US2338761A - Centrifugal governor - Google Patents

Description

Jan. 11, 1944. DRAPER 2,338,761

CENTRIFUGAL GOVERNOR Filed Feb. 12, 1942 4 Sheets-Sheet l a FIG t; wvsmvk AD HAPE I Jan. 11, 1944" A. D. DRAPER CENTRIFUGAL GOVERNOR Filed Feb. 12, 1942 4 Sheets-Sheet 2 Jan. 11, 1944. DRAPER 2,338,761

' CENTRIFUGAL GOVERNOR Filed Feb. 12, 1942 4 Sheets-Sheet 3 Jan. 11, 1944. DRAPER 2,338,761

CENTRIFUGAL GOVERNOR Filed Feb. 12, 1942 4 Sheets-Sheet 4 Patented Jan. 11, 1944 Application February 12, 1942, Serial No. 430,697

In Great Britain March 28, 1941v 6 Claims.

This invention relates to centrifugal governors intended more particularly for controlling the speed of internal combustion engines and in which the movement of weights against a spring causes actuation of the throttle or otherwise controls the engine.

In the following description, the word strength is used as meaning the ratio of load to tension. .The tension means the degree of stretching. It is desirable to be able to adjust a governor with respect to the strength of the spring without affecting the tension, because it is commonly specified that a governor must control the engine at various speeds with a maximum variation at each speed between light load and full load. This requirement can be met by providing an adjustment for varying the strength of the spring, but such adjustment must not affect the spring tension, since the tension setting determines the speed variation between light load and full load. In at least one known arrangement in which this adjustment can be effected. it is not easy to alter the strength of the spring without afiecting the setting with respect to the tension. With this invention this defect is avoided.

According to this invention in a governor for the purpose indicated one end of the efiective part of a coiled spring is carried by a member adjustably connected to a part which takes the spring reaction and this member engages the coils of the spring on and along which it is rotatable thereby varying the strength of the spring by a1- tering the length of its operative part but withoutaltering its tension, while the other end of the spring bears on a second and separate and movable member. This second member may be adjustable by itself for the purpose of varying the tension of the spring ina manner which will prevent this tension being altered when the coils. Conveniently the pitch of the screwthread, I

which constitutes the connection between this member and the nonrotatable fixed part, is substantially the same as the pitch of the spring coils. The second member on which bears the other end of the spring engages a spindle which lies within the spring and can be moved by the weights to effect the engine control. This spindle and the driving shaft for the weights are arranged substantially coaxial, but with their adjacent ends spaced apart with a shaft-length interposed between these ends so that movement will be transmitted through this shaft-length from the weights to the spindle and so to the one end of the spring. The weights and the spring are preferably enclosed within a substantially cylindrical casing into the one end of which is screwed the first member whose adjustment varies the efiective length or. strength of the spring. The spindle on which is the member en-' gaging the other end of the spring is connected to a lever on a transverse shaft carried in bearings in a casing which surrounds the spring. A lever is fixed on one end or the other of this transverse shaft in a manner which permits the angular position of this lever about the shaft axis to be altered as may be convenient when mounting the governor on the engine. This lever serves to transmit the engine-controlling movements from the governor weights.

With this improved construction it will be seen that it is possible to vary the strength of the spring by altering its efiective length without varying the tension. Further by reason of the general construction of the casing and the arrangement of the means by which the movements are transmitted from the governor to the engine control it is possible to mount the governor in such a position as may be suitable for making the connections for the transmission of the controlling movements.

The invention may be carried into practice in various ways, but the accompanying drawings illustrate by way of example a construction which may be employed. In these drawings:

Figure 1 is a side elevation of the improved governor.

Figure 2 is a view from the lefthand end as seen in Figure 1.

Figure 3 is a longitudinal sectional elevation the section being taken on the line 3-3 in Figure 2 looking in the direction of the arrows.

Figure 4 is a transverse section on the broken line 4-4 in Figure 3 looking in the direction of the arrows,

Figure 5 is a transverse section on the line 5-5 in Figure 3.

Figure 6 is a side elevation of the modified form of lever shown at the righthand side of Figure 4, by which the control is eflected by the governor.

The driving shaft A of the governor is carried in bearings suitably arranged in the one end of a cylindrical casing B. On the outer end portion of this shaft is fixed a pulley wheel A whose size is determined in accordance with the desired speed ratio of th drive. The weights C are mounted on a collar C fixed on the inner end of the shaft A so that as they swing outwards their lever arms C will tend to transmit movement in the direction of the axis of the shaft. Into the other end B of the main part of the cylindrical casing 13 fits an extension piece D which closes that end of the casing by what is in effect a partition D beyond which the extension projects with its exterior cylindrical and its end open. In the centre of this partition D is an opening formed as a sleeve-like guide D in which can freely slide a short length of shafting E which lies coaxial with the driving shaft A and carries towards its inner end a ball race E through which the arms of the weights C can act on that end of the shaft E and impart sliding movement thereto.

In the open end of the cylindrical extension D of the casing B is a screwthread D of quick pitch and with this engages a corresponding thread F on the exterior of a short sleeve F having at its outer end an external flange F or other formation which will enable the sleeve to be rotated in the extension of the casing. In a suitable position within this sleeve F is an inwardly projecting flange F of substantial width or thickness in the axial direction and the inner part of this flange is grooved or formed as at F as a quick pitch screwthread, but the grooving is shaped to engage the coils of a spring G one extreme end G of which is anchored by inserting it in a hole D in the partition D within the casing DB. The engagement between the sleeve F and the spring coils forms a connection between the one end of the effective part of the spring G and the fixed casing D which thus takes the spring reaction. Rotation of the sleeve F will move along the coils this connection with the spring and thus alter its operative length, that is to say its strength or load.

The other, that is the outer end of the spring is formed into an eye G which engages a thimble or collar H on the outer end portion of a spindle J which extends inwards towards the outer end of the sliding shaft length E in the partition D in the casing, the spindle J and this shaft E being coaxial and their ends in effect abutting through a roller K on the end of the spindle. This end of the spindle is pivotally connected at J to a short lever arm L on a transverselydisposed shaft M carried in bearings D in the extension D of the casing (see Figures 2 and 4). By altering the position of the rotatable sleeve F which engages the coils of the spring G, the strength of the spring can be varied and this can be done without affecting the tension. If desired the tension as well as the strength of the sprin may be adjustable. The collar H is screwed on the outer end part of the spindle J though other means may be provided whereby this collar can be adjusted along the spindle. These two adjustments will not affect each other since they are at opposite ends of the spring. When the sleeve F has been adjusted it can be fixed by the set screw F Movements of the weights 0 as they swing out are communicated through the sliding shaftlength E, roller K and lever arm L to the transverse shaft M against the action of the spring G. The transverse shaft M can be arranged in its bearings D so that its end on which a lever can be fixed will project for this purpose either from one side or the other of the casing and the angular position in which the lever is fixed on the shaft may be as found convenient. This can be seen in Figure 2 where a lever N, also seen in Figure 1, is shown as fixed on the one end of the shaft M which lies on the righthand side of Figure 2. On the lefthand side of that figure a lever N' is shown in chain lines in two difierent angular positions in which it may be placed on that end of the shaft M. Owing to the cylindrical exterior of the main part B of the casing the whole governor may be clamped in place in such an angular position about its axis as may be convenient having regard to the desirable position about that axis of the axis of the transverse shaft M and the disposition of the control connections to the engine.

In a modified construction shown in Figures 4 and 6 the lever on the transverse shaft M may be articulated, that is to say the main part N of this lever which is fixed on the end of the shaft may have pivoted thereto at N an extension N. The movement of the extension in relation to the main part N of the lever may be determined by a quadrant N on the latter and over which the extension can swing between stops with a clamping nut N to fix it in the desired position. A spring N may be provided about the pivot N of the extension lever N which will tend to swing this extension in a direction which will always return it to a position against one of the stops. With this arrangement it is possible to hold the engine throttle in the correct position for starting since the extension N of the lever can be freed and swing by hand into the starting position and there clamped by the nut N After starting the extension can be released and moved by hand into its running position and again clamped so that the governor may take over the control of the engine. If the spring N is provided this may automatically return the lever extension N to its runnin position. This latter arrangement may be employed where there is a remote hand control and in that case the means for clamping the extension N to ,the main part N of the lever may be dispensed with.

With a governor constructed as described above the spring load lies on the axis of the governor and thus causes the least friction on the moving parts. As for instance the transverse shaft M is arranged so that it is not under load from the spring G.

When the weights C have swung out to their extreme positions the thrust race E through which the movements are transmitted to the sliding shaft-length E will be in such a position that the face of this ball race will come up against the end of the guide sleeve D in the partition D within the casing. The lever N on the transverse shaft M which actuates the engine control will then have been moved into the extreme position into which it can be moved by the governor. This lever, if formed with an extension N however, can be moved by hand or otherwise beyond this position as for starting in the manner mentioned above.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a centrifugal governor for controlling the speed of an internal combustion engine, the combination of a spindle with means'for driving it, weights carried by this spindle so that they will be swung outwards by centrifugal force as the spindle rotates, a. shaft member which is coaxial with the driving spindle and is movable in the axial direction by the action of the gov-' ernor weights as they fly outwards, a transmission rod coaxial with the said sliding shaft member and serving as a connection between one end of that shaft and one end of a coiled spring which lies around this spindle, a member which on the one hand engages the coils of this spring and on the other is in screwthreaded engagement with a fixed part and thus serves as an adjustable connection between the spring and this fixed part, and means for transmitting to the part controlled by the governor the movements imparted to the said sliding shaft by the weights.

2. In a centrifugal governor for controlling the speed of an internal combustion engine, the combination of a spindle with means for driving it, weights carried by this spindle so that they will be swung outwards by centrifugal force as the spindle rotates, a shaft member which is coaxial with the driving spindle and is movable in the axial direction by the action of the governor weights as they fly outwards, a transmission rod coaxial with the said sliding shaft member and serving as a cmnection between one end of that shaft and one end of a coiled spring which lies around this spindle, a member which lies around the spring and between it and a fixed part in relation to which this member is rotatable, the coils ofthe spring being engaged externally by this member which is in screw-threaded engagement with the said fixed 'part, rotation of this member varying the claim 1 the combination with the transmission rod, of means for adjusting the connection between the one end of this rod and the end of the spring whereby the tension of the spring can be varied.

4. A centrifugal governor as claimed in claim 2 in which the screwthread which constitutes the engagement between the fixed part and the rotatable member has a pitch substantially the same as the pitch of the spring coils which are engaged by this rotatable member.

5. In a centrifugal governor as claimed in claim 1 the combination of a casing enclosing the coiled spring and having a partition through which passes and by which isguided the sliding shaft member, a transverse shaft carried in bearings in the casing and lying adjacent to the cooperating ends of the sliding shaft member and the transmission rod, a lever on this transverse shaft connected to the adjacent end of the transmission rod so that the lever will be moved as and when the transmission rod is moved by the action of the governor weights, a second lever on a part of this transverse shaft which lies outside the casing, and means for transmitting the movements of this second lever to the part controlled by the governor.

6. An adjustably mounted coiled spring for use with a centrifugal governor having a casing, weights and a spindle, comprising an adjustably mounted support on the spindle movable in the direction of the length of the spindle and supporting one end of the spring in adjusted position thereby to vary the tension of the spring,

and a sleeve threaded internally and externally,

the internal threads of which coact with the convolutions of the spring while its external threads coact with the casing to change the relative point of connection of the sleeve with the spring, thereby to vary its strength.

ALICK DARBY DRAPER.

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