JPH02298632A - Pressure detector attaching device for vehicle - Google Patents

Abstract

PURPOSE:To protect pressure detectors from fuel, lubricating oil and water by providing pressure detectors to a vehicle body frame above an engine, and communicating the same to a crank case via pipes, in an article for deciding fuel injection quantity based on variation quantity of internal pressure of the crank case. CONSTITUTION:Crank chambers of respective cylinders 38, 40 are independently formed in a crank case 42, in a crank chamber pre-pressurizing type two cycle two cylinder engine 26 having a front cylinder 36 and an upper cylinder 40 and equipped on a motor cycle. Utilizing that internal pressure of the crank chamber corresponds to the intaken air quantity, respective crank chamber internal pressures are detected with pressure detectors 92 (92a, 92b), and fuel injection quantity is decided based on these pressure variation quantities. In this case, respective pressure detectors 92 are mounted via rubber dampers 94a, 94b of a frame 10 above the engines 36. Respective pressure detectors 92 are communicated and connected to right and left outer side face of the crank case 42 with pipes 96a, 96b, and made to generate electric signals corresponding to crank chamber internal pressures.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle equipped with a crank chamber preload type two-stroke engine that determines the amount of fuel injection based on the amount of variation in crank chamber pressure.

(Background of the Invention) There is a known fuel injection device that takes advantage of the fact that the amount of fluctuation in the crank chamber pressure of a two-stroke engine with preloaded crank chamber corresponds to the amount of intake air, and determines the amount of fuel to be injected based on the amount of fluctuation in the crank chamber pressure. This engine requires a pressure detector to detect the internal pressure of the crank chamber.
If this pressure detector is directly attached to the crankcase and communicated with the crank chamber, fuel (gasoline), lubricating oil, moisture, etc. in the crank chamber will flow into the pressure detector, causing the pressure receiving part of the pressure detector to It may become contaminated or deteriorated, resulting in changes in properties, reduced performance, or damage.

(Purpose of the Invention) The present invention has been made in view of the above circumstances, and is designed to prevent fuel, lubricating oil, and moisture from entering the pressure detector when this engine is installed in a vehicle. The purpose of the present invention is to provide a pressure sensor mounting device for a vehicle that protects the pressure sensor, stabilizes its characteristics, and prevents performance deterioration and damage.

(Structure of the Invention) According to the present invention, this purpose is to detect the crank chamber pressure,
In a vehicle equipped with a crank chamber pre-pressure type two-stroke engine that determines the fuel injection amount based on the amount of pressure fluctuation, a pressure sensor is installed on the body frame above the engine, and a pressure sensor that extends upward from the crank chamber is installed on the vehicle body frame above the engine. This is achieved by a pressure sensor mounting device for a vehicle, which is characterized by comprising a vibrator communicating with the pressure sensor.

(Example) Fig. 1 is a left side view of a motorcycle which is an embodiment of the present invention, Fig. 2 is a conceptual diagram of its fuel injection device, Fig. 3 is a front view of the engine, and Fig. 4 is a traveling direction. 6 is a front view of the throttle valve on the right side as viewed from the front, FIG. 5 is a sectional view taken along the line V-V, FIG. 6 is a right side view of the engine, and FIG. 7 is a sectional view of the air check valve. , code 10 is the vehicle body frame, 1
2 is the rear arm, 14 is the rear wheel, 16 is the front fork, 18
is the front wheel, 20 is the steering wheel, 22 is the fuel tank, 24
is the driver's seat, 25 is the battery, 26 is the fairing, 28
It is a full body cover. Rear arm 12 is link 3
0.32 to the lower end of the cushion unit 34, giving the rear arm 12 a downward return habit.

Reference numeral 36 is a two-stroke, two-cylinder engine with preloaded crank chamber, consisting of a front cylinder 38 and an upper cylinder 40 that form a curved shape when viewed from the side.
and has. Each cylinder has 38.40 mm in the crankcase 42.
Crank chambers 44 and 46 (Fig. 2) are formed independently. 48 is a crankshaft, and the pistons of each cylinder are connected to this crankshaft 48 by connecting rods.

52 (52a, 52b) are exhaust pipes (Fig. 1),
The exhaust pipe 52a extends from the lower surface of the front cylinder 38 to the crankcase 4.
2 and extends to the right side of the rear wheel 14. In addition, the exhaust pipe 52b is connected to the rear surface of the upper cylinder 40 by the body cover 28.
It passes through the inside and extends above the rear wheel 14.

A mechanically driven fuel pump 54 is driven by the engine via an ohmic gear mechanism 56 provided on the left side of the crankcase 42 and a flexible cable 58. That is, this fuel pump 54 is driven by the crankshaft 48 and a shaft that is constantly driven by the crankshaft 48. Since the fuel pump 54 is rotationally driven by a flexible cable 58, it is possible to place the fuel pump 54 away from the high temperature part of the engine 36 and in a position where it is easily exposed to steering wind.
It can be placed in a position with less engine vibration. Therefore, it is not adversely affected by engine heat or vibration.

This pump 54 is constituted by, for example, a roller pump, and generates a fuel pressure higher than the required fuel pressure of a fuel injection valve 76, which will be described later.

60 (60a, 60b) are shutter type throttle valves. Both throttle valves 60 are made almost symmetrically,
Each is connected to the crankcase 42 by a rubber joint 62 (62a, 62b). A reed valve (not shown) is installed at the connection between the joint 62 and the crankcase 42. A valve plate 66 (66a, 66b) is attached to the throttle body 64 (64a, 64b) of each throttle valve 60 from above so as to be movable up and down. The rotation of the throttle grip (not shown) provided on the steering handle 20 is transmitted to the pulleys 68 (68a, 68b) via wires (Fig. 3), and further to the levers 70 (70a, 70b) and the links. 72 (7
2a, 72b) to the valve plate 66.
to raise and lower. The opening degree θ of the throttle valve 60 is detected by a potentiometer 74 attached to the right side of the right throttle valve 60b.

Each of the throttle bodies 64 is equipped with an electromagnetic fuel injection valve 76 (76a, 76b), which injects fuel obliquely toward the intake flow direction from near the lower edge of the valve plate 66. These fuel injection valves 76 are of a so-called bottom-feed type, and are of a type in which fuel is supplied from the side closer to the injection port than the electromagnetic coil. The fuel pumped from the fuel pump 54 is distributed to the left and right sides of the solid-cylinder fuel injection valve 76 by a delivery vibe formed by a T-shaped joint pipe 78 and a vibe 79 located between the two.

80 (80a, 80b) is a fuel pressure regulator, which adjusts the fuel pressure fed from the fuel pump 54 to the injection valve 76 to a predetermined pressure determined by the intake negative pressure of each cylinder 38, 40. That is, when the fuel pressure supplied from the fuel pump 54 to the injection valve 76 exceeds a predetermined pressure determined by the intake negative pressure, a portion of the fuel is circulated back to the fuel tank 22.

This regulator 80 includes a diaphragm 82 (82a,
82b), an intake negative pressure chamber 84 (84a, 84b) and a fuel pressure chamber 86 defined by this diaphragm 82.
(86a, 86b). The fuel pressure chamber 86 is communicated with a vibrator connecting the fuel pump 54 and the injection valve 76, and the fuel pressure of the injection valve 76 is introduced thereto. A return force toward the fuel pressure chamber 86 is applied to the diaphragm 82 by a compression spring 88 (88a, 88b). The diaphragm 82 also has a fuel pressure adjustment nozzle 90 (90a
, 90b) are opposed to each other, and the diaphragm 82 is connected to this nozzle 9.
The flapper approaches and moves away from zero, forming a known flapper-nozzle pressure adjustment mechanism.

Therefore, when the fuel pressure increases beyond a predetermined level, the pressure in the fuel pressure chamber 86 increases, and the diaphragm 82 compresses the spring 88 and is displaced to open the nozzle 90. Since the intake negative pressure is guided to the negative pressure chamber 84, when the intake negative pressure increases, the fuel pressure at which the nozzle 90 starts to open becomes lower. Generally, when the load is low, the fuel injection time becomes extremely short, and there are cases where the injection amount cannot be controlled solely by the injection time due to the limit of the responsiveness of the fuel injection valve 76. According to this embodiment, in this case, the injection amount is reduced by lowering the fuel pressure, so the fuel injection valve 76
There is no need to increase the responsiveness of fuel injection valves, and highly accurate control becomes possible without using expensive fuel injection valves. Furthermore, if the throttle valve 60 is suddenly closed during high-speed operation, the fuel injection amount will also suddenly decrease and the fuel pressure will temporarily increase, but according to this embodiment, the fuel pressure regulator 80 detects the intake negative pressure. Since the fuel pressure is quickly released, accurate control of the injection amount is possible at all times. When the diaphragm 82 leaves the nozzle 90 while compressing the spring 88 in this manner, the fuel in the fuel pressure chamber 86 is returned from the nozzle 90 to the fuel tank 22. Note that the two fuel pressure regulators 80 are both attached to the outer surface of the throttle body 64, and the fuel injection valves 76
Since the injection pressure is close to , highly accurate control of the injection pressure is possible.

92 (92a, 92b) are pressure detectors for detecting the internal pressure of the crank chamber 44.46, and a rubber tamper 94 (94a, 94b, first
．． (Fig. 6). These pressure detectors 92 are provided with vibrators 96 on the left and right outer surfaces of the crankcase 42.
(96a, 96b), and the crank chamber 44.4
detects the internal pressure of 6, and generates an electric signal p1 corresponding to this internal pressure,
Output pb. As shown in FIG. 1.6, the lower ends of the vibrators 96a, 96b are located closer to the cylinders 38, 40 than the crankshaft 48, and are located closer to the crank chamber 44.
46 in a position other than the bottom of the crank chamber 44.4.
The fuel inside the vibrator 6 is made difficult to enter the vibrator 96. It is preferable that the vibrators 96a and 96b have approximately the same length.

In addition, each vibrator 96 has an air check valve 98 (9
8a, 98b) are attached. This check valve 9
8, as shown in FIG. 7, allows only outside air to flow into the vibrator 96. When the crank chamber becomes negative pressure, the check valve 98 guides the outside air into the vibrator 96, and this outside air is By guiding the fuel into the pressure detector 92, fuel and the like in the crank chambers 44, 46 are prevented from flowing into the pressure detector 92. Note that 98A is an air filter. 98
B is the vibrator 9 closer to the pressure detector 92 than the check valve 98
6, and this throttle 98B also prevents fuel etc. from entering the pressure detector 92.

A rotation speed detector 100 (FIG. 2) detects the rotation speed N and crank angle α of the crankshaft 48, and is housed in a magneto 102 (FIG. 3) on the left side of the crankcase 42.

104 (FIG. 1) is a control device composed of a microcomputer, and a wall 106 is installed at the rear of the fuel tank 22.
It is housed in a space defined by. Signals such as the throttle opening θ, the crank chamber pressure p-5Pb, the rotational speed N, and the crank angle a are input to the control device 104. Further, various signals such as engine temperature T, engine acceleration/deceleration, engine brake, etc. may be input for control.The control device 104 determines the optimal fuel injection amount corresponding to the operating condition based on these various input signals. , the injection time for this injection amount is determined and the fuel injection valve 76 is opened. That is, the intake air amount is determined using the crank chamber pressure and rotational speed N determined by the pressure detector 92, and the injection time is determined. The control device 104 has a built-in memory in which characteristics of the optimum injection amount are stored in advance, and the injection time is determined. Based on this injection time, one injection is applied to each cylinder during one rotation of the crankshaft in synchronization with the rotation of the crankshaft.
Perform multiple injections.

The control device 104 is designed to have the functions of various control circuits in the same unit as necessary, such as a CDI ignition control circuit, an electromagnetic lubricating oil pump control circuit, and an exhaust control valve opening control circuit. be able to. i.e. 1
Various control circuit functions can be provided using a single microcomputer and a control program.

The injection time determined by the control device 104 is sufficiently short when the throttle valve opening θ is below a certain level and the engine speed increases, and the injection time becomes even shorter when the engine speed increases while the load remains the same. Therefore, the injection valve 44 generally cannot respond to this short injection time, and the actual injection amount increases. However, according to this embodiment, in this case, the fuel pressure regulator 80 lowers the fuel pressure and reduces the injection amount. That is, as the throttle valve opening θ decreases, the intake pipe negative pressure decreases, and the diaphragm 82 compresses the spring 88 and moves away from the nozzle 90. Therefore, the fuel in the fuel pressure chamber 86 flows back to the fuel cylinder 22 from this nozzle 90, and the fuel pressure applied to the injection valve 76 decreases. As a result, the injection amount will decrease.

(Effects of the Invention) As described above, the present invention has a pressure detector attached to the vehicle body frame above the engine, which is communicated with the crank chamber through a pipe, so that fuel, lubricating oil, moisture, etc. separated by a pipe. In particular, since the air and fuel inside the pipe are cooled by this pipe, separation of fuel and the like is performed even better. This protects the pressure sensor from fuel, lubricating oil, moisture, etc., stabilizes its characteristics and performance, and improves its durability.

[Brief explanation of the drawing]

Fig. 1 is a left side view of a two-axle automatic vehicle that is an embodiment of the present invention, Fig. 2 is a conceptual diagram of its fuel injection system, Fig. 3 is a front view of the engine, and Fig. 4 is a view facing the direction of travel. 5 is a front view of the right throttle valve, FIG. 5 is a sectional view taken along the line V-V), FIG. 6 is a right side view of the engine, and FIG. 7 is a diagram showing the structure of the air check valve. lO...Vehicle frame, 36...Engine, 42.
...Crankcase, 92...Pressure detector, 96...Pipe.

Claims (1)

[Claims] In a vehicle equipped with a crank chamber preload type two-stroke engine that detects the crank chamber pressure and determines the fuel injection amount based on the amount of pressure fluctuation, a pressure detector attached to the body frame above the engine and a crank chamber A pressure detector mounting device for a vehicle, comprising: a pipe extending upward from the chamber and communicating with the pressure detector.