Claims:We Claim:

1. A device (100) for controlling the speed of a fuel injection pump in a vehicle:
said device (100) located in-between an accelerator cable (102) and a governor lever (104) of said fuel injection pump, said device comprising at least:
a housing (101) with a rail (103);
a plate (108) mounted on said housing, said plate adapted to move along said rail (103);
a first spring (110) and a second spring (112);
said first spring (110) engaged to said plate (108) and said accelerator cable 102, and said second spring (112) engaged to said plate 108 and said governor lever 104; and
a stopping means (114) mounted on said plate (108), said stopping means adapted restrict the movement of said plate 108 along said rail (103).

2. The device 100 of claim 1, wherein said stopping means 114 is at least one of a plate 108 with serrations, magnet, gear mechanism, and brake pad.

3. The device 100 of claim 1 and 2, wherein said stopping means 114 is actuated through a first solenoid 116, said first solenoid 116 receiving input from an electronic control unit.

4. The device 100 of claim 1 and 4, further comprising a second solenoid for receiving input from an air-conditioner of said vehicle.

5. The device 100 of claim 1, wherein said rail 103 comprises at least one of a roller, a worm and worm wheel, a gear mechanism, and a sliding contact.

6. An electronic control unit for a device 100, said device 100 adapted to control the speed of a fuel injection pump in a vehicle, said electronic control unit comprising:

an input interface adapted to receive the actual speed of a vehicle from a speed sensor;

a processing unit adapted to interact with said input interface and compare said actual speed with respect to a set speed for said vehicle; and

an output interface adapted to interact with said processing unit and actuating a stopping means 114 for restricting the movement of a plate 108 along a rail 103 when actual speed is greater than set speed.

, Description:Field of the invention

[0001] This invention relates to the field of speed control for a fuel injection pump in a vehicle and in general a mechanical fuel injection pump.

Background of the invention

[0002] For a mechanical fuel injection pump, the speed of the pump is controlled by a governor. The governor receives input from an accelerator lever and accordingly controls the amount of fuel that the needs to be pressurized in the fuel injection pump. For the present day, speed regulation requirements by government and regulatory authorities, there is a need to bring about a simple speed control mechanism. Known, in the current state of art is the use of electronic speed limiters. However these kind of limiters are expensive and require the use of complex logic. For emerging markets, and for vehicles using conventional mechanical fuel injection pumps, there is need to bring about speed governing in accordance with the regulation requirements in a cost effective way.

[0003] Prior art patent application SU-1726813 discloses a control device consists of a spring loaded accelerator pedal connected to a manual control lever and to the fuel pump speed regulator lever by a rod, with both the pedal and manual control lever linked kinematically to the other end of the rod. The drive is equipped with a handle for selecting and locking the operating mode, a two-arm lever on a spring loaded support, and a flexible element. One arm of the two-arm lever is connected to the rod, and the other to the selector handle, while the flexible element is in the form of a compression spring between the support and the fuel pump rack. A second support is connected to the central pivot of a two-arm lever which controls the fuel feed correction. The right-hand arm of the lever is connected via a pivot to the operating mode corrector housing, and by its other arm to the control handle cable.

Brief description of the accompanying drawing

[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0005] FIG. 1 illustrates a device for controlling the speed of a fuel injection pump;

[0006] FIG. 2a illustrates a stopping means of the device that is used for controlling speed of the fuel injection pump under free condition; and

[0007] FIG. 2b illustrates a stopping means of the device that is used for controlling speed of the fuel injection pump under locked condition.

Detailed description of the embodiments

[0008] FIG. 1 illustrates a device 100 for controlling the speed of a fuel injection pump. The device 100 is located in-between an accelerator cable 102 and a governor lever 104 of the fuel injection pump. The device comprises at least a housing with a rail 103, a plate 108 mounted on the housing and adapted to move along the rail 103, and a first spring 110 and a second spring 112. The first spring 110 is engaged to the plate 108 and the accelerator cable 102, and, the second spring 112 engaged to the plate 108 and the governor lever. The rail 103 comprises at least one of a roller, a worm and worm wheel, and a gear mechanism. This is required for enabling movement of the plate 108 along the rail 103. A stopping means is mounted on the plate 108 and adapted restrict the movement of the plate 108 along the rail 103. The stopping means is at least one of a plate 108 with serrations, magnet, gear mechanism, and brake pad. The stopping means is actuated through a first solenoid 116, the first solenoid 116 receives input from an electronic control unit. In an embodiment the device 100 may also comprise a second solenoid 118 for receiving input from an air-conditioner.

[0009] The constructional features of the device 100 for controlling speed of the fuel injection pump will now be described in further detail. The device 100 comprises a housing with a rail 103. A plate 108 is mounted on the housing in such a way that movement of plate 108 is possible along the rail 103, with the help of a roller, gear mechanism, a sliding contact between, worm and worm wheel, and a sliding contact. A first spring 110 and a second spring 112 are engaged to the plate 108. The first spring 110 is also engaged to the accelerator lever, and the second spring 112 is engaged to the governor lever 104. A stopping means 114 is mounted on the plate 108. A first solenoid 116 is attached to the stopping means 114.

[00010] FIG. 2a illustrates a stopping means of the device 100 that is used for controlling speed of the fuel injection pump under free condition. The stopping means 114 disclosed herein may be at least one of a plate 108 with serrations, magnet, gear mechanism, and brake pad. For the purpose of better understanding the stopping means 114 in FIG.2a can be considered as a plate with serrations. When the speed of the vehicle is less than or equal to the set speed the first solenoid 116 is under de-actuated condition and there is no resistance offered by the stopping means 114 (plate with serrations) with respect to the plate 108 that is mounted on the rail as there is no contact established between the first solenoid 116 and the stopping means 114.

[00011] FIG. 2b illustrates a stopping means 114 of the device that is used for controlling speed of the fuel injection pump under locked condition. When the first solenoid 116 is actuated, the stopping means 114 (plate with serrations) offers resistance to the movement of the plate 108 along the rail 103. The solenoid may cause a plate 108 to engage with the stopping means 114. The plate 108 can no longer move along the rail 103, as the stopping means 114 now offers resistance to the movement of the plate 108.

[00012] An electronic control unit (ECU) is used to control the device that is adapted to control the speed of the fuel injection pump in the vehicle. The ECU comprises an input interface adapted to receive the actual speed of a vehicle from a speed sensor. A processing unit is adapted to interact with the input interface and compare the actual speed with respect to a set speed for the vehicle. An output interface is adapted to interact with the processing unit and actuate a stopping means 114 for restricting the movement of the plate 108 along the rail 103 when actual speed is greater than set speed.

[00013] The working of the device 100 for controlling the speed of the fuel injection pump will be explained in further detail, when a vehicle incorporating above mentioned device 100 is being driven by a user under the following two conditions. Condition 1: When the current speed of the vehicle is less than set speed or the maximum permissible speed. The accelerator cable 102 provides a linkage for increasing the speed of the vehicle. As the accelerator lever is pressed, the first spring 110 that is connected to the accelerator lever pulls the plate 108 in a first direction. The movement of the plate 108 results in the second spring 112 pulling the governor lever 104. The plate 108 moves along the length of the rail 103. The governor lever 104 in turn rotates the control rod through rack and pinion mechanism resulting in more amount of fuel to be drawn into the fuel injection pump to match the demand for speed. This continues as long as the set speed is less than or equal to the permissible speed limit. When the set speed exceeds the permissible speed, then the actual speed has to be reduced in order to meet the regulatory requirements. This is achieved in condition 2 as described below.

[00014] Condition 2: When the vehicle exceeds the set speed, then the electronic control unit that receives the actual vehicle speed as an input, compares the actual speed with respect to the set speed of the vehicle, and energizes the solenoid for locking movement of the plate 108 along the slot when actual speed is greater than set speed. The restriction in movement of plate 108 happens through the stopping means 114 that is mounted on the plate 108. The stopping means 114 grips the plate 108, thereby preventing the plate 108 from moving any further. The first spring 110 that is connected to the accelerator lever expands, to compensate for the additional pressing of the accelerator lever. Since the plate 108 is locked, the second spring 112 second spring 112 also expands, causing the governor lever 104 to maintain a constant position with respect to the control rod. Since the control rod does not rotate further, the amount of fuel coming into the fuel injection pump is reduced. Hence the speed of the pump and in turn the power produced by the engine is reduced.

[00015] In addition to the above mentioned condition, there may a case, the vehicle may be running with air-conditioner ON. In such a case, a second solenoid 118 may be located on the plate 108, the second solenoid 118 takes input from air-conditioner or any other device 100 that causes reduction in speed, when in use. The actuation of second solenoid 118 results in movement of the plate 108 in the direction in which the accelerator cable 102 is pressed, so as to increase the speed of the pump to compensate for the load due to air conditioner.

[00016] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of the stopping means adapted to restrict the movement of plate. 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.