Field of the invention:
[0001] The present invention relates to a governor for an inline fuel injection pump.
Background of the invention:
[0002] According to a prior art US4109628, an adjustable regulation governor is disclosed. The governor mechanism for a fuel injection pump is of the type having interacting fly-weights and a main governor spring for regulating engine speed, and means are included for selectively changing the spring rate of the main governor spring to change the regulation of the governor.
Brief description of the accompanying drawings:
[0003] An embodiment of the disclosure is described with reference to the
following accompanying drawing,
[0004] Fig. 1 illustrates a first view of a variable speed governor for an inline fuel
injection pump, according to an embodiment of the present invention;
[0005] Fig. 2 illustrates a second view of the variable speed governor for an inline
fuel injection pump, according to an embodiment of the present invention, and
[0006] Fig. 3 illustrates a characteristic map of the variable speed governor,
according to the embodiment of the present invention.
[0007] Fig. 4 illustrates progressive springs used as governor spring, according to
an embodiment of the present invention.
Detailed description of the embodiments:
[0008] Fig. 1 illustrates a first view of a variable speed governor for an inline fuel injection pump, according to an embodiment of the present invention. The variable speed governor 100 comprises at least two flyweights 104 coupled to a camshaft 204 (shown in Fig. 2), a governor spring 102, and a plurality of linkages connecting the governor spring 102 and the flyweights 104. The governor spring 102 used in the governor 100 is a variable pitch spring. The variable speed governor 100 is a centrifugal governor and will be referred to as governor 100 hereinafter for simplicity. The pitch is also referred to as spring rate. The term pitch corresponds

to distance consecutive coils of the governor spring 102. Thus, variable pitch signifies different pitch between pluralities of coil of the governor spring 102.
[0009] Fig. 2 illustrates a second view of the variable speed governor for an inline fuel injection pump, according to an embodiment of the present invention. The present invention enables speed droop control in the governor 100. The governor spring 102 is pivoted design and external to the flyweights 104. When the speed is set by means of the control lever 106, the position and tension of the governor spring 102 alters in such a way that, when the engine is running at the desired speed, the turning force acting on a tensioning lever 202 is held in equilibrium by the opposing turning force produced by the flyweights 104. The governor spring 102 is connected at one end to the tensioning lever 202 and at the other to a rocker 208. All changes to the position of the control lever 106 and to the position of the flyweights 104 are transmitted to a control rack 206, through the linkages and linking mechanisms known in the art. The flyweights 104 are not shown in Fig. 2.
[0010] Fig. 3 illustrates a characteristic map of the variable speed governor, according to the embodiment of the present invention. The X-axis 302 represents engine speed in Rotation Per Minute (RPM) and the Y-axis 304 represents control rod travel/movement in millimeter (mm). The existing/conventional governor 100 is designed such that the speed droop at maximum speed and intermediate speed varies largely by 5- 10% due to use of governor spring 102 with constant spring rate or constant pitch. However, as per the present invention, the spring tension of the governor spring 102 is changed from constant/uniform spring rate to variable spring rate. The functioning of the governor 100 is based on a spring and mass balance system where the tension forces of the governor spring 102 is opposed by turning forces of the flyweights 104. This state of equilibrium defines the speed droop at the condition i.e. maximum speed or intermediate speed of the engine. By suitably altering the governor spring rates (by using variable pitch spring instead of constant pitch spring) the equilibrium state changes defining the speed droop as desired at chosen condition. The speed droop at intermediate engine speed, when

the governor spring 102 with constant spring rate is used, is shown between points 306 to 310, and 312 to 316. However, when the governor spring 102 with a variable spring rate or progressive spring rate is used, then the speed droop characteristic at the intermediate speed changes from 306 to 308, and 312 to 314. The speed droop characteristic at intermediate engine speed at points 306 and 312 becomes similar to the speed droop characteristic at maximum engine speed 318 to 320. The response is improved.
[0011] Fig. 4 illustrates progressive springs used as governor spring, according to an embodiment of the present invention. A cut-section view of a hook spring 410 is shown. The hook spring 410 is only for illustration and must not be understood in limiting manner. Similarly, a drawbar spring 420 is also applicable for being used as the governor spring 102. The hook spring 410 and the drawbar spring 420 can have variable pitches. The drawbar spring 420 in Fig 4 is just a representation and must not be understood in limiting manner.
[0012] In accordance to an embodiment of the present invention, the variable pitch spring is a progressive pitch spring. Further, the governor spring 102 with variable spring rate is a hook spring 410. The variable pitch of the governor spring 102 gives varied tension force at different extended lengths of spring coils as compared to constant pitch spring.
[0013] According to an embodiment of the present invention, the governor spring 102 provides same speed droop at maximum engine speed and intermediate engine speed conditions. Decreased speed droop gives better speed control on the engine. Flexibility to define desired speed droops at max speed and intermediate speeds for better fueling control and exhaust emissions. No major change in interfaces and pump construction required.
[0014] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such

embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

We claim:
1. A governor (100) for an inline fuel injection pump, comprising:
at least two flyweights (104) coupled to a camshaft (204);
a governor spring (102), and
a plurality of linkages connecting said governor spring (102) and
said flyweights (104), characterized in that,
said governor spring (102) is a variable pitch spring.
2. The governor (100) as claimed in claim 1, wherein said governor spring (102) is a hook spring (410).
3. The governor (100) as claimed in claim 1, wherein said governor spring (102) is a drawbar spring (420).
4. The governor (100) as claimed in claim 1, wherein said variable pitch spring is a progressive pitch spring.