Summary of the Prior Art A variety of methods and devices are known for assisting in adjusting the timing of fuel injection in internal combustion engines. Timing of fuel injection is particularly critical in diesel engines where combustion may begin the instant fuel is admitted into the cylinder. Nonetheless existing timing methods and devices for assisting and adjusting injection timing are incapable of providing an accurate indication of the actual moment of injection relative to piston position while the engine is operating.

Existing devices and methods can generally be classified as dynamic timing methods which operate while an engine is running, or as static timing methods where the engine is stationary or only slowly rotated (for example by hand).

Dynamic timing methods and devices are intended to reveal actual injection timing relative to piston position but results seem subject to significant variation. One prior art device has a transducer clamped over the outside of a fuel injection line.

Output of the transducer drives a strobe timing light. The transducer is intended to detect fuel pulse timing by detection of vibration in the fuel line. The inventor has determined that the pulse timing measured by this system does not consistently relate to the timing of actual fuel pulses delivered to the cylinder. This is reflected in the wide variation of timing advance angles that are considered correct, with different angles given for each engine with which the system can be used, and with these angles not consistently corresponding with other optimal timing measures for those engines. The need for additional information to use the transducer device with each engine is considered a major inconvenience.

Another dynamic timing device has a light sensor formed to replace a glow plug of the primary cylinder. This device picks up the flash of fuel exploding in the cylinder and drives a strobe timing light in response to these flashes. One of the difficulties with this device is that it will only work in engines that are firing. This device also proves inaccurate if prevailing engine conditions do not lend themselves to instantaneous combustion as the fuel is admitted into the cylinder. This may for example be the case where the engine or prevailing atmospheric conditions are cold or engine compression is inadequate.

A third dynamic timing device is described in US patent 4,397, 180. This device includes a modified poppet valve injector. An injector in the engine is removed and the modified injector is inserted in its place. The modified injector includes an electromagnetic sensor built into the injector body. The electromagnetic sensor detects operation of the poppet valve. The output of the electromagnetic sensor is used for analysing fuel injection performance as input to an oscilloscope or as an input in a full feedback controlled fuel injection system. This device is not a practical proposition for the varied workload of most diesel mechanics. As there are a wide range of injector designs the mechanic would need to have a correspondingly wide range of modified injectors for placing in the engine. Furthermore the electromagnetic signal is not readily useable for the mechanic to determine timing without further comparison and analysis.

The-static timing methods include"spill"timing, "dial gauge"timing and"lock up"timing.

Spill timing starts with the steps of disconnecting the fuel injector line from the fuel pump for the specified cylinder to be timed, removing the delivery valve holder (which may require a special tool), removing the delivery valve and spring (and stop peg if fitted), replacing the delivery valve holder (screwing it tight onto the delivery valve seat) and connecting a fuel supply line to the fuel pump inlet. The engine crankshaft is turned back from top dead centre on the compression stroke by approximately 90 degrees. With the fuel supply turned on at low pressure (gravity flow or from a primer pump) the crankshaft is slowly turned forward in the normal engine rotation direction until the fuel flow is reduced to single drops at approximately 10 second intervals (or as

specified by the engine manufacturer). This is called spill cutoff and indicates the point of commencement of fuel injection. The crankshaft position is then checked by comparison of the timing marks on the front pulley or flywheel with the datum mark on the crank case.

Dial gauge timing involves placing a dial gauge into the pump assembly and measuring the pump plunger lift. The pump plunger lift is usually from 0.5 to 2.0 millimetres. The point of lift may not be the actual injection timing, depending on whether the pump has any prestroke in the design. The engine is hand rotated back from top dead centre position on the compression stroke by approximately 90 degrees. It is then hand rotated to TDC. At TDC the dial gauge is read to measure the lift measurement of the pump plunger. This measurement is compared with the lift measurement recommended by the engine manufacturer. The dial gauge method is often difficult due to access constraints in the modem compact engine compartment.

Lockup timing can only be used on very small diesel engines or on fuel pumps when they are disconnected from the engine. Without a special gauge, the method relies on feeling the resistance to rotation of the crank or pump shaft. The fuel pressure is a component of this resistance. The method involves turning on and priming the fuel supply to the pump, disconnecting the fuel injector line from the fuel pump for the specified cylinder to be timed, placing a small steel ball on the delivery valve holder of the fuel pump and replacing the fuel injector line. The fuel injector line is tightened lightly onto to the steel ball to block the fuel path. The engine crankshaft is turned back from TDC position on the compression stroke by approximately 90 degrees. With the fuel supply turned on at low pressure the crank shaft is slowly turned in the normal direction of engine rotation until fuel flow resistance is felt. This is called lockup and is the point of commencement of fuel injection. The resistance can be difficult to feel, in which case a high pressure gauge may be fitted to the fuel pump outlet and the point of movement observed. The crankshaft position can then be checked by comparing the timing marks on the front pulley or flywheel with the datum mark on the crank case.

The disadvantage of static methods in general is that they don't give an accurate picture of injection timing when the engine is running. The static methods are subject to

variation due to wear in the injection system which is difficult to compensate for. None of the static methods can be used to check the correct operation of variable timing systems as applied in most modern diesel engines, which vary the advance angle of injection relative to piston top dead centre (TDC) in accordance with engine operating parameters.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a timing device and method which at least goes some way towards overcoming the above disadvantages or which will at least provide technicians with a useful choice.

In a first aspect the invention may broadly be said to consist in a timing device comprising : a first member including a fuel chamber, an inlet to said fuel chamber adapted for connection with a diesel fuel line, and an outlet from said fuel chamber; a valve member biased to close off said outlet and adapted to open said outlet under increased fuel pressure in said chamber; a valve member movement detector, detecting an opening movement of said valve member and providing an output indicating opening of said valve member; a collection reservoir fitted over said outlet to receive and collect fuel ejected through said outlet; and a strobe lighting arrangement receiving said output from said valve member movement detector and providing a light pulse synchronised with an immediate response to each valve member opening event.

In a second aspect the invention may broadly be said to consist in a timing device comprising : a first member including a fuel chamber, an inlet to said fuel chamber adapted for connection with a diesel fuel line, and an outlet from said fuel chamber;

a valve member biased to close off said outlet and adapted to open said outlet under increased fuel pressure in said chamber; a valve member movement detector, detecting an opening movement of said valve member and providing an output indicating the opening of said valve member; and a strobe lighting arrangement receiving said output from said valve member movement detector and providing a light pulse synchronised with an immediate response to each valve member opening event.

In a third aspect the invention may broadly be said to consist in a timing device comprising : a first member including a fuel chamber, and inlet to said fuel chamber adapted for connection with a diesel fuel line, and an outlet from said fuel chamber; a valve member biased to close off said outlet and adapted to open said outlet under increased fuel pressure in said chamber; and a valve member movement detector, detecting an opening movement of said valve member and providing an output indicating the moment of opening of said valve member; a collection reservoir fitted over said outlet to receive and collect fuel ejected through said outlet.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional side elevation of a timing device according to the preferred embodiment of the present invention.

Figure 2 is a schematic drawing representing an electrical arrangement for converting the output of the timing device of Figure 1 to a strobe timing output.

DETAILED DESCRIPTION The present invention provides a timing device for diesel engine fuel injection.

The device includes a fuel pulse detector, and an associated electrical arrangement driving a strobe light. The strobe flashes directly correspond with fuel injection timing from the fuel injection pump, and fuel injection timing can be read directly from the timing marks adjacent to the front pulley or flywheel.

Referring to Figure 1 in the preferred embodiment of the present invention the fuel pulse detector is driven directly by pressure pulses delivered from the primary or timing cylinder fuel line. The detector is a body 1 with a central bore 2 extending along one axis there through. A pintle 3 is fitted within the bore 2 and is reciprocal along the axis of the bore. A fuel chamber 4 is formed in the body 1. The fuel chamber 4 surrounds the forward end 7 of the pintle 3. The body 1 includes a fuel line connection point 10 for receiving the fuel line connector for the primary cylinder fuel line. A fuel supply passage 5 extends from the connection point 10 to the fuel chamber 4. An outlet passage 6 extends from the fuel chamber 4, exiting the forward end of the main body 1.

The forward end 7 of pintle 3 extends into the opening 6.

The forward end 7 of the pintle 3 includes a series of reductions in diameter in the forward direction. A narrow portion 12 extends fully into the outlet opening 6 of the body 1. A midportion 14 extends up to the opening 6, and a transition 16 at the forward end of midportion 14 seats against the annular wall 20 of the opening 6. A frustoconical expansion 1 extends between the midportion 14 and the rear portion 22 of pintle 3.

The pintle and body assembly is, in essence, a standard pintle type injector assembly. Considerable variation in the actual form of pintle and body may be made without affecting its performance.

A fuel collection reservoir 21 is fitted to the forward end of the body 1. The fuel collection reservoir receives fuel from the outlet opening 6 and collects it for later disposal. Optionally the received fuel could be continuously drained off.

The body 1 includes an outward flange 32 at its rearward end. A mounting bracket 30 is fixed to the body 1 below the flange 32. The mounting bracket 30 extends to the rearward of the body 1 to locate a support member 34 a fixed distance from the rearward face 36 of the body 1. The support member 34 includes a central aperture 38 with a bush 80. A rod 40 extends from the rearward end of pintle 3 and passes through the bush 80. The rod 40 is terminated with a cap 42 beyond the aperture 38. A spring retainer 44 is fitted on the rod 40. A spring 46 is located between the retainer 44 and the support member 34. The spring 46 is retained in a partly compressed condition to provide a positive pressure pushing the pintle 3 into its seated position against surface 20 of the outlet opening 6 of the body 1. The positive pressure is broadly similar to that of an operational diesel injector, for example to provide for an operating pressure of approximately 150 Bar (15 MPa). It may prove useful to have adjustable preload for the spring 46, but as the present invention does not operate as a working injector, precise matching to the engine is not required.

A pivot base 48 and a contactor base 50 extend from the support member 34 on opposite sides of the aperture 38. A contactor arm 52 is pivotally connected about a first end 54 with the pivot base 48. The contactor arm 52 extends across the aperture 38 above the cap 42 of rod 40. The contact end 56 of contactor arm 52 includes a first contact 58 which is aligned to contact a second contact 60 of contact base 50 when the contact arm 52 is in a lowered pivotal condition. The arm 52 is pivotable to a raised pivotal position where the first contact 58 is out of contact with the second contact 60.

A spring within the pivotal connection between end 54 of contact arm 52 and pivot base 48 biases the contact arm 52 into the lowered pivotal condition. The contact base 50 is preferably conductive and is provided with an earthed connection 62. A further electrical connection of lead 64 is provided with first contact 58. The further electrical connection 64 provides the output from the mechanical portion of the timing device.

The contact member 52 has a projection 66 which extends downward to abut the upper surface of cap 42.

Therefore the pivotal position of contact member 52 is controlled by the position of pintle 3. The pintle 3 is biased toward the forward end of body 1 by spring 46. In this bias position the transition 16 of the forward end 7 of the pintle seats against surface 20 of the outlet opening of the body 1 and does not permit egress of fuel from the fuel chamber 4.

In use, the device is connected to the primary cylinder fuel line. When the fuel pump increases pressure in the primary cylinder fuel line the increased pressure presses against frustoconical surface 18 and urges the pintle 3 rearward in the body 1 against the pressure of spring 46. As the fuel pressure overcomes the bias force of spring 46 the pintle 3 moves to rearward. This opens outlet opening 6, and simultaneously pushes the pivot arm 52 upward to separate contacts 58 and 60.

Referring to Figure 2 the output from the timing device, via lead 64, drives a strobe timing light 68. The electrical circuit for driving the strobe light will be described with reference to particular components however it will be appreciated that equivalent electrical circuits, and arrangements which do not use the standard automotive ignition strobe light may be equally applicable.

For the convenience of automotive engineers, in the preferred form of the invention the output from the timing device drives a standard automotive ignition strobe light. Therefore the output from the timing device drives an electrical arrangement which imitates the standard automotive ignition system, with the output of the imitation ignition system driving the strobe light 68. The output lead 64 of the detector is connected with the negative terminal of a 12 volt automotive coil 70. The negative terminal is also connected with a condenser, or capacitor, 72 which is earthed to the automotive coil body which is earthed in turn to the engine or vehicle. The positive terminal of automotive coil 70 is connected to the positive terminal 76 of 12 volt vehicle battery 78 via ballast resistor 74. A high tension lead 80 extends between the high tension terminal 82 of the automotive coil 70 and the strobe 68. The strobe 68 is also connected across the terminals of the vehicle battery 78.

With this arrangement the breaking of contact between first contact 58 and second contact 60 breaks the current in the low voltage winding of the automotive coil

70. This leads to a rapid decay of flux in the coil magnetic circuit which generates a high voltage in the high voltage winding. This high voltage is communicated to the strobe light 68 via high tension lead 80. The strobe light 68 creates a flash of light synchronous with this high voltage signal.

Shined on the timing mark 84 and the front pulley 86 (or flywheel, as appropriate for the engine concerned), the strobing light reveals a timing angle for the primary or timing cylinder. This strobe light is precisely driven by the fuel pressure increase in the fuel pressure line for the primary or timing cylinder, so the timing angle revealed by the strobing light will correspond precisely with the timing angle for injection of fuel into the primary or timing cylinder.

This invention has been described in accordance with one preferred embodiment.

But while this gives particular advantages of simplicity and directness, it will be appreciated that other arrangements for putting the invention into practice are also possible and within the scope of the invention as defined in the appended claims.

For example, the arrangement for detecting the valve member opening may be mechanical, electrical, electromagnetic, or a combination. By way of example, US 4,397, 180 discloses suitable electromagnetic systems for performing the detection.

By way of further example the arrangement for driving a strobing light is also capable of wide variation, as is the nature and operation of the strobe light itself. For example electrical output of the opening detector (for example of the contact breaker, or of an electromagnetic or eddy current sensor) may be used as input to a logic circuit to drive an electronic switch for triggering strobe pulses.

By way of still further example the present invention may take a wide variety of physical forms. The various parts may be integrated in many different combinations and arrangements. For example the electrical or electronic arrangement for driving the strobe may be housed with the valve, or housed with the strobe.