DUAL-FUEL SUPPLY SYSTEM FOR DIRECT INJECTION

Abstract

A dual-fuel supply system (100) for direct injection for engines of heavy vehicles, comprising: a supply line of a combustible liquid (160); a supply line of a combustible gas (170); a plurality of injectors (150) in fluid communication with the supply line of the combustible liquid (160) and with the supply line of the combustible gas (170); a pressure regulator device (1) for regulating the combustible gas; an electronic control unit (ECU) configured to control the supply of combustible liquid and of the combustible gas to the injectors (150), the electronic control unit (ECU) being configured to control the pressure regulator device (1) to track a reference pressure (p.sub.target) according to a feedback logic.

Claims

1-8. (canceled)

9. A dual-fuel supply system (100) for direct injection for engines of heavy vehicles, comprising: a supply line of a combustible liquid (160); a supply line of a combustible gas (170); a plurality of injectors (150) in fluid communication with the supply line of the combustible liquid (160) and with the supply line of the combustible gas (170); an electronic control unit (ECU) configured to control the supply of the combustible liquid and of the combustible gas to said injectors (150); a pressure regulator device (1) comprising a means for establishing a selective communication between an inlet channel (2) and an outlet channel (3), said pressure regulator device (1) being configured to receive combustible gas at an inlet pressure (pin) through said inlet channel (2); a first pressure transducer (171) configured to detect the pressure of the combustible gas in the corresponding supply line (170) and to provide to said electronic control unit (ECU) a first signal (51) that is representative of the pressure detected for said combustible gas; a second pressure transducer (161) configured to detect the pressure of the combustible liquid in the corresponding supply line (160) and to provide to said electronic control unit (ECU) a second signal (S2) that is representative of the pressure detected for said combustible liquid, characterised in that said electronic control unit (ECU) is configured to generate a command signal (Scom) in response to the first signal (51) and to the second signal (S2) according to a feedback logic wherein the outlet pressure (pout) of the pressure regulator device (1) tracks a reference pressure (ptarget), said means for establishing the selective communication comprising an electro valve (4) configured to receive the command signal (Scom), said pressure regulator device (1) being configured to dispense the combustible gas from the outlet channel (3) to the supply line of the combustible gas (170) with an outlet pressure (pout) lower than the inlet pressure (pin) in response to said command signal (Scom).

10. The dual-fuel supply system (100) according to claim 9, further comprising: a third pressure transducer (131) configured to detect the pressure of the combustible gas in said inlet channel (2) and to provide to said electronic control unit (ECU) a third signal (S3) that is representative of the pressure detected for said combustible gas.

11. The dual-fuel supply system (100) according to claim 9, wherein said command signal (Scom) is also a function of a third pressure value p3 of the combustible gas detected in the inlet channel (2).

12. The dual-fuel supply system (100) according to claim 9, wherein said electro valve (4) is of the proportional type.

13. The dual-fuel supply system (100) according to claim 12, wherein said electro valve (4) comprises: a valve body (14) provided with a hole (6) interposed between the inlet channel (2) and the outlet channel (3); a shutter (5) housed in said hole (6); a solenoid (7) operatively active on said shutter (5) to move it within said hole (6) in such a way that the shutter (5) assumes a position in which the flow rate of the combustible gas passing through the hole (6) is proportional to the current that flows in the solenoid (7).

14. The dual-fuel supply system (100) according to claim 9, further comprising: a discharging channel (8); a venting valve (9) placed on the discharging channel (8) and configured to establish the selective communication between said discharging channel (8) and said outlet channel (3).

15. The dual-fuel supply system (100) according to claim 9, further comprising a shut-off valve (20) placed on said inlet channel (2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further characteristics and advantages of the present invention will become more apparent from the indicative and thus non-limiting description of a preferred but non-exclusive embodiment of a dual-fuel supply system for direct injection, as illustrated in the attached drawings, in which:

[0035] FIG. 1 schematically illustrates a dual-fuel supply system for direct injection with, according to a known solution;

[0036] FIGS. 2a to 2c schematically illustrate three embodiments of a dual-fuel supply system for direct injection, according to the present invention;

[0037] FIGS. 3-4 illustrate a pressure regulator device for regulating a combustible gas used in the direct injection dual-fuel supply system, in two different sectioned perspective views.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0038] With reference to FIGS. 2a-2b, number 100 indicates a dual-fuel supply system for direct injection, in particular for engines of heavy vehicles, i.e. for vehicles with engines typically with a capacity greater than 3 litres.

[0039] The dual-fuel supply system 100 comprises: [0040] a supply line 160 of a combustible liquid, in particular diesel (indicated below for simplicity purposes as “diesel line”); [0041] a supply line 170 of a combustible gas, in particular natural gas (indicated below for simplicity purposes as “gas line”); [0042] a plurality of dual channel injectors 150.

[0043] In particular, the dual channel injectors 150 are configured to simultaneously inject diesel and natural gas into a combustion chamber (not illustrated) of the engine.

[0044] Such injectors are of the known type and will not be described further. The dual-fuel supply system 100 comprises a pressure regulator device for regulating the pressure of the combustible gas, such device being indicated with number 1.

[0045] The components upstream of the pressure regulator device 1 are identical to those of the prior art.

[0046] In particular, with reference to FIGS. 2a-2b, the following are identified: [0047] a first tank 10 containing liquefied natural gas; [0048] a pump 11 downstream of the first tank 10; [0049] a vaporizer 12 for making the liquefied natural gas evaporate; [0050] a second tank 13 containing the vaporized natural gas.

[0051] As can be noted from FIGS. 3-4, the pressure regulator device 1 of the combustible gas comprises: [0052] an inlet channel 2 configured to receive the combustible gas at an inlet pressure p.sub.in; [0053] an outlet channel 3 configured to dispense the combustible gas at an outlet pressure p.sub.out lower than the inlet pressure pin; [0054] an electro valve 4 interposed between the inlet channel 2 and the outlet channel 3, which is configured to establish selective communication between such channels 2, 3.

[0055] According to one embodiment, the inlet pressure p.sub.in is comprised between 300-320 bar and the outlet pressure pout between 140-290 bar.

[0056] According to another embodiment, the inlet pressure p.sub.in is greater than 500 bar and the outlet pressure pout can reach up to 490 bar.

[0057] The electro valve 4 is configured to receive a command signal S.sub.corn which is a function at least of a first pressure value p.sub.1 of the combustible gas detected in the outlet channel 3, which is connected to the gas line 170.

[0058] According to the embodiment illustrated in FIGS. 2a and 2b, the command signal S.sub.corn is also a function of a second detected pressure value p.sub.2 of the combustible liquid detected in the diesel line 160. Preferably, the command signal S.sub.corn is also a function of a third detected pressure value p.sub.3 of the combustible gas detected in the inlet channel 2.

[0059] The dual-fuel supply system 100 comprises an electronic control unit ECU, which is configured to control the supply of the combustible liquid and of the combustible gas to the dual channel injectors 150.

[0060] The command signal S.sub.corn for the electro valve 4 is generated by the electronic control unit ECU.

[0061] In response to the command signal S.sub.corn, the pressure regulator device 1 dispenses the combustible gas at the outlet pressure p.sub.out.

[0062] The system 100 comprises at least one first pressure transducer 171 configured to detect the pressure of the combustible gas (indicated above as “first pressure p.sub.1”) in the corresponding gas line 170 and to provide to the electronic control unit ECU a first signal Si representative of such pressure.

[0063] In the embodiment illustrated in FIGS. 2a and 2b, the system 100 also comprises a second pressure transducer 161 configured to detect the pressure of the diesel (indicated above as “second pressure p.sub.2”) in the corresponding diesel line 160 and to provide to the electronic control unit ECU a second signal S.sub.2 representative of such pressure.

[0064] Preferably, there is also a third pressure transducer 131 configured to detect the pressure of the combustible fuel (indicated above as “third pressure p3”) in the inlet channel 2 and to provide to the electronic control unit ECU a third signal S3 representative of such pressure.

[0065] The electronic control unit ECU is configured to generate the command signal S.sub.corn in response at least to the first signal S.sub.1.

[0066] Preferably, the electronic control unit ECU is configured to generate the command signal S.sub.corn also in response to the second signal S.sub.2 and to the third signal S.sub.3 according to a feedback logic such for which the outlet pressure p.sub.out of the combustible gas from the pressure regulator device 1 tracks a reference pressure p.sub.target.

[0067] The reference pressure p.sub.target can vary as a function of the engine operating conditions.

[0068] The feedback logic implemented by the electronic control unit ECU for generating the command signal S.sub.corn perfectly considers also engine parameters such as, for example: [0069] revolutions per minute (RPM) [0070] lambda λ (AFR, air fuel ratio) [0071] engine load (aspirated air flow rate).

[0072] As can be understood from the figures and the above explanation, it is not necessary to bring the combustible liquid directly to the pressure regulator device 1, which instead only responds to the command signal S.sub.corn.

[0073] FIG. 2a relates to an embodiment in which the electronic control unit ECU is a single electronic module that acquires the engine parameters and the three signals mentioned above S.sub.1, S.sub.2, S.sub.3 and generates the command signal S.sub.corn.

[0074] FIG. 2b relates to a variant in which the control unit ECU comprises two distinct modules: a first electronic module 180 which acquires the engine parameters and sends them to a second electronic module or driver 181 (that can possibly be integrated into the pressure regulator device 1) which receives as inputs also the three signals S.sub.1, S.sub.2, S.sub.3 mentioned above and generates the command signal S.sub.corn.

[0075] FIG. 2c relates to a further variant in which the control unit ECU comprises two distinct modules: a first electronic module 180 which acquires the engine parameters and which receives the three input signals mentioned above S.sub.1, S.sub.2, S.sub.3 and generates a control logic signal S.sub.com_log to be sent to a second electronic module or driver 181 (that can possibly be integrated into the pressure regulator device 1) which generates the command signal S.sub.corn.

[0076] Preferably, the electro valve 4 is of the proportional type. In particular, it comprises: [0077] a valve body 14 inside which a hole 6 is obtained, interposed between the inlet channel 2 and the outlet channel 3; [0078] a shutter 5 housed in the hole 6; [0079] a solenoid 7 operatively active on the shutter 5 to move it within the hole 6 in such a way that it assumes a position for which the flow rate of the combustible gas passing through the hole 6 is proportional to the current that flows in the solenoid 7.

[0080] The pressure regulator device 1 also comprises a discharging channel 8 with which a venting valve 9 is associated to establish the selective communication of the discharging line with the outlet channel 3. In that case, there are two control signals, one for the electro valve 4 and the other for the venting valve 9. In general, there may be various control signals present if there are various valves to be controlled in the device 1. In particular, when the outlet pressure pout of the combustible gas exceeds a predefined threshold, the venting valve 9 is opened, so as to enable the discharge of part or all of the combustible gas through the discharging channel 8.

[0081] The discharging channel 8 leads directly into the environment or into the first tank 10 containing the liquefied natural gas.

[0082] Preferably, there is a shut-off valve 20 on the inlet channel 2 which represents a safety valve configured to interrupt the fluid communication between the inlet channel 2 and the outlet channel 3 in response to certain operating conditions of the system 100.

[0083] For example, the shut-off valve 20 intervenes in the event of the engine being turned off, or when the system operates only with diesel or in the event of an accident.

[0084] From the description provided the characteristics of the dual-fuel supply system for direct injection according to the present invention are clear, as are the advantages.

[0085] As the supply system proposed performs electronic regulation of the gas pressure the fluid connection to the diesel supply line is eliminated. The injector supply system is more flexible as the regulator is instructed by the control unit to track a reference or target pressure that may be variable (unlike what happens in completely mechanical solutions).