JPH0114741Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a cold start assist device for an internal combustion engine equipped with a fuel injection pump.

In an internal combustion engine equipped with a fuel injection pump, such as a diesel engine, the amount of fuel injected is controlled by a governor connected to a fuel control rod (hereinafter simply referred to as a rack) within a fuel injection pump (hereinafter simply referred to as an injection pump). Among the governors used here, the mechanical governor easily transmits changes in the equilibrium position of the centrifugal force and spring force of the flyweight attached to the tip of the injection pump's camshaft, thereby increasing the effective stroke of the injection pump's plunger. That is, the fuel injection amount is changed so as to decrease as the rotational speed increases.

By the way, in order to match the injection characteristics of the injection pump to the requirements of the engine, diesel engines have
Various efforts have been made. For example, a diesel engine with a supercharger has a low speed and low charge air pressure, but if the supercharger works effectively and increases the amount of air intake into the cylinder, the injection will be appropriate depending on the amount of air in the cylinder. There are some that obtain the amount by the function of a boost compensator. This boost compensator uses the boost pressure increased by the supercharger in the intake pipe to operate the injection pump's rack in the increasing direction, thereby causing the injection pump to inject the appropriate amount of fuel into the cylinder. The aim is to achieve complete combustion of fuel and increase output.

Furthermore, even when starting at a low temperature, the diesel engine
Special equipment is often used. That is, in the case of a direct injection diesel engine, if the cranking speed at low temperature startup is low, the injection amount of the injection pump tends to decrease, and for this reason, an injection amount increasing device at low temperature startup is often installed. For example, some use a solenoid to directly pull the rack in the direction of increasing fuel. However, this has the disadvantage that the device itself becomes large. Furthermore, there is also a push-pull method, but this requires a more complicated mechanism.

The purpose of this invention is to provide a low-temperature starting auxiliary device that is compact and has good tower mountability.

The cold start assist device of this invention is attached to a fuel injection pump that controls the fuel injection amount by moving the rack, and has an air supply chamber that receives the supply pressure of the internal combustion engine equipped with this fuel injection pump, and a A diaphragm that moves the rack in a fuel increasing direction when the internal pressure of the air chamber is higher than a set pressure, a heater installed in the air supply chamber, and a valve that closes the air supply pressure intake of the air supply chamber when the heater is activated. and a heater control circuit connected to the heater, and is configured to drive the heater control circuit when the internal combustion engine is started at a low temperature.

According to such a low-temperature start assist device, the injection amount can be increased by applying a drive current to the heater, thereby performing low-temperature start assist. In this case, the drive current to the heater can be the same as the control system for the intake electric heater, which is often used at the same time, making it easy to control. Furthermore, when this cold start assist device is attached to an injection pump that uses a conventional boost compensator, it can also be used as the boost compensator, requires only a small amount of space, and is easy to mount.

This invention will be explained below with reference to the accompanying drawings.

FIG. 1 shows a diesel engine 2 equipped with a cold start assisting device 1 as an embodiment of this invention. This diesel engine 2 has a governor 3
and an injection pump 5 equipped with a boost compensator 4. This injection pump directly injects fuel into a cylinder (not shown), and the injection amount is controlled by changing the effective plunger stroke of a plunger (not shown) via a rack 6 connected to a governor 3.

The governor 3, as shown in FIG.
A floating lever 10 that transmits changes in the equilibrium position P with the rack 6, and a control lever that transmits the operating force of an accelerator pedal (not shown) to the floating lever (in FIG. )12. In this case, the floating lever 10 receives the elastic force of the joint spring 13 whose lower end faces in the direction of the arrow A, and receives a counterclockwise rotational force around the fulcrum portion 121 of the control lever 12. This rotational force is transmitted to the rack 6 via the upper fork link 14 and the hook piece 15 of the floating lever 10, and this rack is subjected to a pressing force in the fuel increasing direction u. However, here, the hook piece 15 is also used as the boost compensator 4,
Crank 1 that also operates as cold start assist device 1
6, the rack 6 remains in this position, i.e. in the full load rack position R.

A boost compensator 4 and a cold start assist device 1 are provided above the governor 3. That is, the crank 16, which is pivotally connected to the main body of the injection pump 5, has its lower locking end connected to the hook piece 15.
The lateral pivot ends are respectively connected to vertically movable push rods 17, and the upper ends of the push rods are attached to a diaphragm 18. The diaphragm 18 is attached to divide the inner chamber of the cylindrical container 19 into upper and lower parts. That is, the diaphragm 18 is sandwiched between a lower atmospheric chamber 20 that is open to the atmosphere and an air supply chamber 22 that receives the air supply pressure in the air supply pipe 21 via a pipe 25, and the pressing force generated by the pressure difference between the two chambers is exceeds the elastic force of the return spring 23, that is, when the internal pressure of the air supply chamber 22 becomes greater than the set pressure, the push rod 17 can be pressed downward. A supply pressure intake port 24 is formed in the supply air chamber 22, and a valve 26 that can open and close the supply pressure intake port is attached to the supply pressure intake port. Furthermore, a heater 27 is attached to the inner wall of the air supply chamber 22. This heater 27 is connected in parallel with an intake electric heater 28 installed in the air supply pipe 21, which is connected to a heater control circuit 29. The heater switch 30, which connects the heater control circuit 29 to the power source 31 in an intermittent manner, is also connected to a valve switch (not shown) that closes the valve 26, and is configured to close the air supply chamber 22 only when the heater is activated. .

A supercharger 33 is attached to the air supply pipe 21 and exhaust pipe 32 of the diesel engine 2, which utilizes exhaust flow to increase the amount of intake air.

The operation of the low temperature starting assist device 1 shown in FIG. 2 will be explained. When starting the diesel engine 2, first the heater switch 30 is turned on. As a result, the device on the upper part of the governor is
Work as. First, the air supply chamber 22 is closed by the valve 26, and the heater 27 is activated. Then, each member becomes the state shown by the solid line in FIG. 2, and then gradually moves to the state shown in FIG. 3. That is, the air at atmospheric pressure in the air supply chamber 22 is heated by the heater 27, expands thermally, and becomes high in pressure. This causes diaphragm 1
8 presses down the push rod 17 and cranks 1
Reference numeral 6 moves the hook piece 15, that is, the rack 6, in the fuel increasing direction U by a fuel increasing stroke corresponding to the maximum injection amount, and holds it at the fuel increasing position R1 as the rack stop position. At this time, the control lever 12 is in contact with the full load stopper 11,
The floating lever 10 is centered on the fulcrum part 121.
receives the elastic force of the joint spring 13,
Rotate counterclockwise by α angle. At this time, the fly weight 8 side of the governor 3 does not change.

Eventually, the heating of the intake electric heater 28 is also promoted, and then a starter (not shown) is activated,
Start diesel engine 2. Then, the injection pump 5 operates with an injection amount sufficient for starting due to the rack 6 in the fuel increase position R1, the heated air supply also acts effectively, and the diesel engine 2 starts.
After this, a predetermined warm-up is performed and the heater switch 3 is turned on.
0 is turned off.

On the other hand, when the diesel engine 2 is in steady operation, the valve 26 is supported in an open manner, the air supply chamber 22 and the like operate as the boost compensator 4, and the air supply pressure of the air supply pipe 21 is directly applied to this air supply chamber. This boost pressure is relatively large during medium and high speed rotation when the supercharger 33 is effectively operating. When receiving this supercharging pressure, the diaphragm 18 pushes the push rod 17 downward, the crank 16 rotates, and the rack 6 is allowed to move in the fuel increasing direction u. And Rack 6 is maximum, 3rd
It moves to the fuel increase position R1 shown in the figure, and operates the injection pump 5 with an injection amount corresponding to this position. Incidentally, the rotation of the camshaft 7 of the injection pump 5 also operates the flight weight 8 side of the governor. Therefore, when the maximum rotational speed is exceeded, the fly weights 8 are activated, regardless of whether the operating range is low load or high load, and even when the rack 6 is in the fuel increase position R1.
The equilibrium position P is biased to the left. As a result, the floating lever 10 rotates clockwise around the fulcrum portion 121 to fully pull the rack 6 in the fuel depletion direction -u, thereby preventing the diesel engine 2 from overrunning.

The low-temperature starting assist device 1 shown in FIG. 2 can move the rack 6 to the fuel increase position R1 during low-temperature starting, and can supply an appropriate amount of fuel to the injection pump 5 even during cranking, improving startability. .
Moreover, the boost compensator 4 can be effectively used as the low temperature start assist device 1, and the new additions as the low temperature start assist device 1 are the heater 27 and the valve 2.
6, requires little installation space and is easy to mount.

FIG. 4 shows a cold start assisting device 34 as another embodiment of this invention. Since this low temperature starting aid device includes the same components as those shown in Figure 2,
Hereinafter, the same members will be denoted by the same reference numerals, and the description thereof will be omitted. This low temperature starting auxiliary device 34 is the injection pump 5
On the other hand, a governor 3 and a boost compensator 35 installed on the opposite side of the governor are installed. This boost compensator 35 is also used as the cold start assist device 34. That is,
The diaphragm 38 is sandwiched between the left and right sides of the air supply chamber 36 and the atmospheric chamber 37 which receive the supply pressure of the air supply pipe 21, and the lower end of the arm 40 is rotated via the push rod 39 due to the pressure difference between the two chambers. This arm 40 is pivotally mounted on the base plate side of the injection pump 5, and its upper end abuts against the front end of the rack 6. The rear end of the rack 6 is connected via a fork link 14 to a governor 3 similar to that shown in FIG. A heater 27 and a valve 26 are also installed in the air supply chamber 36, and the heater has a first
A heater control circuit 29, a heater switch 30, and a power source 31 similar to those shown in the figure are connected in this order.

The low temperature starting auxiliary device 34 includes a heater 27 and a valve 26.
As a result of this operation, the internal pressure of the air supply chamber 36 is increased, and the diaphragm 38 rotates the arm 40 counterclockwise via the push rod 39. At this time arm 4
0, the movement in the fuel increasing direction u is stopped,
The rack 6 in the full load rack position R comes into contact with the other side of the arm 40, which has one side in contact with the stopper bolt 41, and is held in the fuel increase position R1.
This allows the injection pump 5 to operate with an injection amount suitable for low-temperature startup. On the other hand, diesel engine 2
During steady operation, the boost compensator 35 operates. In this case, the supply pressure increased by the supercharger 33, which operates effectively at medium and high speeds, is applied to the supply air chamber 36.
In addition, the diaphragm 38 rotates the arm 40 to move the rack 6 to the maximum fuel increase position R1, thereby obtaining a proper injection amount.

This low temperature starting assist device 34 also exhibits the same effect as the low temperature starting assist device 1 shown in FIG. In particular, using the stopper bolt 41, it is easy to adjust the fuel increase position R1.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a diesel engine equipped with a low-temperature starting assist device as an embodiment of the invention, FIGS. 2 and 3 are sectional views of essential parts of the same low-temperature starting assist device in different states, and FIG. The figures each show a sectional view of a main part of a cold start assisting device as another embodiment of this invention. 1, 34...Cold start auxiliary device, 2...Diesel engine, 5...Injection pump, 6...Rack, 18,38...Diaphragm, 22,36...
... air supply chamber, 24 ... supply pressure intake, 26 ... valve,
27... Heater, 29... Heater drive circuit, R1
...Fuel position increase.

Claims (1)

[Scope of utility model registration request] An air supply chamber that is attached to a fuel injection pump that controls the amount of fuel injected by easy movement and receives the supply pressure of the internal combustion engine equipped with this fuel injection pump, and an internal pressure of this air supply chamber that is higher than the set pressure. a diaphragm that moves the rack in a fuel increasing direction when the rack is in use; and a heater installed in the air supply chamber;
It has a valve that closes the air supply pressure intake of the air supply chamber when the heater is activated, and a heater control circuit connected to the heater, and is configured to drive the heater control circuit when the internal combustion engine is started at a low temperature. A low temperature starting aid device characterized by: