US3329133A - Regulation devices for free piston internal combustion engines - Google Patents

Description

July 4, 1967 Filed Nov. 19, 1965 P. PANHARD REGULATION DEVICES FOR FREE PISTON INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 1 BY Pau/ Pam/5am P. PANHARD July 4, 1967 REGULATION DEVICES FOR FREE PISTON INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed Nov. 19, 1965 I 5 H T N W H T Wow MW w 0 5M United States Patent 7 Claims. (a. 123-46) The present invention relates to a regulation device for a free piston internal combustion engine provided with means for reducing the flow of fuel fed to the engine when the free piston tends to move beyond an outer dead center limit position thereof.

The invention is more especially concerned with a regulation device for a free piston internal combustion engine the piston of which is rigid with the plunger or piston of a hydraulic generator or pump connected through a closed circuit with at least one hydraulic receiver or motor so as to form a hydraulic transmission.

One object of the invention is to provide a device of this kind where the engine free piston is given a substantially uniform length of stroke by regulating the rate of feed of fuel to said engine.

The present invention further relates to a regulation device for a free piston internal combustion engine the piston of which is rigid with a plunger of a hydraulic generator connected through a closed circuit with at least one hydraulic receiver to form a hydraulic transmission, such a regulation device including means for reducing the flow rate of fuel fed to the internal combustion engine when the free piston of said engine tends to move beyond an outer dead center position thereof.

An object of the present invention is to provide a device of this kind such that it determines a substantially uniform length of stroke for the free piston by exactly regulating the fuel feed flow rate, account being taken of all the factors of operation and in particular of the number of reciprocations per unit of time, of the load of the engine, and possibly of the discharge pressure of the generator.

Preferred embodiments of the present invention will be hereinafter described with reference to the appended drawings, given merely by way of example, and in which:

FIG. 1 represents, with portions shown in elevation and portions in axial section, a power plant with a hydraulic transmission made according to the invention;

FIG. 2 shows, on an enlarged scale, the regulation device of the free piston engine of FIG. 1; and

FIG. 3 shows a detail modification.

The following description will be supposed to apply to the case of a hydraulic transmission power plant for an automobile vehicle.

The system comprises the following elements:

(a) An internal combustion engine A;

(b) A hydraulic generator (or pump), preferably ineluding two opposed groups each comprising a cylinder 1, a plunger (or rod) 2, a suction valve 3 and a delivery valve 4, said hydraulic generator being driven by engine A, as it will be hereinafter explained;

(c) A receiver, or hydraulic motor, B, the intake of I, which is connected, through pipes 5, with the delivery 3,329,133 Patented July 4, 1967 "ice (e) A holding chamber E connected to each of the cylinders 1 of the hydraulic generator between valves 3 and 4 so as to receive a variable portion of the liquid delivered on every cycle from said cylinder 1, thus determining the ratio of transmission between engine A and receiver B.

The axes of the three chambers C, D and E are disposed in star-shaped arrangement about the geometrical axis of each cylinder 1 and preferably, as shown, in a plane intersecting this cylinder. In FIG. 1 the cross section plane for the upper part of the drawing is the same vertical plane and therefore shows both of the chambers D located on the right hand side and on the left hand side, respectively, whereas the cross sections corresponding to the lower portion of FIG. 1 are made, respectively for the right hand side and the left hand side, through two planes symmetrical with respect to said vertical plane and making between them an angle of so that the left hand portion shows a chamber E and the right hand portion a chamber C.

The internal combustion engine A is of the double action type and includes a single free piston 7 mounted in a cylinder 8 having two cylinder heads 9. This piston 7 carries, fixed thereto on each opposite side thereof, a plunger or rod 2 and the hydraulic generator cylinders 1 cooperating with said plungers 2 are provided in blocks 10 rigid with cylinder heads 9. The whole of cylinder 8, cylinder heads 9 and blocks 10 is arranged to be freely oscillatable about its axis in a direction opposed to that in which oscillates the whole of piston 7 and plungers 2. The internal combustion engine intake pipes are designated by reference numeral 11 and the exhaust pipes by 12, the corresponding ports being controlled by piston 7.

Each of the holding chambers E comprises a bell-shaped shell 40 and a movable or deformable partition 43 which separates the inside of said shell 40 into two chambers 41 and 42, chamber 41 being connected permanently with the portion of the corresponding cylinder 1 between valves 3 and 4, whereas chamber 42 is placed in communication, at the end of every suction stroke of plunger 2, with a source M of gas under variable pressure, in a manner which will be hereinafter explained. Deformable partition 53 consists of a membrane engaged on a perforated rigid tube 44 fixed in shell 40 coaxially therewith. Membrane 43 carries, fixed to the bottom thereof, a check valve 45 the seat 46 of which is rigid with shell 40 and is interposed between chamber 42 and gas source M. To the bottom end of tube 44 there is fixed an ogive 47 in the bottom portion of which there is provided a cylindrical housing communicating through a passage 48 with chamber 41 and accommodating a piston 48 subjected to the action of a spring 49 and bearing against the bottom of membrane 43, so that check valve 45 closes during the delivery stroke of plunger 2 as soon as the pressure of oil in chamber 41 is equal to that of the gas present in chamber 42 and reopens during the suction stroke of plunger 2.

Thus, on every cycle, the first portion of the liquid delivered by a plunger 2 is admitted into chamber 41, which causes membrane 43 to expand and compresses the gas present in chamber 42, check valve 45 being then closed. Then the respective pressures on the opposed sides of delivery valve 4 become equal. Delivery valve 4 then opens and the second portion of the liquid driven by plunger 2 is discharged past said valve 4. The power supplied to receiver B and the ratio of transmission depend upon the respective values of the two above mentioned liquid portions and therefore upon the pressure of source M. During the next suction stroke of plunger 2, the energy corresponding to the compression of gas in chamber 42 is restored to said plunger 2. Then check valve 45 reopens.

The fuel feed device of internal combustion engine A is made as follows:

On either side of piston 7 there is disposed, inside a tubular sheath 14, fixed with respect to cylinder8, a metering member 15 consisting of a rod 15a provided with two heads 15]) and 150 adapted to slide, with a limited amplitude, in fluidtight contact with the inner face of sheath 14 and with a surface in line therewith provided in a cap 16 fixed to block 10. The cross section S of the head 15b nearer to cylinder 8 is greater than the cross section s of the other head 15c and it is acted upon, on its surface farthest to said other head (on the left hand side in FIG. 2) by the pressure existing in the compression chamber 34 of cylinder 8.

A fuel feed pipe 18 for fuel under pressure, provided with a check valve 19, opens into the annular space 17 between sheath 14 and the rod 15a of metering member 15 (extending between heads 15b and 150).

Sheath 14 is located inside a tubular sleeve rigid with piston 7 and capable, when piston 7 is nearing its outer dead center position, of opening orifices 21 and 22 providedin sheath 14 so as thus to connect the annular space 17 with the internal combustion engine compression chamber 34.

Said tubular plunger 2 includes, on its inner wall, a sleeve 26 secured thereto by means of a nut 20, the inner edge of said sleeve 26 being located clearing orifices 21, 22 when the internal combustion engine piston 7 is in its outer dead center position toward the right hand side of FIG. 2. Means are provided for making fluidtight, on the one hand, the surfaces of contact (without relative sliding displacement) between the inner wall of plunger 2 proper and the outer wall of sleeve 26 and, on the other hand, the surfaces of contact (with relative sliding displacement) between the inner wall of sleeve 26 and the outer wall of sheath 14, so as thus to separate from each other the fuel circuit and the liquid transmission circuit.

In order to limit the displacement of metering member 15 with respect to fixed sheath 14, there is provided, on the one hand, at the end of the big head 15b, a flange 27 projecting to the outside of sheath 14 and, on the other hand, at the end of the small head 150, a washer cooperating with an abutment, said washer being designated in FIG. 2 by reference numeral 28a for the hydraulic generator on the right hand side and by reference numeral 28b for the hydraulic generator on the left hand side.

In order to permit the pressure existing in the compression chamber 34 of cylinder 8 to be transmitted to the big head 15b, there is provided at least one passage 31 connecting the external surface of piston 7 with the inside of tubular plunger 2, this passage being provided in an axial plane and being slightly inclined, as shown by FIG. 2, so as to open tangentially to the curved end face of piston 7.

As shown, there is further provided, in the wall of tubular plunger 2, at least one fuel injection passage 32 positioned to open opposite orifices 21 and 22 when piston 7 is close to its outer dead center position. Passage 32 may open directly into chamber 34 but preferably, as shown by the drawings, it opens into an annular turbulence chamber 33 provided in cylinder head 9 and surrounding plunger 2. Besides, the end 15d of metering member 15 may be pushed by a small spring if it is desired to reduce the pressure of the fuel arriving through pipe 18.

When the pressure has dropped in chamber 34, the pressure in pipe 18, possibly with the addition thereto of the action of the last mentioned spring, opens check valve 19 and pushes metering member 15 toward piston 7 until washer 28a comes into contact with the above mentioned abutment. There is thus admitted into annular space 17 a volume of fuel proportional to the displacement l of metering member 15, which displacement is adjusted as it will be hereinafter explained.

At the end of the movement of piston 7 toward the right, the pressure in compression chamber 34 is transmitted through passage 31 to the big head 15b of metering member 15. As soon as the movement of piston 7 and plunger 2 causes the bevelled edge of sleeve 26 to clear orifice 21, metering member 15, which was kept in position by the column of fuel enclosed in annular space 17, is released and driven toward the right by said pressure in chamber 34 until orifice 21 is closed.

A portion of said volume of fuel is injected. The injected fuel, driven by the air stream through passages 31 and 32, mixes with air in turbulence chamber 33, where it is ignited either by suitable ignition means, or, when the compression ratio is sufficiently high, by spontaneous ignition.

When orifice 22 is subsequently cleared (near the outer dead center position of FIG. 2, on the right hand side thereof), the remainder of said fuel volume is injected and, at this time, the combustion in chamber 33 reverses the direction of flow through passages 32 and 31 and causes an ignited fuel mixture to be injected into compression chamber 34 where it finds the amount of air necessary to finish its combustion.

According to a feature of the present invention, the driver, instead of directly controlling the flow rate of fuel fed to the engine to vary the power that is given off, acts upon the means for adjusting the power transmitted to receiver B, the flow rate of fuel fed to the engine being controlled by means responsive to the variation of the difference between the theoretical stroke of free piston 7 and the actual stroke thereof, the power absorbed by the receiver being greater or smaller than the power given off by the amount of fuel precedingly fed to the internal combustion engine.

According to the embodiment shown by the drawings, the powder delivered by receiver B may be adjusted by varying, by means of a pedal 50, the pressure of the gas supplied from source M. This pedal may for instance control a distributing valve capable of connecting a reservoir of gas under pressure, corresponding essentially to source M, either with the delivery of a compressor or with the atmosphere.

In order to constitute the means responsive to the difference between the theoretical stroke of free piston 7 and its actual stroke, another feature of the present invention consists in causing free piston 7 positively to drive a rod cooperating with a capacity filled with a liquid, said capacity being provide-d at one end thereof with a cylindrical blind hole 51 in line wit-h said rod and the diameter of which is equal, with a slight play, to that of said rod. Plane P in which is located the opening of this hole 51 is located in such manner that said rod penetrate into said hole 51 only when piston 7 tends to move beyond its theoretical stroke end. Finally, means responsive to the overpressure produced in said blind hole by the penetration of said rod thereinto control a part adapted to reduce the dose of fuel admitted into combustion chamber 34 during the next stroke of free piston 7.

As shown by FIGS. 1 and 2 the above mentioned rod advantageously consists of plunger 2 which, in addition to its function of piston of the hydraulic generator, also serves to control the fuel injection. For this purpose, the blind hole 51 is disposed in line with the hydraulic generator cylinder 1.

Furthermore, the above mentioned abutment adapted to come into contact with the was-her, 28a or 28b, on one side is arranged to cooperate with means responsive to an overpressure occurring in the blind hole 51 on the other side.

For this purpose, there is provided, in each of the caps 16, a cylinder 52 separated by a piston 53 into two chambers 54 and 55. Chamber .54 is connected with blind hole 51 through a channel 56, whereas chamber 55 is connected to cylinder 1 through a channel 57.

In'or-der to produce the desired return movement of piston 53 when there is no longer an overpressure in blind hole 51, use is made, as shown by FIG. 2, of a differential piston 53 provided with a single rod which is designated by reference numeral 58b on the right hand side of the system and by 58a on the left hand side. Thus, if the same pressure exists in both of chambers 54 and 55, piston 53 is pushed into the position corresponding to the minimum of volume of chamber 54. In this case, channel 57 is provided with a check valve 59 and a passage 60 of small cross section is disposed in parallel with said channel 57. In the modification illustrated by FIG. 3, use is made of a piston balanced by a double rod 58, 58c and provided with a return spring 61.

The abutment cooperating with washer 28a consists of a fork 62a integral with a lever 63a pivotable about a pin 64a fixed with respect to the corresponding cap 16.

In a likewise manner, the abutment cooperating with washer 28b consists of a fork 62b integral with a lever 63b pivotable about a pin 64b fixed with respect to the corresponding cap 16.

The lower end of lever 63a is hinged to the right hand end of a link 65a the other end of which is hinged to the lower end of a lever 66a pivoted at 67a and end of which is hinged to rod 58a.

The lower end of lever 63b is hinged to the left hand end of a link 65b the other end of which is hinged to the lower end of a lever 66b pivoted at 67b and the upper end of which is hinged to rod 58b.

When a plunger 2 is moved outwardly by one stroke of the piston 7 of internal combustion engine 7-8, a portion of the energy supplied by said stroke is accumulated in the holding chamber E corresponding to said plunger 2.

When said plunger 2 next returns inwardly, this amount of energy is given back to said plunger 2.

In other words, during the beginning of every inward stroke of said plunger 2, a portion of cylinder 1 is filled up with liquid from holding chamber E, without having to collect energy from the internal combustion engine 7-8.

As the energy available in holding chamber E at the beginning of the corresponding stroke of the internal combustion engine piston 7 (say toward the right) was determined during the preceding leftward stroke of said piston 7, it may happen that this energy, back by holding chamber E (on the left) is too great, so that the outer end of the right hand plunger 2 engages into the corresponding blind hole 51. As a consequence, the corresponding piston 53 is moved leftward, lever 66b is pivoted in anticlockwise direction, link 65b is pulled toward the right, lever 63b is pivoted in anticlockwise direction and its forked end 6212 is moved toward the left.

Anyway, when piston 7 was at the end of its stroke toward the right (approximately as shown by FIG. 2), the

the upper added to that given left hand metering member 15 was moved toward the W,

right by the pressure of fuel fed through the corresponding pipe 18. But this movement toward the right was limited by the forked end 62b which, at this time, had been moved toward the left as above explained, so that the amplitude of the subsequent sliding displacement of metering member 15 toward the left is now smaller.

Therefore if the rightward stroke of the internal combustion engine piston 7 was of too great an amplitude (i.e. if the fuel injection into cylinder 8 on the left of piston 7 had been too great), the next fuel injection on the left of piston 7 will be reduced.

If the above considered rightward stroke of the internal combustion engine piston 7 was too long, of course the next leftward stroke of said. piston was also too long (since no correction relative to fuel injection could take place between them). Therefore the left hand plunger 2 engaged the corresponding blind hole 51 and the liquid thus driven caused, through piston 53, lever 66a, link a and lever 63a the forked end 62a of said lever 63a, the stroke of the right hand metering member 15 to be shortened as the stroke of the left hand metering member 15 was shortened.

It will now be noted that the regulation effect is practcially instantaneous since the injection after too long or too short a stroke of piston 7 is substantially immediately corrected. It suflices to choose the diameter of piston 53 and the arm ratios of levers 63 and 66 in such manner that too long or too short a stroke of piston 7 (for instance by 1 mm.) produces exactly the variation of fuel injection corresponding to the difference of energy to be supplied. It will be noted also that the regulation device according to the present invention is so efficient that it remedies all possible defects since it works in accordance with the effect and not in accordance with the cause. It would be possible to adjust the injection of fuel by means of a mere needle valve disposed between a source of fuel under sufficient pressure and combustion chamber 34. Finally it is pointed out that the device according to this invention ensures perfect equality between the leftward and right-ward strokes of the double action piston without any preliminary adjustment. The diameters of the injecting device and the leakages therein are without effect upon the accuracy of compensation.

If the action on the flow rate of fuel is insuflicient to limit the stroke of piston 7, pistons 53 may be made to control a mechanism (not shown) capable of reducing the pressure of source M, that is tosay in chamber 42, independently of the position of pedal 50, so'that the torque is reduced. Such a mechanism would prevent the internal combustion engine from stalling.

In a general manner, while the above description discloses what are deemed to be practical and eflicient embodiments of the present invention, said invention is not limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the invention as comprehended within the scope of the appended claims.

What I claim is:

1. In combination,

an internal combustion engine comprising a cylinder and a piston freely slidable in said cylinder so as to form therewith two variable volume chambers located respectively on either side of said piston,

two rods rigid with said piston and coaxial therewith on either side thereof, respectively, said rods extending through the respective ends of said cylinder,

a cylindrical structure rigid with said cylinder adapted to accommodate each of said rods, slidable in said structure, said structure being filled with a liquid,

each of said structurse forming, at the outer end thereof a cylindrical blind hole in line with the corresponding rod and adapted to accommodate it with a sliding fit, said blind holes being so positioned that each of said rods engages thereinto only when the outer dead center of said piston is beyond a predetermined position,

regulatable means for feeding fuel into said cylinder in response to the reciprocating movements of said piston with respect to said cylinder,

and means responsive to overpressure produced in said blind hole when said rods engage thereinto, for operating said regulatable fuel feed means to reduce the rate of fuel feed ensured by said last mentioned means.

2. A combination according to claim 1, further comprising a hydraulic receiver, a hydraulic generator, and a closed circuit connecting said receiver with said generator so as to form a hydraulic transmission between them, said generator including cylinders, fixed with respect to said engine cylinder and plungers adapted slidably to cooperate with said generator cylinders and integral with said rods, respectively.

3. In combination,

an internal combustion engine including a cylinder and a piston freely slidable in said cylinder,

a hydraulic generator including a cylinder rigid with said internal combustion engine cylinder and a piston rigid with said internal combustion engine piston,

a hydraulic receiver,

a closed hydraulic circuit between said hydraulic receiver and said hydraulic generator,

adjustable means for feeding fuel to said internal combustion engine,

hand operative means for controlling the power delivered to said hydraulic receiver by said hydraulic generator,

and means responsive to variations of the difference between the theoretical stroke of the internal combustion engine free piston and the actual stroke thereof for controlling said fuel feeding means to reduce the fuel feed rate in response to displacements of said internal combustion engine piston beyond a limit outer dead center position thereof.

4. A combination according to claim 3 comprising a holding capacity for receiving, on every cycle of said generator, a portion of the liquid delivered by said generator and a deformable partition adapted to divide the inside of said capacity into two chambers, a first one and a second one, said first chamber being in communication with said hydraulic generator cylinder, and a source of gas under adjustable pressure adapted to communicate with said second chamber, said hand operation means being arranged to vary the pressure of said gas source.

5. A combination according to claim 3 comprising a differential sliding rod operative by variation of the difference between the theoretical stroke and the actual stroke of said internal combustion engine piston, said adjustable fuel feeding means being operative by said rod.

6. A combination according to claim 3 wherein said internal combustion engine comprises a single free piston the meains responsive to variations of the difference between the theoretical stroke of said engine free piston and the actual stroke thereof in one direction being adapted to adjust the flow rate of fuel admitted into the cylinder during the following stroke of the piston in the other direction and vice versa.

7. In combination,

an internal combustion engine comprising a cylinder having a cylinder end and a piston freely slidable in said cylinder so as to form therewith a variable volume chamber on either side of said piston,

two hydraulic generators, respectively on opposite sides of said internal combustion engine, each of said generators comprising a tubular plunger rigid with said piston and coaxial therewith, said plunger extending through the corresponding cylinder end, and a cylinder rigid with said internal combustion engine cylinder adapted slidably to accommodate said plunger, said generator cylinder being filled with a liquid,

a delivery valve connected with each of said generator cylinders,

a suction valve connected with each of said generator cylinders,

a closed hydraulic circuit extending from each of said delivery valve to corresponding suction valve,

a hydraulic receiver in said hydraulic circuits,

a liquid holding device connected with each of said generator cylinders, said liquid holding device including:

a liquid-tight shell in permanent communication with said last mentioned cylinder,

a deformable partition in said shell dividing it into two 8 chambers, a first one and a second one, said first chamber being in permanent free communication with said last mentioned cylinder,

rigid means for limiting the deformations of said partition that reduce the volume of said first chamber,

a check valve carried by said shell and opening into said second chamber, and

means responsive to the pressure in said first chamber for opening said check valve in response to a suction in said first chamber,

a source of gas under pressure, common to both of said liquid holding devices, adapted to communicate with said second chambers through said check valves,

manually operative means for controlling the pressure of said source,

a tubular casing rigid with each of said cylinder heads and extending coaxially therein, said casing including, in line with each other, a sheath, the inner end of which opens into said compression chamber and at the outer end of said sheath, a cap provided with a bore the outer end of which opens into the atmosphere,

a metering member coaxially slidable in each of said casings, said metering member including at its respective ends two heads slidable with a fluid-tight fit in said casing, to wit a big head located in the inner end of said sheath and a small head located in said cap, the cross section area of said small head being smaller than that of said big head, the portion of said metering member between said heads being a rod leaving an annular space between itself and the inner wall of said sheath,

a fuel feed pipe opening into each of said annular spaces for the feed of fuel under pressure into the corresponding sheath,

a check valve in each of said fuel feed pipes to prevent the outflow of fuel therethrough,

a sleeve rigid with each of said tubular plungers and fitting slidably about the corresponding sheath,

each of said sheaths being provided with at least one orifice and the corresponding plunger with one passage adapted, when said piston is nearing its outer dead center position, to connect said annular space in said sheath with said internal combustion engine compression chamber,

whereby each of said metering members, after being fixed in position by the column of liquid in the corresponding annular space, oan be displaced by the gaseous pressure applied on the big head thereof and thus inject into the engine cylinder a volume of fuel equal to the difference between the volumes displaced respectively by said two heads,

and means responsive to variations of the length of outward stroke of said plunger for adjusting the inward stroke of said metering member so as to reduce it when said plunger outward stroke exceeds a predetermined value.

References Cited UNITED STATES PATENTS 3,065,703 11/1962 Harman 123-46 X 3,168,045 2/1965 Sebastiani 103-37 3,199,456 10/1965 Wachsrnuth 10337 X MARK NEWMAN, Primary Examiner.

W. E. BURNS, Assistant Examiner.

Claims (1)

1. IN COMBINATION, AN INTERNAL COMBUSTION ENGINE COMPRISING A CYLINDER AND A PISTON FREELY SLIABLE IN SAID CYLINDER SO AS TO FORM THEREWITH TWO VARIABLE VOLUME CHAMBERS LOCATED RESPECTIVELY ON EITHER SIDE OF SAID PISTON, TWO RODS RIGID WITH SAID PISTON AND COAXIAL THEREWITH ON EITHER SIDE THEREOF, RESPECTIVELY, SAID RODS EXTENDING THROUGH THE RESPECTIVE ENDS OF SAID CYLINDER, A CYLINDRICAL STRUCTURE RIGID WITH SAID CYLINDER ADAPTED TO ACCOMMODATE EACH OF SAID RODS, SLIDABLE IN SAID STRUCTURE, SAID STRUCTURE BEING FILLED WITH A LIQUID, EACH OF SAID STRUCTURE FORMING, AT THE OUTER END THEREOF A CYLINDRICAL BLIND HOLE IN LINE WITH THE CORRESPONDING ROD AND ADAPTED TO ACCOMMODATE IT WITH A SLIDING FIT, SAID BLIND HOLES BEING SO POSITIONED THAT EACH OF SAID RODS ENGAGES THEREINTO ONLY WHEN THE OUTER DEAD CENTER OF SAID PISTON IS BEYOND A PREDETERMINED POSITION, REGULATABLE MEANS FOR FEEDING FUEL INTO SAID CYLINDER IN RESPONSE TO THE RECIPROCATING MOVEMENTS OF SAID PISTON WITH RESPECT TO SAID CYLINDER, AND MEANS RESPONSIVE TO OVERPRESSURE PRODUCED IN SAID BLIND HOLE WHEN SAID RODS ENGAGE THEREINTO, FOR OPERATING SAID REGULATABLE FUEL FEED MEANS TO REDUCE THE RATE OF FUEL FEED ENSURED BY SAID LAST MENTIONED MEANS.

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