Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D1/00—Controlling fuel-injection pumps, e.g. of high pressure injection type
  • F02D1/16—Adjustment of injection timing
  • F02D1/18—Adjustment of injection timing with non-mechanical means for transmitting control impulse; with amplification of control impulse
  • F02D1/183—Adjustment of injection timing with non-mechanical means for transmitting control impulse; with amplification of control impulse hydraulic
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D1/00—Controlling fuel-injection pumps, e.g. of high pressure injection type
  • F02D1/16—Adjustment of injection timing
  • F02D1/18—Adjustment of injection timing with non-mechanical means for transmitting control impulse; with amplification of control impulse

Definitions

• the invention is based on a fuel injection pump for internal combustion engines according to the preamble of claim 1.
• Such a fuel injection pump is already known from DE-OS 32 01 914.
• this fuel injection pump has an adjusting piston which is arranged displaceably in a cylinder against a restoring force and delimits a working space in the latter.
• a control slide is arranged displaceably against a return spring which is supported in the cylinder by means of an adjustable support.
• the control slide delimits a pressure chamber in the blind bore, which is permanently connected to a fuel-filled suction chamber with a pressure-controlled, pressure-dependent chamber for supplying the pump work chamber of the fuel injection pump.
• the control slide Actuated by the pressure in the suction chamber, the control slide executes a speed-dependent actuating movement, the working chamber being connected to the pressure chamber or to a relief chamber, depending on the position of the control slide, or keeping the working chamber closed.
• the adjusting piston leads out of a one that closes the working space Position after appropriate pressurization or relief of the work area from a movement following the control slide, which is ended by closing the work area again. Accordingly, an adjusting movement of the adjusting piston is carried out in the direction of an earlier or later injection time.
• the support of the return spring of the control slide can be adjusted by an actuator.
• the servomotor requires a large installation space.
• pressure fluctuations in the suction space of the fuel injection pump affect the timing of the injection.
• the fuel injection pump according to the invention with the characterizing features of claim 1 has the advantage that further operating parameters of the internal combustion engine are taken into account when controlling the supply pressure and no additional space-consuming and complex actuating device is required to take account of the further operating parameters.
• the supply pressure is generated in a simple manner and independently of the pressure prevailing in the suction space of the fuel injection pump.
• the embodiment according to claim 4 enables the working space to be filled quickly after the start of operation of the fuel injection pump with low fuel consumption in order to set the control pressure, and thus an exact setting of the injection timing which starts early.
• the development according to claim 8 enables the injection point to be set even earlier for starting the internal combustion engine when the fuel injection pump starts, since a control pressure is set primarily before a speed-dependent pressure is built up in the suction chamber.
• the embodiment specified in claim 7 provides a very simple to implement, reliably operating control of the start of injection without having to make any significant changes to a fuel injection pump of the generic type.
• FIG. 1 shows a schematic illustration of a fuel injection pump with a first exemplary embodiment
• FIG. 2 with a second exemplary embodiment
• FIG. 3 with a third exemplary embodiment.
• a fuel injection pump of a known type has an adjusting piston 11 which engages via a pin 10 in a cam drive of the fuel injection pump (not shown) for the adjustment of the injection time.
• the adjusting piston 11 is displaceable in an injection adjusting cylinder 12 against the force of a return spring 13 and limits there a working space 14 filled with fuel brought to a variable control pressure a line 16 is relieved.
• a control slide 18 is displaceably arranged, which is acted upon by a second return spring 19 in the injection adjusting cylinder 12 parallel to the return spring 13 and delimits a pressure chamber 21 in the front end of the blind bore 17 .
• the control slide 18 has a supply channel 22 extending from its end face delimiting the pressure chamber 21, the opens into a first annular groove 23 serving as a control opening in the outer surface of the control slide 18, and a relief channel 24 which starts from its end face facing the relief chamber 15 and opens into a second second groove 26 serving as a control opening.
• the adjusting piston 11 has a channel 27 which extends from its end face which delimits the working space 14 and which opens into the blind bore 17.
• a transverse bore 28 extends from the blind bore 17, which opens into a longitudinal groove 29 in the lateral surface of the adjusting piston 11.
• the longitudinal groove 29 is connected to a groove 31 in the injection adjustment cylinder 12, into which a supply pressure line 42 opens, which is constantly connected to the transverse bore 28 via the longitudinal groove 29 and the groove 31, regardless of the longitudinal position of the one secured against rotation by the pin 10 Adjusting piston 11.
• the pressure chamber 21 is connected to the transverse bore 28 and thus to the supply pressure line 42 via the supply channel 22 and the first annular groove 23.
• the working space 14 can either be connected to the supply pressure line 42 via the channel 27 and the first annular groove 23, or can be connected to the relief space 15 via the second annular groove 26 and the relief channel 24, or by the two ⁇ rule the first and the second annular groove lying outer surface of the control slide 18.
• the fuel injection pump has a feed pump 33 which is driven in proportion to its drive speed and which draws fuel from a fuel tank 34 and delivers it into a feed pump pressure line 36.
• a suction chamber 38 of the fuel injection pump is filled with fuel via the feed pump pressure line 36 and a pressure holding valve 37.
• the pressure in the suction chamber 38, from which the pump working chamber of the fuel injection pump is supplied with fuel, is controlled by a pressure control valve 39, through which Material can flow back to the suction side of the feed pump 33, controlled depending on the speed.
• the pressure holding valve 37 in the delivery pump pressure line 36 opens at a lower pressure than that which is controlled by the pressure control valve 39.
• a non-return valve 41 opening to the interior 38 is arranged parallel to the pressure control valve 39.
• a pressure line 42 in which a throttle 43 is arranged, branches off from the feed pump pressure line 36 upstream of the pressure-maintaining valve 37.
• An outflow line 44 branches off downstream of the throttle 43 from the pressure line 42, which leads to the injection adjustment cylinder 12.
• a solenoid valve 46 is arranged in the outflow line 44, through which the outflow line 44 to the suction side of the feed pump 33 can be relieved.
• the solenoid valve 46 is controlled by a control unit 47 as a function of operating parameters relevant to the start of injection of an internal combustion engine operated by the fuel injection pump, such as, for example, load, temperature or acceleration.
• the solenoid valve 46 controls the pressure prevailing in the supply pressure line 42 as a control pressure to a value which lies between the pressure generated by the feed pump 33 and the pressure prevailing on the suction side of the feed pump 33.
• the position of the control spool 18 is determined by the control pressure, and at the same time it serves as an actuating medium for tracking the adjusting piston 11.
• the control spool 18 As the control pressure increases, the control spool 18 is displaced out of the blind bore 17 and the working space 14 from the first through the annular groove 23 Control pressure is applied so that the adjusting piston 11 is displaced against the force of the return spring 13, wherein it adjusts the injection timing in the "early" direction. After a certain distance, the adjusting piston 11 traverses the first annular groove 23, so that the working space 14 is no longer connected to the supply pressure line 32 and thus the adjusting movement of the adjusting piston 11 is stopped and the injection timing is no longer adjusted.
• the control slide 18 When the control pressure drops, the control slide 18 is pushed into the blind bore 17 by its return spring 19 and the working space 14 is connected to the relief space 15 via the second annular groove 26 and the relief channel 24, so that fuel flows out of the working space 14.
• the adjusting piston 11 is displaced by the return spring 13 in the direction of a later injection point in time until the adjusting piston 11 passes over the second annular groove 26 again after a certain distance and the working chamber 14 is separated from the relief chamber 15.
• the supply pressure is independent of the pressure in the suction chamber 38, since it is decoupled from it by the throttle 43, so that changes in pressure in the suction chamber 38 do not fundamentally affect the injection timing adjustment. If only a speed-dependent injection timing adjustment is desired, the solenoid valve 46 remains closed and the control pressure is determined by the suction chamber pressure.
• the pressure-maintaining valve 37 in the feed pump pressure line 36 provides an early, relatively high pressure for an early adjustment of the injection time when the internal combustion engine starts when the fuel injection pump starts, since the pressure-maintaining valve 37 only opens to the suction chamber 38 at a certain pressure.
• the suction chamber 38 can be filled with fuel by the check valve 41.
• a throttle 143 corresponding to the throttle 43 is arranged in the supply channel 122.
• the throttle in the pressure line 42 is then omitted.
• the pressure chamber 121 delimited by the control slide 118 is connected via a bore 151 in the adjusting piston 111 and grooves 152 and 153 in the adjusting piston 111 or injection adjusting cylinder 112 to the outflow line 144, in which the solenoid valve 146 is again arranged.
• a displaceable adjusting piston 211 is again shown in an injection adjusting cylinder 212, which delimits the working space 214 with one end face in the injection adjusting cylinder and the relief space 215 with its other end face, in which the return spring 213 of the adjusting piston is arranged.
• the control slide 218 is arranged in the blind bore 217 and, loaded by the return spring 219, encloses the pressure space 221 in the blind bore 217 on the end face.
• the channel 227 leading to the working space 214 is in turn controlled by the control slide.
• control slide connects the channel 227 via an annular groove 223 to the transverse bore 228 in the adjusting piston or via the annular groove 226 via the relief channel 224 in the control slide to the relief chamber 215 two ring grooves 223 and 226 closed.
• the transverse bore 228 opens at the outlet from the actuating piston 211 into the suction chamber 238 of the distributor fuel injection pump, which is supplied by the pump 233 with fuel that is under speed-dependent pressure, additionally controlled by the pressure control valve 239
• Pressure chamber 221 is connected directly to the suction chamber 238 via a connecting line 55 which runs in the adjusting piston 211 and contains a throttle 56.
• Relief line 58 in the adjusting piston opens into an annular groove 59 in the injection adjuster cylinder 212, which is connected to the relief chamber 215 via a further part 60 of the relief line.
• Solenoid valve 246, which is controlled by control unit 247, is arranged in part 60 of the relief line.
• the pressure chamber 221 is thus supplied directly from the suction chamber 238, which serves as a control pressure source.
• the throttle 56 has a decoupling function, so that the pressure in the pressure chamber 221 can also be changed in addition to the speed dependence of the control pressure in the suction chamber 238, with the aid of a targeted relief via the solenoid valve 246, which is preferably actuated in a clocked manner.
• an analog valve is also conceivable here.
• control slide 218 is thus displaced counter to its return spring 219, the adjusting piston 211 following this movement, controlled by the ring grooves 226 and 223, by setting a corresponding actuating pressure in the working chamber 214 until the channel 227 is closed again in the end position reached.
• connecting line 55 and an additional relief line 58 in the adjusting piston 211 it is also possible to use only one line 58, the connecting line 55 is omitted and instead a connection opens between the annular groove 59 and the solenoid valve 246 via a throttle 256 connected to the suction chamber 238 Line 255 in part 60 of the relief line, as shown in dashed lines in Figure 3.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

Family

ID=25887728

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (2)

Citations (5)

• 1990
  • 1990-05-22 DE DE4016462A patent/DE4016462A1/de not_active Withdrawn
  • 1990-10-25 DE DE90915093T patent/DE59004353D1/de not_active Expired - Fee Related
  • 1990-10-25 KR KR1019910700841A patent/KR0174251B1/ko not_active IP Right Cessation
  • 1990-10-25 WO PCT/DE1990/000812 patent/WO1991008386A1/de active IP Right Grant
  • 1990-10-25 ES ES90915093T patent/ES2049048T3/es not_active Expired - Lifetime
  • 1990-10-25 JP JP2514115A patent/JP3040464B2/ja not_active Expired - Fee Related
  • 1990-10-25 EP EP90915093A patent/EP0456772B1/de not_active Expired - Lifetime

Patent Citations (5)

Non-Patent Citations (1)

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