2. BACKGROUND INFORMATION Figure 1 shows a fuel injector that is disclosed in U. S. Patent No. 5,460,329 issued to Sturman. The Sturman injector includes an hydraulically-driven intensifier 1 that can pressurize a fuel located within a fuel chamber 2. The pressurized fuel is ejected through one or more nozzle openings 3 in a tip 4 of the injector. The flow of fuel through the openings 3 is controlled by a spring-biased needle or check valve 5.

The intensifier 1 has a head 6 that is located within an intensifier chamber 7. The intensifier chamber 7 is hydraulically coupled to a control valve 8 which can control the flow of an hydraulic fluid into the chamber 7. The control valve 8 is typically a three-way valve which can selectively hydraulically couple the chamber 7 to either a high pressure rail line (not shown) or low pressure drain line (not shown). When hydraulically coupled to the rail line, the high pressure hydraulic fluid flows into the intensifier chamber 7 and pushes the intensifier 1 into a downward or pumping direction. The downward movement of the intensifier 1 pressurizes the fuel within the fuel chamber 2. The pressurized fuel pushes the needle valve 5 into an (upward) open position so that fuel is ejected or sprayed through the nozzle openings 3.

The injector includes a return spring 9 which pushes the intensifier 1 back to its original (upward) position when the control valve 8 hydraulically couples the chamber 7 to the drain line. The upward movement of the intensifier 1 also draws fuel into the fuel chamber 2 so that the process can be repeated. The spring-biased needle valve 5 is also pushed back into its closed (downward) position.

The return spring 9 is located within a spring chamber 10. Hydraulic fluid within the intensifier chamber 7 may leak past the outer peripheral surface of the head 6 and into the spring chamber 10. Any fluid within the spring chamber 10 may create an hydrostatic pressure which impedes or prevents the downward movement of the intensifier 1. To prevent the build-up of hydrostatic pressure, the injector 1 may contain a drain passage 11 that is hydraulically coupled to the spring passage 10. The drain passage 11 allows hydraulic fluid which leaks into the spring chamber 10 to flow out of the injector. The drain passage 11 extends along the longitudinal axis of the injector to an outlet port 12 located adjacent to the control valve 8.

The fuel injector is typically assembled into an internal combustion engine. By way of example, the fuel injector may eject diesel fuel into a diesel engine. It is desirable to reduce the size of the fuel injector to minimize the overall size and weight of the engine. The existence of the longitudinal drain passage limits the minimum diameter or cross-sectional area of the fuel injector. In addition to the diameter or cross-sectional area of the drain passage, the passage also requires an outer wall which increases the size of the injector. It would be desirable to provide a fuel injector which does not have a longitudinal drain passage.

SUMMARY OF THE INVENTION One embodiment of the present invention is an intensified fuel injector which has a side drain passage.

The fuel injector may include a valve body which has longitudinal axis. The valve body may have a fuel chamber that is hydraulically coupled to a fuel supply port and a nozzle opening. An intensifier moves within the fuel chamber. The intensifier is hydraulically coupled to an intensifier chamber and connected to a biasing spring. The spring is located within a spring chamber that is hydraulically coupled to the drain passage. The drain passage may extend through the valve body in a direction that is essentially perpendicular to the longitudinal axis of the body.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a fuel injector in the prior art; Figure 2 is a cross-sectional view of an embodiment of a fuel injector of the present invention; Figure 3 is an enlarged cross-sectional partial view taken along line 3-3 of Fig. 2 showing a control valve of the fuel injector; Figure 4 is a view similar to Fig. 2 showing the injector ejecting fuel.

DETAILED DESCRIPTION OF THE INVENTION One embodiment of the present invention is an intensified fuel injector which has a side drain passage.

The fuel injector may include a valve body which has longitudinal axis. The valve body may have a fuel chamber that is hydraulically coupled to a fuel supply port and a nozzle opening. An intensifier moves within the fuel chamber. The intensifier is hydraulically coupled to an intensifier chamber and also connected to a biasing spring.

The spring is located within a spring chamber that is hydraulically coupled to the drain passage. The drain passage may extend through the valve body in a direction that is substantially perpendicular to the longitudinal axis of the body. The orientation and location of the drain passage minimizes the diameter or cross-sectional area of the fuel injector by eliminating a longitudinal passage typically found in fuel injectors of the prior art.

Referring to the drawings more particularly by reference numbers, Figure 2 shows an embodiment of a fuel injector 100. The injector 100 includes an intensifier 102, movable between a retracted position and an extended position, that can pressurize a fuel located within a fuel chamber 104 of an injector body 106. The fuel chamber 104 is connected to a passage 108 which extends to a needle or check valve 110. The needle valve 110 controls the flow of fuel through one or more nozzle openings 112 located in a tip 114 of the injector 106. The needle valve 110 may be coupled to a return spring 116 which biases the valve 110 (downwardly) into a closed position. In the closed position, the needle valve 110 prevents fuel from flowing through the nozzle opening (s) 112. The fuel chamber 104 may also be coupled to a fuel line 117 by a fuel supply passage 118 and a one-way check valve 120.

The intensifier 102 may include a piston 122 that can move relative to the injector body 106 to either decrease or increase the volume of the fuel chamber 104. Movement of the piston 122 to decrease the volume of the fuel chamber 104 pressurizes the fuel within the chamber 104. The pressurized fuel pushes the needle valve 110 (upwardly) to an open position so that fuel is ejected from the nozzle opening (s) 112. Movement of the piston 122 to increase the volume of the fuel chamber 104 draws fuel into the chamber 104 through the passage 118 and past the check valve 120.

The piston 122 may be coupled to a return spring 124 that is captured by a cap 126. The spring 124 may bias the piston 122 to an upward or retracted position. The cap 126 is located within an intensifier chamber 128 that is hydraulically coupled to a pair of passages 130 and 132.

Hydraulic fluid may flow into the chamber 128 through the passages 130 and 132. The flow of hydraulic fluid into the chamber 128 drives the intensifier 102 into a downward or pumping direction to pressurize the fuel within the fuel chamber 104. The cap 126 has an effective area that is larger than the effective area of the piston 122 within the fuel chamber 104 so that the fuel pressure in the fuel chamber 104 is greater than the pressure of the hydraulically fluid driving the intensifier 102. A flow of hydraulic fluid out of the intensifier chamber 128 allows the spring 124 to return the piston 122 to its original or retracted position so that the cycle can be repeated.

The spring 124 is located within a spring chamber 134.

Some of the hydraulic fluid may leak across the outer peripheral surface of the ccp 126 from the intensifier chamber 128 into the spring chamber 134. To drain any fluid leakage, the injector 100 may include at least one drain passage 136 that is hydraulically coupled directly to the spring chamber 134. As shown, the drain passage 136 may extend through the injector body 106 in a direction that is substantially perpendicular to the longitudinal axis of the injector body 106. The orientation and location of the passage 136 reduces the number of longitudinal passages in the injector 100. The reduction in longitudinal passages advantageously minimizes the diameter or cross-sectional area of the injector 100.

The valve body 106 may include blocks 138,140 and 142 that are located within an outer injector housing 144. The injector housing 144 may be screwed into a valve housing 146. The injector housing 144 may have a first outer peripheral seal groove 148 and a second outer peripheral seal groove 150. The valve housing 146 may include a third outer peripheral seal groove 152 and a fourth outer peripheral seal groove 154. The seal grooves 148,150,152 and 154 typically contain O-rings (not shown) which seal the injector 100 into a cylinder head (not shown) of an internal combustion engine (not shown).

The fuel supply passage 118 may be located between the first and second seal grooves 148,150. The drain passage 136 may be located between the second and third seal grooves 150,152. One or more hydraulic fluid supply passages 156 may be located between the third and fourth seal grooves 152,154 of the valve housing 148. The valve body 146 may also have at least one drain passage 158. The fluid supply passages 156 may be connected to an external high pressure rail line 157. The drain passage 158 may be connected to an external drain line 159.

Figure 3 shows a control valve 160 which controls the flow of hydraulic fluid through the passages 130 and 132.

The valve 160 includes a spool 162 which moves within a spool chamber 164 positioned between a first coil 166 and a second coil 168. The valve 160 is electrically connected to an electronic controller 170 which can selectively provide electrical current to one of the coils 166 and 168 to move the spool 162 into one of two opposed positions.

The spool 162 has outer grooves 172 which hydraulically couple the passages 130 and 132 to the supply passages 156 when the spool 162 is in one (leftward) position. When the spool 162 is in the other (rightward) position, the passages 130 and 132 are hydraulically coupled to the drain passages 158. The spool 162 and valve body 146 may be constructed from 4140 steel which will retain enough residual magnetism to maintain the position of the spool 162 even when electrical current is not provided to the coils 166 and 168.

In this manner, the controller 170 may switch the position of the spool 162 by providing a digital pulse to one of the coils 166 or 168. The control valve 160 may be similar to the valve disclosed in U. S. Patent No. 5,640,987 issued to Sturman, which is hereby incorporated by reference.

As shown in Figure 4, in operation, the control valve 160 is switched by the controller 170 so that the passages 130 and 132 are hydraulically coupled to the supply passage (s) 156. Consequently, hydraulic fluid flows into the intensifier chamber 128 and drives the intensifier 102 in a downward or pumping direction. The movement of the intensifier 102 pressurizes the fuel within the fuel chamber 104. The pressurized fuel opens the needle valve 110 so that fuel is ejected from the nozzle openings 112.

The controller 170 then switches the valve 160 so that the passages 130 and 132 are coupled to the drain passage (s) 158. Coupling the passages 130,132 to the drain passage (s) 158 lowers the pressure within the intensifier chamber 104 such that the return spring 124 pushes the intensifier 102 back to its original or retracted position. The upward movement of the intensifier 102 also reduces the pressure within the fuel chamber 104 and pulls fuel into the chamber 104. The reduction in fuel pressure within the chamber 104 allows the return spring 116 to move the needle valve 110 back to its original closed (downward) position so that the cycle can be repeated.

The drain passage 136 directly drains any hydraulic fluid leakage, which may be present in the spring chamber 134, laterally out of the injector body 106.

While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.