Fuel injection device for diesel engines

Claim 2

In a Diesel fuel injection device having a nozzle needle operative to open and close an injection orifice, the improvement which comprises control means operative to control the operation of said nozzle needle such that said nozzle needle has a first stroke in which said nozzle needle is moved from a first position where said nozzle needle closes said injection orifice to a second position where said nozzle needle is lifted a predetermined distance, a second stroke in which said nozzle needle is kept in said second position for a predetermined time period, a third stroke in which said nozzle needle is lifted from said second position to a third, maximum lift position, and a fourth stroke in which said nozzle needle is moved from said third, maximum lift position to a fourth position where said nozzle needle again closes said injection orifice.

Claim 3

A Diesel fuel injection device according to Claim 1, further including a pressure accumulation piping for accumulating a high pressure fuel, a pressure chamber for containing a pressure to be applied to said nozzle needle, and a control valve for changing over the pressure in said pressure chamber between a high fuel pressure from said pressure accumulation piping which forms a high pressure side of said device and a low fuel pressure in a low pressure side of the device, said control valve being adapted to be operated to actuate said nozzle needle so that the fuel from said pressure accumulation piping is injected through said injection orifice.

Claim 4

A Diesel fuel injection device according to Claim 2, wherein said control means comprises a valve means disposed in said pressure chamber.

Claim 5

A Diesel fuel injection device according to Claim 3, wherein said valve means comprises first and second valve members arranged for relative sliding movement, said first and second valve members cooperating together to divide said pressure chamber into a back pressure chamber and a control chamber, said back pressure chamber and said control chamber being com­municated with each other through a restriction passage.

Claim 6

A Diesel fuel injection device according to Claim 4, wherein said first valve member is biased by a resilient member and movable against said resilient member when the high pressure chamber is introduced into said pressure chamber by said control valve to allow the high pressure fuel to flow into said control chamber.

Claim 7

A Diesel fuel injection device according to Claim 4, wherein said second valve member is adapted to be engaged by said nozzle needle when said nozzle needle is lifted a predetermined distance, the pressure in said control chamber acting on said second valve member in a direction to move said nozzle needle in a direction to close said injection orifice.

Claim 8

A Diesel fuel injection device according to Claim 4, wherein said restriction passage is formed in said first valve member.

Claim 9

A Diesel fuel injection device according to Claim 6, wherein said second valve member has formed therein a communication groove for communicating said control chamber with a space which is defined in said pressure chamber by an outer periphery of said nozzle needle and said second valve member when said nozzle needle is lifted.

Claim 10

A Diesel fuel injection device according to Claim 6, wherein said second valve member has its outer periphery disposed in sliding engagement with an inner peripheral surface of said pressure chamber, the high pressure fuel in said control chamber being introduced into said back pressure chamber only through said restriction passage when said nozzle needle is lifted.

Claim 11

A Diesel fuel injection device according to Claim 4, said restriction passage is formed in said second valve member.

Claim 12

A diesel fuel injection device according to Claim 6, wherein said second valve member has a flange adapted to be engaged with a shoulder formed in said pressure chamber and a sliding portion slidable in a cylinder in which said nozzle needle is slidably received, said flange having formed therein a communication groove for communicating said control chamber with a space defined in said pressure chamber by an outer periphery of said sliding portion and said flange when said nozzle needle is lifted.

Claim 13

A Diesel fuel injection device according to Claim 2, wherein a restriction is provided in a passage extending between said control valve and said pressure chamber.

Claim 14

In a Diesel fuel injection device having a nozzle needle operative to open and close an injection orifice to allow a fuel from a pressure accumulation piping to be injected through said injection orifice, the improvement which comprises means for controlling the injection rate characteristic such that the injection has a first characteristic that the injection rate is substantially constant for a predetermined time period, a subsequent second characteristic that the injection rate is gradually increased from said first character­istic, and a subsequent third characteristic that the injection rate is suddenly decreased from said second characteristic.

Claim 15

In a Diesel fuel injection device having a nozzle needle operative to open and close an injection orifice to allow a fuel from a pressure accumulation piping to be injected through said injection orifice, the improvement which comprises means for controlling the injection rate characteristic such that the injection has a first characteristic that the injection rate is substantially constant for a predetermined time period, a subsequent second characteristic that the injection rate is gradually increased from said first character­istic, and a subsequent third characteristic that the injection rate is suddenly decreased from said second characteristic.

Claim 16

A Diesel fuel injection device according to Claim 13, further including a pressure accumulation piping for accumulating a high pressure fuel, a pressure chamber for containing a pressure to be applied to said nozzle needle, and a control valve for changing over the pressure in said pressure chamber between a high fuel pressure from said pressure accumulation piping which forms a high pressure side of said device and a low fuel pressure in a low pressure side of the device, said control valve being adapted to be operated to actuate said nozzle needle so that the fuel from said pressure accumulation piping is injected through said injection orifice.

Claim 17

A Diesel fuel injection device according to Claim 14, wherein said control means comprises a valve means disposed in said pressure chamber.

Claim 18

A Diesel fuel injection device according to Claim 15, wherein said valve means comprises first and second valve members arranged for relative sliding movement, said first and second valve members cooperating together to divide said pressure chamber into a back pressure chamber and a control chamber, said back pressure chamber and said control chamber being communicated with each other through a restriction passage.

Claim 19

A Diesel fuel injection device according to Claim 16, wherein said first valve member is biased by a resilient member and movable against said resilient member when the high pressure chamber is introduced into said pressure chamber by said control valve to allow the high pressure fuel to flow into said control chamber.

Claim 20

A Diesel fuel injection device according to Claim 16, wherein said second valve member is adapted to be engaged by said nozzle needle when said nozzle needle is lifted a predetermined distance, the pressure in said control chamber acting on said second valve member in a direction to move said nozzle needle in a direction to close said injection orifice.

Claim 21

A Diesel fuel injection device according to Claim 16, wherein said restriction passage is formed in said first valve member.

Claim 22

A Diesel fuel injection device according to Claim 18, wherein said second valve member has formed therein a communication groove for communicating said control chamber with a space which is defined in said pressure chamber by an outer periphery of said nozzle needle and said second valve member when said nozzle needle is lifted.

Claim 23

A Diesel fuel injection device according to Claim 18, wherein said second valve member has its outer periphery disposed in sliding engagement with an inner peripheral surface of said pressure chamber, the high pressure fuel in said control chamber being introduced into said back pressure chamber only through said restriction passage when said nozzle needle is lifted.

Claim 24

A Diesel fuel injection device according to Claim 16, wherein said restriction passage is formed in said second valve member.

Claim 25

A Diesel fuel injection device according to Claim 18, wherein said second valve member has a flange adapted to be engaged with a shoulder formed in said pressure chamber and a sliding portion slidable in a cylinder in which said nozzle needle is slidably received, said flange having formed therein a communication groove for communicating said control chamber with a space defined in said pressure chamber by an outer periphery of said sliding portion and said flange when said nozzle needle is lifted.

Claim 26

A Diesel fuel injection device according to Claim 14, wherein a restriction is provided in a passage extending between said control valve and said pressure chamber.

Claim 27

In a Diesel fuel injection system which includes a pressure accumulation piping for accumulating a fuel at a high pressure and an injector including a nozzle needle slidably disposed to open and close an injection orifice, a pressure chamber for containing a pressure acting on said nozzle needle, and a control valve operative to change over the pressure in said pressure chamber between a high fuel pressure in a high pressure side of the system formed by said pressure accumulation piping and a low fuel pressure in a low pressure side of the system, said control valve being adapted to be operated to actuate said nozzle needle so that the fuel in said pressure accumulation piping is allowed to be injected through said injection orifice, the improvement which comprises a control chamber provided to contain a part of the high pressure in said pressure chamber and control means operative to communicate said control chamber with the low pressure side of the system through a restriction passage when said control valve has changed over the pressure in said pressure chamber from the high pressure to the low pressure, said control means being further oeprative to cause the pressure in said control chamber to act on said nozzle needle when said nozzle needle is lifted a predetermined distance.

Claim 28

In a Diesel fuel injection system which includes a pressure accumulation piping for accumulating a fuel at a high pressure and an injector including a nozzle needle slidably disposed to open and close an injection orifice, a pressure chamber for containing a pressure acting on said nozzle needle, and a control valve operative to change over the pressure in said pressure chamber between a high fuel pressure in a high pressure side of the system formed by said pressure accumulation piping and a low fuel pressure in a low pressure side of the system, said control valve being adapted to be operated to actuate said nozzle needle so that the fuel in said pressure accumulation piping is allowed to be injected through said injection orifice, the improvement which comprises a control chamber provided to contain a part of the high pressure in said pressure chamber and control means operative to communicate said control chamber with the low pressure side of the system through a restriction passage when said control valve has changed over the pressure in said pressure chamber from the high pressure to the low pressure, said control means being further oeprative to cause the pressure in said control chamber to act on said nozzle needle when said nozzle needle is lifted a predetermined distance.