US2189705A - Airplane engine control - Google Patents

Description

Feb. 6, 1940. M E CHANDLER 2,189,705

AIRPLANE ENGINE CONTROL I Filed May 2, 1938 2 Sheets-Sheet 1 Feb. 6, 1940. M. E. CHANDLER AIRPLANE ENGINE CONTROL Filed May 2, 1938 2 Sheets-Sheet 2 wm nu INVENTOR. /A 70A/ C////oz m,

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ATTORNEY.

Patented Feb. 6, 1940 UNITED sTA'ri-:s

vPATENT orllcif:-

2,189,705 AIRPLANE ENGmE coN'rnoL Milton E. Chandler, Detroit, Mich.

Application May 2, 1938, Serial No. 205,543

4 claims.

.This invention relates to the control of the throttle of an airplane engine. It is desirable in the control of an airplane engine that vwhen the pilot has once determined the throttle position he requires for the speed at which he desires to climb, this speed be maintained at varying altitudes. Hence there should be a controLwhich would automatically open `the throttle as the .plane climbs to a higher altitude. Therefore, the pressure created by the supercharger should be maintained at some constant figure. This control should be modified, however, by the fact that at higher altitudes, back pressure decreases and therefore, for a given pressure of the supercharger a greater horse power is formed at higher altitudes than at lower altitudes.

It is also desirable that the throttles should automatically assume the position for cruising whenever the control mechanism fails.

It is also desirable that the throttle should be in the proper position for re-starting after the engine has been stopped than it is when the ignition circuit has been opened.

Itis desirable, too, to relieve the pilot of manual eiort and for this purpose I propose to make use of the oil pressure created by an oil pump driven by theengine, and to supplement this oil pump by a manually operated oil pump.

In the drawings: y

Figure 1 shows one form of my invention in which the carburetor and supercharger are indicated diagrammatically andthe control device itself is shown in cross sectionalelevation.

Figure 2 shows this device ln elevation when viewed sideways.

Figure 3 shows a more elaborate control in which the device is located in the Icockpit and the power is transmitted from the cockpit to the throttle hydraulically.

Describing Figure 1, H shows the entrance for the high pressure oil which is connected through an oil pipe M9 with the outlet from the oil pump |60. From the entrance I0 the oil iiows immediately to an annular oil chamber and from |l| it ows through the stationary sleeve ||2 to an annular chamber 3. A movable inner sleeve H13 is mounted to slide inside vthe stationary sleeve l2 and is so formed as to control the ports |05 and l H6 of the sleeve H2. For example, when the sleeve I Iltis moved to the left from the neutral position illustrated, oil ows through the' port H5 through the port lll, tothe left hand side of the piston l I8 in the cylindrical chamber H.A

`The oil pressure acting on the left hand side (Cl. 12S- 103) of the piston ||8 pushes the 'throttle control rod |20 to the right and thus opens the throttle |29 through the following mechanism (see Figure 2) 'I'he rod |20 engages with the pin |33 mounted on the bell crank lever |5|. This bell crank lever is mounted on the pin |53 which, in its turn, is mounted on the bracket |69. -This bell crank lever |5| is connected through the link |30 with the lever |41 which is mounted on the throttle shaft controlling' the throttle |29. The throttle is thus opened by the admission of the oil pressure to the left hand side of the piston IIB. The movement of the sleeve ||4 is controlled by a spring A|2| and the pressure of this spring |2| in its turn, is controlled by the eccentric |22 which is controlled by the manually operated lever |23. When the lever |23 is moved to the right in a clockwise direction, the eccentric |22 is moved to the left. 'I'he pin |6| is thus moved to the left, carrying with it the lever |54 which has a fulcrum |55 which is mounted in the metallic element |56 carried by the evacuated bellows |51, which bellows contains the spring |58. `This bellows is 'subjected to atmospheric pressure through the opening |59 in the cover |65.

In the event that it is desired not to correct the throttle opening for the back pressure variations with altitude, a lset screw |60 is provided which will lock the piece v| 56 in place. Assuming, therefore, for the moment, that the fulcrum |55 of the lever |54 is stationary, then as the throttle lever |23 moves to the right, the pin |6| moves to the left, and carries with it the pin |62 which pulls the spring housing |63 to the left. This reduces the pressure of the spring |2| on the valve ||4. The valve ||4 then moves to the left under the influence of a spring |25 contained in an evacuated bellows |24 which is mounted in the housing |26, which housing is provided with a cover |68. This housing communicatesthrough the pipe |21 with the pressure side of the supercharger |28. Hence, having placed the throttle control lever in any given position, the variations in atmospheric pressure created by the supercharger-move the valve ||4 into the position which will create a constant pressure in the suhand side'of the piston H8.

If the reverse happens, and the plane descends to sea level, when the atmospheric pressure increases the supercharger pressure also increases.

Therefore, the pressure in the housing |26 increases. The bellows |24 then collapses and the spring |2| pushes the valve ||4 over to the right. Thereupon the port ||6 is now put in commumcation with the annular chamber ||3 and the oil pressure ows through an opening |45 in a tubular spacer through the port |43 to the right hand side of the piston ||8 and the throttle rod |20 is returned to its original position. When that happens the port is put in communication with the port |36 in the hollow valve ||4. The oil then escapes from the left hand side of the piston ||8 through the port ||1, through the port |46, through the port H5, through the port |36, through the port |31, through the chamber |38 in the casting |64 and so out through the return pipe |39 to the suction side of the oil pump |40.

When the piston I8 is moving to the right, the oil escapes from the chamber ||9 through the port |43, through the port |45, through the port ||6,` through the port |44, through the hollow valve ||4, through the port |31, into the chamber |38, and so, as before, out through the return pipe |39 to the suction side of the oil pump |40.

In order to provide a seal between the high pressure oil and the low pressure oil, four rubber grummets |1|, |12, |13, |14 are provided at each end of the spacers .carrying the ports |45 and |46. These grummets engage with the outer surface of the stationary sleeve I2. The left hand casting |64, the middle casting |66, and the right hand casting containing the chamber |26 and the bracket |69 are bolted together by bolts (not shown) and the four grummets |1I, |12, |13 and |14 are thus compressed by the cylindrical spacers carrying the ports |46 and |45. Therefore, a tight joint is made preventing the oil leaking along the tube ||2.

When the throttle is opened by the movement of the rod |20, the port |4I admits oil into the center of the hollow piston rod |20 as otherwise a vacuum would be formed therein. The leakage of oil past the rod |20 is` limited by the spring loaded piston packing |10. Any leakage of oil into the chamber |26 is also limited by the spring load packing |61. Any oil which escapes by the valve ||4 escapes down the port |35, the port |42, and so to the oil outlet |39. Any oil that escapes past the piston rod |20 also flows down the port |42 as it is prevented from escaping to the atmosphere by reason of the spring loaded packing and also by the fact that the pump |40 maintains a suction through the pipe |39 in the port |42. Therefore, there is a tendency for the leakage to be inwards rather than outwards, and this is true of the chamber |26.

In an emergency it is desirable to take over the control by hand and to disengage the entire servo-mechanism from the throttle control linkafge |5|, |30, |41. To accomplish this conveniently, I provide (see Figure 2) a handle |32 on the bell crank lever |5|. A spring |34 pulls .the pivot |53 over to the right and holds the pin |33 in engagement with the slot |52 of the piston rod |20. If the lever |5| is slid over to the left the pin |33 is disengaged from the slot |52. Then the control of the throttle is taken away from the automatic hydraulic means shown and the ordinary manual control takes its place.

Remote controls In Figure 3 a more elaborate device is shown'. Portions of the drawings are designated by the letters A, B, C and D. A corresponds tothe throttle control valve ||4 and the controls therefor, shown in Figure 1; B corresponds to the piston 8, cylinder ||9, and the piston rod of Figure l; C corresponds to the throttle controls |5I, |30, |41; and D corresponds to the oil pump |40 of Figure 1.

The pump is intended to represent diagrammatically an engine driven oil pump. The other oil pump may be manually operated. The oil pump and also the manually operated pump deliver oil through the pipe 33 to the outside of the perforated sleeve 53. It then flows through an opening 54 in an inner sleeve 55. A movable tube I0 acts as the control valve and is provided with a conical face. This valve controls the communication of the high pressure oil from the pipe 33 to the port 42 in the sleeve 55. The valve |0 is adapted to be moved up and down, but when it is in the neutral position shown, the high pressure oil then has no access through the opening 42 to the throttle control mechanism designated by the letter B.

When the valve -|0 descends under the influence of the spring |08, the oil pressure causes oil to flow through this opening 42, through the perforated sleeve 56, past the shut off valve I5 which is controlled by the manually operated lever |6. At this point, the oil may escape through a safety relief valve (not shown) which communicates with the outlet of the oil from the valve I5 through a valve 43 controlled by a lever 44. This valve is shown closed and the valve I5 is shown open, which is the normal position. Under these circumstances, the oil may then take one of two paths-through the upper pipe |1, or through the lower pipe |8. These pipes are of considerable length as the part designated by the letter A is adapted to be mounted in the cockpit adjacent to the pilot, whereas the part designated B is located on the engine adjacent to the throttle.

The reason for having two pipes is that if either of them breaks, the other is automatically disconnected without permitting any oil to escape. This is accomplished by means of two identical valves 39, 39 which are balanced between similar springs 40, 40. If either pipe breaks the pressure in that pipe immediately falls and the valves 39 move in the direction of the broken pipe, sealing it off, and the other pipe will then proceed to function as though no break had occurred.

When oil under pressure is admitted through the pipes |1 and I8 (Fig. 3) to the lower larger cylinder 36, the piston 2| immediately moves over to the right. This motion carries the'piston rod 4| away from the stop 34 against which the piston 2| is pressed by the spring 22 and against which it is held firmly until the pressure on the piston 2| overcomes the pressure o f the spring 22. Anoil return pipe 16 insures that the oil pressure behind the piston 22 shall be low and removes the oil leaking past the piston 2|.

When the oil pressure fails, the spring 22 immediately restores the piston 2| to its original position, thatis, with the piston rod 4| pressing against the stop 34. At the same time, the spring 24 in the upper smaller cylinder 66 acting on the smaller piston 23 attempts to move the piston rod 6| over to the left, so that the ing position.

.3| on the other end of the throttle lever 30v 'Ihis is insured by the following means: A pin engages with a wide slot in the piston rod 4|. Hence when the piston 2| moves to the left on the failure of the oil pressure, the `throttle lever 30 is partially rotated, being pulled by the rod 4| acting against the' pin 3| and against the action of the spring 24, until the throttle lever 30 assumes the position marked Cruising on Figure 3. To attain-this result, it is necessary that the spring 22 be arranged to be more powerful than the spring 24, assuming that the lever arms of the lever 30 are equal. 'I'he plane then can be flown and landed with the throttle held in the cruising position automatically.

A broken vertical line will be noticed immediately to the right. of the pin 3| when the pin 3| is in the cruising position. This indicates the position of the piston rod 4| when the piston rod 4| engages with the stop 34'. When oil pressure is restored to the system, the .larger piston 2| immediately assumes the position shown in the drawings (Figure 3) and the smaller piston assumes the position also shown in the drawings. This is the position for wide open throttle; As more and more oil pressure is admitted the piston 23 moves further and further to the right until at last itv passes the cruising position and .the throttle assumes idling position, when the pin 3| engages with the left hand wall of the slot in the piston rod 4|. Under normal conditions, therefore, the movement of the piston 23 has complete control of the position of the throttle. The larger piston 2| and its slotted piston rod 4|` are merely provided for use in an emergency in the event that the oil pressure fails when by having this large piston 2| and the slotted piston rod 4| we can insure that the throttle is placed into the cruising position.

It will also be noticed that when the maximum pressure is admitted, the throttle is in the idle position so that excessive oil pressure cannot change the adjustment of the throttle, the intermediate positions of the throttle vbeing controlled by reduction in oil pressure.

The control valve |0 is moved by the manually controlled lever |00 as follows: The lever |00 controls the eccentric |02 which raises the link |03 which, in its turn, raises the pin 50 and lever 49, as mentioned in the description of Figure l. The clockwise movement of the manually controlled lever |00 thus reduces the prescharger (not shown) through the pipe I4. The.

supercharger pressure in the chamber 41 acts on the exhausted bellows 46 mounted in the chamber 41. Hence when the pressurerises in 41 the valve l0 falls. Leakage of oil into the chamber 41 is prevented by the spring loaded packing 65. The oil pressure is allowed to escape from the cylinder 36 to the suction side of the oil pump Il when the valve Il moves UP underthe influence of a decreased pressure in the chamber 41. I'he oil then escapes through I the port 42, through a port 10 in the hollow valve I0. It then ows through the port 1| in the tube 55, through the passage 12 to the oil outlet 13, to the return pipe 14 to the suction side of the oil pumps As before, in order to correct for the variations of backpressure, the exhausted bellows |06 is provided, supported internally by a spring |01 and mounted inside the hollow casting 62 which communicates with the atmosphere through the opening |0|. This hollow bellows |06 carries the pin |05 which has an opening with which engages the ball |04 on the end of the lever 40. Variations in atmospheric pressure thus control and modify the opening of the throttle lever 30. In the event Iis connected in the ignition circuit through the terminals 21, 21. When the circuit is broken the solenoid no longer supports the rod 25 which descends under the 'iniluence of the spring 29 and engages with the slot 26 in the rod 6|. 'I'he throttle will then be locked in a position in which the engine will reach about 800 R.. P. M. which I have found the desirable throttle setting for restarting the engine.

In the event that the ignition is cut with the throttle in the idling position, that is to say, with the piston 23 over to the right, the pin 25 would then not engage with the slot 26. In that case the valve 43 is opened slightly and sufficient oil allowedto drain out to permit the piston 23 to move slightly to the left when thepin 25 drops into the slot 26 and the throttle is then held in this position regardless of any leakage of oil that mayl take place during the time the engine is not running.

The features to which my-invention pertains are as follows: i

A servo mechanism operated by oil pressure whereby the pilot can operate the throttle with the least possible effort.

A servo mechanism in which when the throttle A servo mechanism in which, when the throt tle control lever is placed in any given position during a climb the throttlekwill automatically open as the pressure of the atmosphere decreases.

and as the atmospheric pressure increases durf ing a descent, the throttle will be closed automatically.

Automatic means for correcting for the reducti'on in backpressure which causes a slight increase in powerA for the same supercharger l pressure. l

To provide means whereby the throttle automatically assumes the cruising position in the' event that the servo mechanism fails due to any loss of oil pressure. y

To insure that the throttlesare held in the correct position for re-starting the engineA after the ignition has been cut. To provide means whereby the more or less A; delicate servo mechanism may be located in the e cockpit and the operating pistons of the throttle controls may be located on the carburetor and the operating pistons may .be connected with the servo mechanism by means of two pipes, both transmitting hydraulic pressure to the operating pistons, and arranged so that either of them can break and. the remaining pipe will continue to function despite the failure of the other pipe.

What I claim is:

1. In an airplane engine having an electric ignition system, an air entrance, a throttle valve therein, automatic throttle control means comprising a source of uid pressure, a cylinder, a piston therein, means connecting said piston with said throttle, a slide valve, manual means for moving said slide valve, a port controlled by said slide valve communicating with said cylinder, said port being adapted to apply the fluid pressure to said cylinder to move said throttle, electro-magnetic means inoperative when lthe ignition system is operative, said electro-magnetic means being adapted when the ignition circuit is open to engage with said piston to hold said piston in a position in which the throttle is in the position for starting the engine.

2. In an airplane engine having anair entrance, a throttle valve therein, automatic control means therefor comprising a source of fluid pressure, a throttle control lever, two cylinders, a piston in each cylinder, one piston having a one-way connection with said throttle lever, the other piston being permanently connected to the said throttle lever, a passage connecting the source of fluid pressure to said cylinders, manual means for controlling the application of iiuid pressure to said cylinders, the permanently connected piston being adapted to close thev throttle on an increase in pressure, the other piston being adapted to close the throttle through the oneway connection to the cruising position on a failure of the fluid pressure, and spring means adapted to move both pistons against the application of iiuid pressure.

3. In an airplane engine having a supercharger, an air entrance leading thereto, a throttle valve therein, automatic means for operating the throttle valve comprising means responsive to the absolute pressure created by said supercharger, a slide valve adapted to be operated by said meansa spring,r also engaging with said slide valve, manually operated means for varying the load on said spring, a cylinder, a piston therein, a port controlled by said slide valve communicating with said cylinder, means interconnecting the piston and the throttle, a source of oil pressure, said port being adapted to apply the oil pressure to said cylinder to move said throttle in one direction when the valve is in one position and to permit the oil to escape from said cylinder when the Valve is in another position and in which the operating cylinder is located adjacent to the throttle valve and remote from said automatic throttle control means, and two pipes are provided connecting the throttle control means with the operative cylinder, spring loaded shut oif valves located at each end of each of said connecting pipes, said valves being adapted to be held in the open position by the pressure in said pipes and to be closed by said springs on failure of the pressure.

4. In an air-plane engine having a supercharger,- an air entrance leading thereto, a throttle valve therein, automatic means for operating the throttle valve comprising means responsive to the absolute pressure created by said supercharger, a slide valve adapted to be operated by said means, a spring also engaging with said slide valve, manually operated means for varying the load on said spring, a cylinder, a piston therein, a port controlled by said slide valve communicating with said cylinder, means interconnecting the piston and the throttle, a source of oil pressure, said port being adapted to apply the oil pressure to said cylinder to move said throttle in one direction when the valve is in one position and to permit the oil to escape from said cylinder when the valve is in another position, an emergency control means comprising an auxiliary cylinder, said .auxiliary cylinder being responsive to the oil pressure, a one-way connection between the piston rod and the throttle control, spring means for moving the piston against the action of the oil pressure, a one-way connection between the piston rod and the throttle control means adapted to close the throttle, whereby on failure of the oil pressure the throttle rod is automatically placed in the cruising position.

MILTON E. CHANDLER.

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