underrail hydraulic pump drive shaft supplier

The main use of hydraulic rail tensors/rail pullers takes place during welding procedures.The rail tensor is used for pulling two lengths of rail together so the welding process can be performed.

In addition to single use, the tensors can be dual configured so that two parallel rail tensors can be controlled with one hydraulic power pump (sold separately, refer related products for petrol pump).

The MIT 70 SLW rail tensor is composed of two stirrups made from a special casting, eccentrics for anchoring on the rail, 2 lightweight aluminium hydraulic cylinders, 2 tie rods and 2 hydraulic hoses (requiring a hydraulic power pump to operate).The hydraulic cylinders have a security valve that doesn’t the operator to exceed the standard pressures.

Those passenger service requirements are not a step towards improving services for passengers; they are a step towards protecting the commercially most profitable routes in order to make franchises that nobody wants to buy just a bit more saleable. It is a policy driven by dogma, fuelled by endless broken promises and marked by almost universal opposition in the country. If it continues to be pursued, we shall ensure that it plays a major role in bringing about the Government"s downfall.

I always enjoy the Secretary of State"s performances. He reminds me of a small boy banging a dustbin lid in the dark to drive away the ghosties. He does it with such panache; there is no factual basis, but a lot of panache, and I do admire that.

British Rail uses a raft of excuses—"BR-speak," as I call it. For example, slugs on the line stop heavyweight carriages dead in their tracks; bridges are in a perpetual state of repairs; floods always cover the line between Taunton and Exeter, not to mention the cursed sea at Dawlish, which is always going over the tracks just beyond that town. Freak thunderstorms cause power failures in Cornwall; not only does that county seem to be in permanent darkness, but the trains are always shunted on to sidings and fleets of buses take people from one station to another to connect with other trains. Then there is the ubiquitous phantom of Westbury—the cow that is so regularly seen on the line. Whenever the train is on time, the driver stops dead because he says that there is a cow on the line. One always hears at Paddington that the delay has been caused by a cow—it is more like Bombay or Delhi than Westbury—and if there is no cow on the line, then signals, points and crossings will do the trick.

The problem with west country services is not only that the timetable has slipped but that trains arrive progressively later than the timetable time, with a difference of some 15 or 20 minutes, which produces growing anxiety in the minds of travellers that they will arrive late if they go by rail. More people are taking to the road, which is the last thing that we want as our west country roads are already saturated with cars which I suspect are driven by people who would have gone by rail but for the feeling that rail services are unreliable.

On summer weekends, a train travels from Paddington to Totnes in just under two and a half hours. It is an exhilarating journey. The train is always full to the gunnels, with people hanging out of the windows, egging the driver on. One would like to see more of that. In winter, the trains are full of depressed passengers, paying through the nose, having their tickets clipped incessantly, and drowning their sorrows in powdered coffee and tea from the buffet, or in French water and wine. Would you, Mr. Deputy Speaker, expect to find English wine or water on SNCF trains in France? Can you imagine the French serving exclusively English wine or water on SNCF? Of course not—only French wine and French water would be served. When the service is privatised, I hope that British goods, and not all that European stuff, will be served on trains because British goods are not served on French trains.

My other memory was of the branch lines for passenger services throughout the south and west, the old push-me pull-you between Salisbury and Downton or Newton Abbot and Teigngrace. In Devon, I explored the old granite tramways from Haytor to the coast and Brunel"s hydraulic railway along the coast from Starcross, where the pump house still stands. I have also extensively used trains in Germany, which, incidentally, are not all that they are cracked up to be, and I have worried my American friends by insisting on travelling by train rather than by air, for example when I undertook a 17-hour journey from Portland to San Francisco on the Starlight Express. I also saw the future on the bullet train from Osaka to Tokyo.

The hon. Member for South Hams was very concerned—as all Tories are in these Eurosceptical days—about the fact that French wine and French water are served on the trains which speed their way to South Hams. In contrast, he cares nothing about the fact that thousands of jobs will be sacrificed in the constituency of my hon. Friend the Member for York (Mr. Bayley) or that another great British industry is being driven to the wall because, as a result of the Government"s railway privatisation policy, we will soon lose the capacity to build trains in this country.

The present invention relates to solenoid operated pump-line-nozzle fuel injections systems for internal combustion engines. In particular, to such fuel injection systems in which an inline injection pump utilizes a solenoid-operated control for regulating injection timing and the quantity of fuel injected.

Inline injection pumps and pump-line-nozzle fuel injections systems using such pumps are old and well known. A discussion of several examples of such pumps and systems, and the efforts taken to improve their construction so that the increasing demands for low exhaust emissions can be met, can be found, for example, in SAE publication no. SP-703, Recent Developments in Electronic Engine Control & Fuel Injection Management, paper nos. 870433, 870434 and 870436, pages 37-42, 43-51 & 65-77 published February, 1987. Inline pumps have a separate pumping cylinder for supplying fuel to each injection nozzle of the injection system, to which it is connected by a fuel line (hence, the name pump-line-nozzle injection system), a respective injection nozzle being provided for each engine cylinder. While inline pumps, such as those described in the papers cited above, are able to independently control injection timing and injection quantity, none of the known inline pumps produces individual cylinder control of both timing and fuel quantity on an infinitely adjustable basis; that is, typically such pumps having a control rack which adjusts all pumping cylinders in the same manner at the same time, and frequently using a step-wise adjusting driver.

Another type of pump used in pump-line-nozzle systems is a distributor pump. Examples of such pumps can be found in U.K. Patent Nos. 442,839 and 1,306,422 as well as U.S. Pat. Nos. 3,035,523 and 4,502,445, and a system and component description of both inline and distributor pumps can be found at page 24 of the above-cited SAE publication SP-703 in paper no. 870432 as well. In distributor pumps, only a single pumping cylinder is provided and a rotary distributor determines which injection nozzle will receive a specific dose of fuel. Inherently, such pumps cannot provide individual cylinder control since they lack individual pumping cylinders to control; however, as indicated, e.g., in U.S. Pat. Nos. 2,947,257 and 2,950,709, such distributor pumps can be constructed as multicylinder pumps as well (but in such a case they essentially become inline pumps, with a rack, cam or other single regulating mechanism being used to control "the whole of the injectors" and to insure that fuel delivery "is the same for all the cylinders"), so that individual cylinder control is still not obtained.

Another type of fuel injection system, which is fundamentally different from pump-line-nozzle systems, is the unit injector fuel injection system. In such a system, a positive displacement pump is used to supply fuel at low pressure, typically at constant pressure of e.g., 30 psi, to a respective unit fuel injector associated with each engine cylinder. The unit injectors, themselves, regulate the timing and metering of the fuel into the respective engine cylinder and also develop the high pressure, e.g., at least 15,000 psi at which the fuel needs to be injected into the engine cycle if the requirements for increased fuel economy and decreased emissions are to be achieved.

Solenoid operated fuel injectors of the unit injector type having characteristics of the type sought to be obtained with the inline pump of the pump-line-nozzle injector system of the present invention have been in use for some time, and an example of such an injector can be found in commonly-owned U.S. Pat. No. 4,531,672 to Smith. In this type of injection, a timing chamber is defined between a pair of plungers that are reciprocatingly displaceable within the bore of the body of the injector and a metering chamber is formed in the bore below the lower of the two plungers. A supply rail in the engine delivers a low pressure supply of fuel to the injector body. To control this supply of fuel, a solenoid valve is disposed in the flow path between the fuel supply rail and the injector bore and the plungers block and unblock respective ports leading from injector body fuel supply circuit into the timing and metering chambers.

However, while unit fuel injector fuel injection systems are available by which the amount of fuel injected and timing of its injection can be independently and infinitely adjusted on a individual cylinder and cycle-to-cycle basis, using a relatively simple, single solenoid control for each injector, unit injectors, due to increased tasks associated therewith in comparison to the injection nozzle of a pump-line-nozzle injection system, is relatively large in comparison to the injection nozzle of pump-line-nozzle injection systems. As a result, the use of unit fuel injector systems has been confined to large, heavy duty engines since insufficient space exists in the engine valve area of smaller engines to accommodate unit fuel injectors. Thus, there still is a need for further improvements to pump-line-nozzle fuel injector systems of the type to which this invention is directed, in order to provide the degrees of precision control needed to meet the competing demands for both increased fuel economy and decreased engine exhaust emissions.

In another unit fuel injector system development of the assignee of the present application, which is disclosed by several of the present inventors with another inventor in co-pending U.S. patent application Ser. No. 08/208,365, a metering system for controlling the amount of fuel supplied to the combustion chambers of a multi-cylinder internal combustion engine comprises a fuel pump for supplying fuel at low pressure to a first and a second group of unit fuel injectors via first and second fuel supply paths, respectively. A first solenoid-operated fuel control valve, positioned in the first fuel supply path between the fuel pump and the first set of unit fuel injectors, controls the flow of fuel to the first set of unit fuel injectors while a second solenoid-operated fuel control valve, positioned in the second fuel supply path between the fuel pump and the second set of unit fuel injectors, controls the flow of fuel to the second set of unit fuel injectors. Only one injector from the first group and one injector from the second group of unit fuel injectors can be placed in a mode for receiving fuel from the fuel pump at any given time during the operation of the engine, thereby allowing the metering of each injector to be independently controlled over a greater time period. The system may also include a first solenoid-operated timing fluid control valve positioned in a first timing fluid supply path associated with the first group of unit fuel injectors and a second solenoid-operated timing fluid control valve positioned in a second timing fluid supply path associated with the second group of unit fuel injectors, wherein at any given time only one injector from the first group and one injector from the second group of injectors can be placed in a timing fluid receiving mode. The injectors are capable of being in the fuel receiving mode, establishing a metering period, and the timing receiving mode, establishing a timing period, at the same time to increase the amount of time available for metering both timing fluid and fuel. By grouping the various injectors based on the order of injection, so that the injectors from each group are placed in the injection mode in spaced periods throughout each cycle of the engine, e.g. injectors from other groups injecting in the period of time between each injection mode, the system can be designed to permit longer metering and timing periods.

The unit injectors may include an injector body having an injection orifice at one end and a cavity communicating with the orifice and containing inner and outer plunger sections arranged to form a variable volume metering chamber between the inner plunger and the orifice for receiving fuel during the metering period and a variable volume timing chamber between the inner and outer plungers for receiving timing fluid during the timing period. The solenoid-operated valves are moved between open and closed positions during the metering and timing periods to allow fuel and timing fluid, respectively, to flow to the metering and timing chambers thereby defining metering and timing events, respectively. The metering and timing events for each injector occur only between periodic, relatively quick injection strokes of the plungers thereby minimizing the operating response time requirements of the control valves. The fuel supply passage to the metering chamber of each injector contains a spring-loaded check valve for preventing the flow of fuel out of the metering chamber while also preventing combustion gases from entering the supply passage and disturbing the effective control of metering. The injectors may be either open or closed nozzle injectors. A pressure regulator maintains the pressure in the timing fluid and fuel supply paths at a substantially constant pressure. Also, flow control valves may be provided downstream of the fuel pump to provide a fixed flow rate independent of fuel pressures upstream and downstream of the flow control valves.

In view of the foregoing, it is an object of the present invention to provide an pump-line-nozzle fuel injector system in which an inline injection pump utilizes a solenoid-operated control for regulating injection timing and the quantity of fuel injected so as to enable the amount of fuel injected and timing of its injection to be independently and infinitely adjusted on a individual cylinder and cycle-to-cycle basis in a manner minimizing the number of solenoid valves required as well as the operating pressure and response time requirements for the solenoid valves.

In connection with the preceding object, it is a more specific object to adapt known unit fuel injector technology to the environment of pump-line-nozzle systems where the compressibility of the fuel has a significant effect due to the length of the line between the pump and the nozzle.

A still further object is to provide an inline pump in which a pair of solenoid valves control metering and timing for a group of pumping cylinders in accordance with time-pressure (TP) principles (the quantity metered being determined by the amount of time that the respective valve is open), the pumping cylinders being grouped based on the order of injection, so that only one pumping cylinder from each group is placed into an injection mode and a timing mode at any given time.

Yet another object of the present invention is to achieve the foregoing objects through the use of the cam profile of the operating cam used to drive timing and metering plungers of each pumping cylinder as the mechanism by which initiation of injection is controlled.

These and other objects are achieved in accordance with a preferred embodiment of the invention in which a low pressure supply pump is coupled to a high pressure pump having a plurality of pumping cylinders, each of which has a cam-driven timing plunger and a floating metering plunger. During the retraction stroke, flow to a timing chamber formed between the pistons is controlled by a first solenoid valve while the fuel flow into a metering chamber is controlled by a second solenoid valve. During metering, the discharge side of the pump is closed relative to a high pressure delivery line by a delivery valve. During the compression stroke, return flow is precluded by check valves in the supply lines to the timing and metering cylinders. Most importantly, since only one pumping cylinder of each pumping group undergoes its metering and injection phases at a given time, the timing and metering plungers of the other pumping cylinders being held in their maximally inwardly displaced, end-of-injection positions at that time, a single set of timing and metering solenoid valves can be used to individually meter fuel into the metering chamber and timing fluid into the timing chamber, independently and with the quantities metered being infinitely adjustable on a individual cylinder and cycle-to-cycle basis. Once the fuel is sufficiently pressurized, the delivery valve opens and the fuel is delivered to the respective injector via the high pressure delivery line from the particular one of the pumping cylinders.

FIG. 7 is a schematic diagram of a pump-line-nozzle fuel injection system of FIG. 6 showing the grouping of plural pumping cylinders with respect to respective fueling and timing solenoid valves; and

FIGS. 8a-8c are cross-sectional schematic views of a portion of the pump-line-nozzle fuel injection system of FIG. 6, showing the plunger positions and cam angles of the pumping cylinders of a first set of pumping cylinders at an engine crank angle of 0°, 120° and 240°, respectively.

With reference to FIG. 4, the pump-line-nozzle fuel injection system 10 in accordance with the parent application can be seen to be comprised of an inline high pressure pump 12 having a plurality of identical pumping cylinder units C (only one of which is shown), each of which is connected by a high pressure line 14 to a respective one of a plurality of engine fuel injectors 16 (only one of which is shown), and corresponding in number to the number of cylinders of the internal combustion engine with which it is to be used (not shown). A low pressure supply pump 18 draws fuel from a fuel supply (such as a vehicle fuel tank) and supplies the fuel to each of the pumping cylinder units C of inline pump 12, via a fuel supply circuit 20, at a pressure of, e.g., about 30 psi, which is held substantially constant by a pressure regulator 22.

Since the construction and operation of all of the pumping cylinder units C of inline pump 12 are identical, for simplicity, only the single pumping cylinder unit C shown will be described in detail, it being understood that such descriptions are not limited to only that one cylinder unit. On the other hand, it should be realized that each of the several pumping cylinder units of pump 12 is independently, individually controllable with respect to the timing and quantity of fuel caused to be injected thereby under the control of the Electronic Control Module (ECM) 24, as will be explained further below.

As illustrated, each pumping cylinder unit C comprises a timing plunger 26 and a metering plunger 28 that are reciprocatingly received in a bore of the pump 12. The timing plunger 26 is spring-loaded against a tappet 31 which rides on the periphery of a respective lobe of a pump cam shaft 33, pump cam shaft 33 being linked to the engine drive shaft to rotate in synchronism therewith. In view of the high pressures generated by the pumping unit C, e.g., approximately 15,000-18,500 psi, to at least partially compensate for the length of high pressure line 14 and the compressibility of the fuel therein, timing plunger 26 is, preferably, larger in diameter, about one-third larger, than the metering plunger 28 so as to achieve a fast pumping rate. For example, it has been found to be suitable to use a timing plunger of 12 mm diameter with a metering plunger of 9 mm.

A variable volume timing chamber 40 is defined in the bore of the pumping cylinder between the timing plunger 26 and a facing end of the metering plunger 28, and a metering chamber 42 is defined between the opposite end of the metering plunger and a delivery valve 44. The flow of timing fluid (which may be engine lubrication oil, or fuel as illustrated) into and out of the timing chamber is controlled by a solenoid valve 46, and return flow out of the metering chamber 42 is prevented by a metering check valve 48.

As the tappet 31 continues to track the curvature of the lobe of cam 33, at the end of the retraction stroke, the timing plunger is caused to move in its compression stroke toward the metering piston and the discharge end of the pumping cylinder. However, until the ECM 24 determines that the appropriate time for commencement of injection has arrived, solenoid valve 46 remains open and the fuel is forced back out of the timing chamber 40, through the solenoid valve 46 to the supply circuit 20. To prevent this outflow of fuel from affecting the supply of fuel to travel to other pumping cylinder units via their supply branches 20a, a relief valve can be provided to vent high pressure spikes from the supply side of the system 10 to the drain side thereof, such a relief valve being schematically depicted by block 52 at the manifold junction from which the branches 20a, 20b extend; however, it will be appreciated that the relief valve 52 can be placed at any of a number of other locations instead.

Once the ECM 24 determines that the appropriate time for initiation of injection has arrived, it triggers closing of solenoid valve 46, thereby trapping the remainder of the fuel serving as the timing fluid in the timing chamber 40. This trapped fuel acts as a hydraulic link between the timing plunger 26 and the metering plunger 28, and thus, causing the upward force on the timing plunger 26 to be transferred to the metering plunger 28, pressurizing the fuel in the metering chamber 42. When the pressure of the fuel in the metering chamber 42 reaches the required level, e.g., 15,000-18,500 psi, the delivery valve 44 pops open, allowing the fuel to flow from the metering chamber 42 into the high pressure line 14 and into the injector 16. Because of the nozzle spray holes are closed by a needle valve of injector 16, continued upward movement of the plungers 26, 28, causes the pressure of the fuel to increase, and when the needle valve opening pressure is reached, the fuel causes the needle valve in the nozzle of injector 16 to open, so that the fuel exits spray holes of the nozzle into the combustion chamber of the engine. However, since the nozzle holes for a flow restriction, the fuel pressure will steadily increase as injection progresses and the plungers 26, 28 are driven further into the cylinder bore by the action of the tappet 31 and cam 33.

The ECM can be of conventional design receiving various engine operating parameter inputs P1, P2 . . . Pn, such as engine speed, load, etc. and determining the appropriate times for opening and closing the solenoid valves 24 on the basis thereof and can also adjust for the compressibility of the fuel and the length of high pressure lines 14. Due to similarities between the embodiments of the parent case and the above-noted CELECT unit injector, they can share such components as the ECM, sensors and solenoid valve, and will enable service tools used with that unit injector for calibration and problem diagnosis to be used with the pump-line-nozzle system of parent case, thereby increasing its cost effectiveness, and it can be implemented on existing engines without redesign of the engine head or block. Likewise, no significant changes from the system and operation described above are needed to implement the mentioned ability to use lubrication oil as the timing fluid instead of fuel; that is, timing fluid line 50b and timing fluid drain line 58 need only be connected to the lubrication oil circuit instead of the fuel supply circuit as represent in FIG. 5 with the engine oil pump serving to supply lubrication oil to the timing chamber when the solenoid valve 46 opens.

In this context, the nature and significance of the further developments incorporated into the preferred embodiment of a pump-line-nozzle fuel injection system 10" of the present application shown in FIGS. 6-8. In the following description, emphasis is placed on the points of distinction between system 10" and system 10 in accordance with the parent application, those attributes not being described being the same, a repeated description thereof having been omitted for the sake of brevity. Accordingly, those components which remain unchanged bear the same reference numerals while those which have been modified are distinguished by prime (") designations and new reference characters being applied to components having no counterpart.

As can be seen from FIGS. 6-8, pump-line-nozzle fuel injection system 10" is comprised of an inline high pressure pump 12" having a plurality of identical pumping cylinder units C", in the example shown in FIG. 7, pump 12" (for use with a six cylinder engine, not shown) has six cylinder units C"1 to C"6, which receive fuel from a low pressure pump 18 via a supply circuit 20 containing a pressure regulator 22, and which deliver fuel at high pressure via a high pressure line 14 to a respective fuel injector 16. As also represented, the cylinder units C"1 to C"3 and C"4 to C"6 are arranged to be grouped together so that flow to them from a common fueling branch 20"a and a common timing branch 20"b is controlled by a respective fueling solenoid 46"a and timing solenoid 46"b together with a check valve 48"a, 48"b for each cylinder. This is in contrast to the case, explained above, for the embodiments of the FIGS. 4 and 5, where each cylinder unit C has a solenoid 46 in flow path 20b to each timing chamber and a check valve 48 in the flow path 20a to each metering chamber. The arrangement of FIGS. 6-8, therefore, is advantageous in that only four solenoid valves are required instead of six (offering reductions in system size, weight and cost), and these solenoids need only act on low pressure fluid (less than 300 psi) and their response time requirements can be reduced (e.g., to 2 to 12 msec).

Furthermore, unlike the case of the embodiments of FIGS. 4 and 5, where the solenoid valve 46 controls both the quantity of fuel injected and the timing at which injection is initiated, thereby requiring high sensor accuracy and high solenoid valve responsiveness, the embodiment of FIGS. 6-8, utilizes the profile of camshaft 33" to determine when injection is initiated with the quantities of timing fluid and fuel metered being controlled by the separate solenoid valves 46a, 46b under the control of the electronic control module ECM. In particular, for each group of cylinder units C"1 to C"3 and C"4 to C"6, only cylinder unit C" is active for receiving fuel and time fluid at any given time.

That is, as can be seen from FIGS. 8a-8c viewed together, as one pumping unit C", of a group of three pumping units, has completed its injection stroke (FIG. 8a), another one of the pumping units has commenced its metering phase (FIG. 8c). At the same time, the third pumping unit (FIG. 8b) remains in its fully extended, end-of-injection position, on the outer base circle of the cam surface of its cam 33". Put another way, at any given time only one pumping cylinder C" of each pumping group is in a metering and injection phase, the others being held against downward movement. In this way, the single fueling solenoid valve 46"a and the single timing solenoid valve 46"b can control flow to metering and timing chambers of all pumping cylinders C" of the group with the cams 33" controlling the initiation of injection. During injection, the check valves 48"b, 48"a serve to prevent return flows from the timing and metering chambers 40, 42 back through the solenoid valves 46"b, 46"a. Opening and closing of the solenoid valves 46a, 46, is set by the ECM on the basis of various engine operating parameter inputs, such as engine speed, load, etc. as with the embodiment of FIGS. 4 and 5, with the amount of fuel/timing fluid metered being a function of the pressure in the supply circuit 20 and the amount of time that the respective solenoid valve 46a, 46b is open while the tappet 31 and plunger 26 are descending along the metering (inwardly descending) portion of the cam surface of cam 33".

This construction and operation causes the fuel to be metered immediately before it is injected instead of over almost a full rotation of the cam, improving engine control and response time, especially at low engine speeds. Furthermore, the timing of the opening and closing of the solenoid valves relative to camshaft position becomes less critical since the valves only have to be open during the metering period; injection timing is controlled by the camshaft profile and metered quantity of fuel and not by when the solenoid is actuated (as in the embodiment of FIGS. 4 & 5). As a result, problems related to position sensor accuracy and gear train torsional effects are eliminated.