (10), a valve (20) movable between a closed position, wherein the valve (20) is arranged to block the fuel path, and a plurality of open positions, wherein the valve (20) is arranged to at most partially block the fuel path, each open position corresponding to a different position of the valve (20) with respect to the fuel path, a dual-spring system (25) arranged to urge the valve (20) towards the closed position, the dual-spring system (25) comprising a first spring (35) with a first compression characteristic and a second spring (40) with a second compression characteristic different to the first compression characteristic, and a solenoid actuator (30) configured to draw the valve (20) away from the closed position against the action of the dual-spring system (25) to one of the open positions when the solenoid actuator (30) is supplied with current, wherein the pressure regulator (1) is configured such that: the valve (20) is maintained in the closed position when the solenoid actuator (30) is not supplied with current, the first spring (35) is compressed by a first distance thereby providing a first phase of movement of the valve (20), when the solenoid actuator (30) is supplied with current less than or equal to a current threshold, and the second spring (40) is compressed by a second distance thereby providing a second phase of movement of the valve (20) following the first phase of movement, when the solenoid actuator (30) is supplied with current exceeding the current threshold.
  2. 2. The pressure regulator (1) of Claim 1 , wherein the first spring (35) has a first stiffness and the second spring (40) has a second stiffness, and wherein the first stiffness is larger than the second stiffness.
  3. 3. The pressure regulator (1) of Claim 1 or Claim 2, wherein the first spring (35) and the second spring (40) are arranged in series, and wherein the first spring (35) is preloaded with a first force and the second spring (40) is preloaded with a second force, and wherein the first force is less than the second force.
  4. 4. The pressure regulator (1) of any preceding claim, wherein the solenoid actuator (30) comprises a movable armature (105) coupled to the valve (20), and wherein the movable armature (105) is configured to compress the first and second springs (35, 40) in dependence on the current supplied to the solenoid actuator (30).
  5. 5. The pressure regulator (1) of Claim 4, wherein the armature (105) is configured to compress the first spring (35) through direct engagement with the first spring (35).
  6. 6. The pressure regulator (1) of Claim 4 or Claim 5, wherein the dual-spring system (25) comprises an intermediate element (120) and the armature (105) is configured to compress the second spring (40) through engagement with the intermediate element (120).
  7. 7. The pressure regulator (1) of Claim 6, wherein the pressure regulator (1) is configured such that a gap (165) is defined between the armature (105) and the intermediate element (120) when the solenoid actuator (30) is not supplied with current, and the armature (105) is operable to compress the second spring (40) via the intermediate element (120) only once the armature (105) has moved through the gap (165).
  8. 8. The pressure regulator (1) of Claim 6 or Claim 7, wherein the pressure regulator (1) is configured such that the armature (105) remains engaged with the intermediate element (120) during the second phase of movement, thereby preventing the armature (105) from compressing the first spring (35) during the second phase of movement.
  9. 9. The pressure regulator (1) of any of Claims 6 to 8, wherein the intermediate element (120) includes a first annular portion (145) defining a first recess, and wherein the first recess encloses at least a part of the first spring (35).
  10. 10. The pressure regulator (1) of any of Claims 6 to 9, wherein the intermediate element includes a second annular portion (150) defining a second recess, and wherein the second recess encloses at least a part of the second spring (40).
  11. 11. The pressure regulator (1) of any of Claims 6 to 10, wherein the armature (105) is annular and defines an armature recess (123) , and wherein the armature recess (123) encloses at least a part of the intermediate element (120).
  12. 12. The pressure regulator (1) of any preceding claim, wherein the pressure regulator (1) comprises a first adjustment means (140) for adjusting a first preload on the first spring (35).
  13. 13. The pressure regulator (1) of any preceding claim, wherein the pressure regulator (1) comprises a second adjustment means (135) for adjusting a second preload on the second spring (40).

Description

PRESSURE REGULATOR FIELD OF THE INVENTION This invention relates to a pressure regulator for a common rail of a fuel injection system. In particular, the invention relates to a pressure regulator for regulating the pressure of a high pressure gaseous fuel such as hydrogen in the common rail of a high pressure gaseous fuel injection system. BACKGROUND In fuel injection systems (FISs), it is known for a fuel pump to supply fuel to a high- pressure accumulator (or common rail), from where it is delivered by means of a dedicated fuel injector into each cylinder of an engine for combustion. Maintaining an acceptable delivery accuracy from the fuel injector is a technical challenge, particularly as the quantity of fuel to be delivered can vary across a broad range. The problem can be exacerbated by variations in common rail pressure and so it is important to maintain consistent pressures within the common rail at all times, regardless of the timing of the injector injection cycles. For this purpose, one or more pressure regulators are provided between the fuel pump and the common rail to regulate the pressure of the fuel within the common rail. Up until now, such a pressure regulator has typically included a valve arrangeable to limit the amount of fuel passing out of the regulator and into the common rail and a solenoid actuator configured to control the position of the valve. The position of the valve (and hence the rate of flow of fuel out of the pressure regulator) is proportional to the amount of current supplied to the solenoid actuator. One issue with these pressure regulators is that they are not capable of precisely controlling fuel pressures in the common rail both when very low fuel pressures are needed therein (i.e. , when the engine is in low demand e.g., when the engine is idling) and when much larger pressures are needed therein (i.e., when the ending is in high demand). To provide both precisely, the pressure regulator has to be able to accurately alter very low flow rates e.g., around just a few tenths of grams of fuel per second (i.e. by moving the valve in the regulator by only a few microns) as well as provide higher flow rates e.g., around tens of grams of fuel per second (i.e., by moving the valve in the regulator by thousands of microns). Maintaining acceptable delivery accuracy at both ends of these ranges is therefore difficult. In particular, it is difficult to precisely provide very small changes of movements of the valve in the regulator to bring about precise changes in very low rates of fuel out of the pressure regulator. This is particularly difficult because the valves of such pressure regulators tend to experience stiction and friction that result in them moving (or “jumping”) much more than desired. It is against this background that the invention has been devised to provide an improved means of regulating pressure in the common rail of a fuel injection system. SUMMARY OF THE INVENTION According to a first aspect, there is provided a pressure regulator for a common rail of a high pressure hydrogen injection system, the pressure regulator comprising: an inlet for delivering fuel into the pressure regulator, an outlet for supplying fuel out of the pressure regulator and into the common rail, a fuel path for fuel flow between the inlet and the outlet, a valve movable between a closed position, wherein the valve is arranged to block the fuel path, and a plurality of open positions, wherein the valve is arranged to at most partially block the fuel path, each open position corresponding to a different position of the valve with respect to the fuel path, a dual-spring system arranged to urge the valve towards the closed position, the dual-spring system comprising a first spring with a first compression characteristic and a second spring with a second compression characteristic different to the first compression characteristic, and a solenoid actuator configured to draw the valve away from the closed position against the action of the dual-spring system to one of the open positions when the solenoid actuator is supplied with current, wherein the pressure regulator is configured such that: the valve is maintained in the closed position when the solenoid actuator is not supplied with current, the first spring is compressed by a first distance thereby providing a first phase of movement of the valve, when the solenoid actuator is supplied with current less than or equal to a current threshold, and the second spring is compressed by a second distance thereby providing a second phase of movement of the valve following the first phase of movement, when the solenoid actuator is supplied with current exceeding the current threshold. Each of the open and closed positions of the valve is associated with a different rate of flow of the fuel out of the pressure regulator. When the valve is closed, the rate of fuel flow out of the pressure regulator is zero. The more open the valve is, the more f