JP2767609B2 - Vehicle pressure detector mounting device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detector mounting device used for a vehicle equipped with a crankcase preload type two-cycle engine that controls an engine based on a fluctuation amount of a crankcase pressure. Things.

BACKGROUND OF THE INVENTION A fuel injection device that determines the fuel injection amount based on the amount of change in the pressure in the crank chamber, utilizing the fact that the amount of change in the pressure in the crank chamber of a two-stroke engine of a crankcase preload type corresponds to the amount of intake air is known. (JP-A-58-98632, 59-5
875). This engine requires a pressure detector that detects the internal pressure of the crankcase. If this pressure detector is directly attached to the crankcase and directly communicates with the crankcase, the fuel (gasoline) and Lubricating oil, moisture, or the like may flow into the pressure detector, and the pressure receiving portion of the pressure detector may be contaminated or deteriorated, resulting in a change in characteristics, a decrease in performance, or damage.

(Object of the Invention) The present invention has been made in view of such circumstances,
When this engine is installed in a vehicle, the pressure sensor and fuel, lubricating oil, and moisture are prevented from entering, protecting the pressure sensor, stabilizing its characteristics, and preventing performance degradation and damage. An object of the present invention is to provide a pressure detector mounting device for a vehicle.

(Constitution of the Invention) According to the present invention, an object of the present invention is to provide a pressure detector mounting device for use in a vehicle equipped with a crankcase preload type two-cycle engine controlled based on a pressure fluctuation amount of a crankcase pressure. A pressure detector attached to the upper body frame, a pipe extending upward from the crankcase and communicating with the pressure detector, and allowing only outside air to flow into the pipe provided in the middle of the pipe. The invention is achieved by a vehicle pressure detector mounting device, comprising: an air check valve.

(Embodiment) FIG. 1 is a left side view of a motorcycle according to an embodiment of the present invention, FIG. 2 is a conceptual view of a fuel injection device, FIG. 3 is a front view of an engine, and FIG. 5 is a front view of the throttle valve on the right side, FIG. 5 is a sectional view taken along line VV, FIG. 6 is a right side view of the engine, and FIG. 7 is a sectional view of the air check valve.

In FIG. 1, reference numeral 10 denotes a vehicle body frame, 12 denotes a rear arm, 14 denotes a rear wheel, 16 denotes a front fork, 18 denotes a front wheel, 20 denotes a steering handle, 22 denotes a fuel tank, 24 denotes a driving seat, 25 denotes a battery, 26 Is a fairing and 28 is a rear body cover.
Rear arm 12 is cushion unit by link 30, 32
The rear arm 12 is connected to the lower end of the rear arm 34 so that the rear arm 12 has a return behavior downward.

Reference numeral 36 denotes a crankcase preload type two-cycle two-cylinder engine having a front cylinder 38 and a cylinder 40 which form a substantially L-shape in side view. In the crankcase 42, crank chambers 44, 46 (FIG. 2) of the cylinders 38, 40 are independently formed. Reference numeral 48 denotes a crankshaft, and the piston of each cylinder is connected to the crankshaft 48 by a connecting rod.

52 (52a, 52b) are exhaust pipes (FIG. 1).
a extends from the lower surface of the front cylinder 38 to the right side of the rear wheel 14 under the crankcase 42. Also, the exhaust pipe 52b is
Extends from the rear surface through the rear body cover 28 and above the rear wheel 14.

54 is a mechanically driven fuel pump, which has a crankcase
It is driven by the engine via a worm gear mechanism 56 provided on the left side of 42 and a flexible cable 58. That is, the fuel pump 54 is driven by the crankshaft 48 or a shaft which is constantly driven by the crankshaft 48. Since the fuel pump 54 is rotatably driven by the flexible cable 58, the fuel pump 54 is located away from the high-temperature portion of the engine 36 so as to be located at a position where the steering wind can easily hit or at a position where the engine vibration is small. can do. Therefore, it is not adversely affected by heat or vibration of the engine. The pump 54 is formed of, for example, a roller pump, and generates a fuel pressure higher than a required fuel pressure of a fuel injection valve 76 described later.

Reference numeral 60 (60a, 60b) is a shutter type throttle valve.
The two throttle valves 60 are substantially symmetrical and connected to the crankcase 42 by rubber joints 62 (62a, 62b). Note that a reed valve is attached to a connection between the joint 62 and the crankcase 42 (not shown). Throttle body 64 of each throttle valve 60
At (64a, 64b), a valve plate 66 (66a, 66b) is mounted so as to be able to move up and down from above. The rotation of the throttle grip (not shown) provided on the steering handle 20 is transmitted to pulleys 68 (68a, 68b) via wires (FIG. 3),
70 (70a, 70b), valve plate 66 by link 72 (72a, 72b)
To move the valve plate 66 up and down. The opening 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 provided with an electromagnetic fuel injection valve 76 (76a, 76b), which injects fuel obliquely from the vicinity of the lower edge of the valve plate 66 toward the intake flow direction. These fuel injection valves 76 are of a so-called bottom feed type, and are of a type in which fuel is supplied to the injection port side from the electromagnetic coil. Fuel injection valve 76 for both cylinders
The fuel pumped from the fuel pump 54 is distributed and guided to the right and left by a delivery pipe formed by a T-shaped joint pipe 78 and a pipe 79 located therebetween.

Numerals 80 (80a, 80b) denote fuel pressure regulators for controlling the fuel pressure fed from the fuel pump 54 to the injection valve 76 in each of the cylinders 38, 40.
Is adjusted to a predetermined pressure determined by the intake negative pressure. 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 part of the fuel is returned to the fuel tank 22.

This regulator 80 has a diaphragm 82 (82a, 82b)
And the suction negative pressure chamber 84 defined by the diaphragm 82
(84a, 84b) and a heat and pressure chamber 86 (86a, 86b). The fuel pressure chamber 86 is communicated with a pipe connecting the fuel pump 54 and the injection valve 76, and the fuel pressure of the injection valve 76 is guided. A return force to the fuel pressure chamber 86 is applied to the diaphragm 82 by compression springs 88 (88a, 88b). In addition, diaphragm 82
A fuel pressure adjusting nozzle 90 (90a, 90b) faces from inside the fuel pressure chamber 86, and the diaphragm 82 becomes a flapper that approaches and separates from the nozzle 90, thereby forming a known flapper nozzle type pressure adjusting 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 to displace and 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 decreases. Generally, when the load is low, the fuel injection time becomes extremely short, and there is a case where the injection amount cannot be controlled only by the injection time due to the limit of the responsiveness of the fuel injection valve. According to this embodiment, since the injection amount is reduced by lowering the fuel pressure in this case, it is not necessary to increase the responsiveness of the fuel injection valve 76, and high-precision control can be performed without using an expensive fuel injection valve. Becomes possible. Also, when the throttle valve 60 is suddenly closed during high-speed operation, the fuel injection amount also sharply decreases, and the fuel pressure temporarily increases.According to this embodiment, the fuel pressure regulator 80 detects the intake negative pressure As a result, the fuel pressure is quickly released, so that the injection amount can always be accurately controlled. When the diaphragm 82 moves away from the nozzle 90 while compressing the spring 88 in this manner, the fuel in the fuel pressure chamber 86 is returned to the fuel tank 22 from the nozzle 90. The two fuel pressure regulators 80 are both mounted on the outer surface of the throttle body 64 and are close to the fuel injection valve 76, so that the injection pressure can be controlled with high accuracy.

92 (92a, 92b) are pressure detectors for detecting the internal pressure of the crank chambers 44, 46, which are mounted on the frame 10 above the engine 36 via rubber tampers 94 (94a, 94b, FIGS. 1, 6). I have. These pressure detectors 92 are connected to the left and right outer surfaces of the crankcase 42 by pipes 96 (96a, 96b), detect the internal pressure of the crank chambers 44, 46, and generate electric signals p _a , p _b corresponding to the internal pressures. Output. Here, the lower ends of the pipes 96a and 96b are
As shown in FIGS. 1 and 6, each cylinder 38,
It is connected to the cylinder side of 40 and at a position other than the bottom of the crank chambers 44 and 46, so that fuel and the like in the crank chambers 44 and 46 are hard to enter the pipe 96. Preferably, the pipes 96a, 96b are approximately the same length.

The pipe 96 has an air check valve 98 (98a, 9
8b) is installed. As shown in FIG. 7, this check valve 98 allows only outside air to flow into the pipe 96, and guides outside air into the pipe 96 from the check valve 98 when the pressure in the crank chamber becomes negative. By guiding the outside air to the pressure detector 92, the fuel and the like in the crank chambers 44 and 46 are prevented from flowing into the pressure detector 92. 98A is an air filter. 98B is a pressure detector 9 rather than a check valve
A throttle provided in the pipe 96 on the second side. The throttle 98B also prevents fuel or the like from entering the pressure detector 92.

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

Reference numeral 104 (FIG. 1) denotes a control device constituted by a microcomputer, which is accommodated in a space defined by a wall 106 at the rear of the fuel tank 22. This control device 10
4, the throttle opening θ, the crank chamber pressure p _a , p
_b , the rotation speed N, the crank angle α, and the like are input. Further, the control may be performed by inputting various signals such as the engine temperature T, the engine acceleration / deceleration, and the engine brake. The control device 104 determines the optimal fuel injection amount corresponding to the operating state based on these various input signals, obtains the injection time for the injection amount, and opens the fuel injection valve 76. That is, the amount of intake air is determined using the crank chamber pressure and the rotation speed N determined by the pressure detector 92, and the injection time is determined. Here, the control device 104 has a built-in memory, which stores characteristics of the optimum injection amount in advance and determines the injection time. Injection is performed once for each cylinder during one rotation of the crankshaft in synchronization with rotation of the crankshaft based on this injection time.

In this control device 104, various functions of a control circuit such as a CDI ignition control circuit, a control circuit of an electromagnetic lubricating oil pump, an exhaust control valve opening control circuit, and the like are provided in the same unit as necessary. be able to. That is, various control circuit functions can be provided by a control program using one microcomputer.

When the throttle valve opening θ is equal to or less than a certain value and the load is medium to low, the injection time determined by the control device 104 is sufficiently short, and when the engine speed is further increased while maintaining this load, the injection time is further shortened. Therefore, generally, the injection valve 44 cannot respond to the short injection time, and the actual injection amount increases. However, according to this embodiment, in this case, the fuel pressure regulator 80 reduces the fuel pressure to reduce the injection amount. That is, as the throttle valve opening θ decreases, the negative pressure of the intake pipe decreases, and accordingly, the diaphragm 82 compresses the spring 88 and separates from the nozzle 90. Therefore, the fuel in the fuel pressure chamber 86 recirculates from the nozzle 90 to the fuel tank 22, and the fuel pressure applied to the injection valve 76 decreases. As a result, the injection amount decreases.

(Effect of the Invention) As described above, according to the present invention, the pressure detector is mounted on the body frame above the engine, and this is connected to the crank chamber by a pipe. Separated by a pipe. In particular, an air check valve is provided in the middle of this pipe so that outside air flows into this pipe, so that when the pressure in the crankcase rises, this outside air flows into the pressure detector through the pipe. Become. For this reason, fuel, lubricating oil, moisture, and the like in the crank chamber are less likely to flow into the pressure detector. Further, since the air and the fuel in the pipe are cooled by the pipe, the separation of the fuel and the like is performed more favorably. This protects the pressure sensor from fuel, lubricating oil, moisture, etc.,
Its characteristics and performance are stable, and durability is improved.

[Brief description of the drawings]

FIG. 1 is a left side view of a motorcycle according to one embodiment of the present invention, FIG. 2 is a conceptual view of the fuel injection device, FIG. 3 is a front view of the engine, and FIG. 5 is a sectional view taken along line VV of FIG. 5, FIG. 6 is a right side view of the engine, and FIG. 7 is a view showing a structure of an air check valve. 10 ... body frame, 36 ... engine, 42 ... crankcase, 92 ... pressure detector, 96 ... pipe, 98 ... air check valve.

Claims (1)

(57) [Claims] 1. A pressure detector mounting apparatus for use in a vehicle equipped with a crankcase preload type two-cycle engine controlled based on a pressure fluctuation amount of a crankcase pressure, wherein a pressure mounted on a body frame above the engine. A detector, a pipe extending upward from the crankcase and communicating with the pressure detector, and an air check valve provided in the middle of the pipe and allowing only outside air to flow into the pipe. Detector mounting device for a vehicle.