JPH04362209A - Lubrication device of air-fuel injection type two cycle engine - Google Patents

Abstract

PURPOSE:To reduce the consumption of lubricating oil, suppress white smokes of the exhaust gas and prevent the carbon from being built up on a sealing surface or the like of an injection valve. CONSTITUTION:In an air-fuel injection type two cycle engine where fuel together with compressed air is directly injected into cylinders, a constitution is made by internal surfaces of cylinder bores 2a-2c, engine lubricating parts of crank shaft bearing parts 6b-6d, and a lubricating device 7 to supply lubricating oil with an air pump 10 where compressed air is generated. There are provided an engine lubrication system 8 to supply lubricating oil with the engine lubricating parts and a pump lubrication system 9 to supply lubricating oil with the air pump 10 in a separate manner. Setting is made so that the discharge quantity of the lubricating oil per unit time by the pump lubrication system 9 may be smaller than the discharge quantity of the lubricating oil per unit time by the engine lubrication system 8.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubrication system for an air-fuel injection type two-stroke engine, and more particularly to an improvement in the lubricating oil discharge amount set value so that the amount of lubricating oil to the air pump can be adjusted appropriately.

0002

2. Description of the Related Art Recently, an air-fuel injection type two-stroke engine in which fuel is directly injected into a cylinder together with compressed air has been attracting attention as an engine that can eliminate the structural defects of a two-stroke engine. This type of engine is generally equipped with an air pump that generates the compressed air to assist in injecting fuel into the cylinders. Conventionally, such air pumps have generally been of the piston type, in which a piston inserted into a cylinder is reciprocated by the rotation of a crankshaft. It is necessary to lubricate the crankshaft bearing. Conventionally, as a lubricating device for such an air pump, an electromagnetic pump of the same type as an electromagnetic pump for supplying lubricating oil to engine lubricating parts such as the inner surface of the engine's cylinder bore and the crankshaft bearing is used for lubricating the air pump. It is common to add an additional air pump, or to add an air pump lubrication outlet to the engine lubrication distribution pump.

0003

However, in the conventional apparatus in which the electromagnetic pump is added, the electromagnetic pump for the air pump is also driven with the same drive pulse as the electromagnetic pump for engine lubrication. Furthermore, in a conventional device in which an air pump lubrication outlet is added to a distribution pump, the air pump lubrication outlet is also set to have the same diameter as the engine lubrication outlet. Therefore, in conventional lubrication systems, the amount of lubricating oil supplied to the air pump and the amount of lubricating oil supplied to the engine are approximately equal, and as a result, more lubricating oil than necessary is often supplied to the air pump. However, there is a problem that the amount of lubricating oil consumed increases, and there is also a problem that the lubricating oil is likely to be mixed into the compressed air. If the amount of lubricating oil mixed into the compressed air increases, white smoke will increase in the exhaust gas, worsening the exhaust gas condition, or the lubricating oil will be injected mixed with the moisture contained in the compressed air. This causes problems such as carbon deposits on the sealing surfaces of injection valves, spark plugs, etc.

The present invention has been made in view of the above-mentioned conventional problems, and by optimizing the amount of lubricating oil to the air pump, it is possible to reduce the amount of lubricating oil consumed, and also to prevent the lubricating oil from being mixed into the compressed air. An object of the present invention is to provide a lubricating device for an air-fuel injection type two-stroke engine that can suppress white smoke from exhaust gas and prevent carbon deposition on the sealing surface of an injection valve.

[0005]

[Means for Solving the Problems] The present invention provides an air-fuel injection type two-stroke engine in which fuel is directly injected into the cylinder together with compressed air.
A lubrication device that supplies lubricating oil to engine lubricating parts such as a crankshaft bearing part and the air pump that generates the compressed air, the lubricating system providing lubricating oil to the engine lubricating part and the air pump. A pump lubrication system for supplying oil is provided separately, and the amount of lubricant discharged per unit time by the pump lubrication system is set to be smaller than the amount of lubricant discharged per unit time by the engine lubrication system. In the present invention, the pump lubrication system and the engine lubrication system are provided separately and independently, for example, by adding an electromagnetic pump for the air pump, or by adding an air pump discharge port to the distribution pump. can. In addition, in order to make the lubricating oil discharge amount for the air pump smaller than the lubricating oil discharge amount for the engine, for example, if an electromagnetic pump for the air pump is added, the number of drive pulses to the electromagnetic pump for the pump should be changed to the electromagnetic pump for the engine. It is sufficient to reduce the number of driving pulses. In addition, if an air pump discharge port is added to a distribution pump, the discharge port diameter and pump chamber capacity should be set so that the discharge volume from this discharge port is smaller than the discharge volume from other discharge ports. . Furthermore, if the pump lubricating oil discharge amount is set to be smaller than the engine lubricating oil discharge amount, the pump lubricating oil discharge amount will be the engine lubricating oil discharge amount multiplied by a certain ratio regardless of the engine operating condition. It is possible to adopt a method in which the above-mentioned ratio is changed according to the amount or the operating state of the engine. Further, the above ratio is appropriately set according to the number of cylinders of the engine, characteristics of the engine, usage, etc., so that the minimum amount of lubricating oil necessary for lubrication of the air pump can be obtained.

[0006]

[Operation] According to the lubricating device according to the present invention, the amount of lubricating oil discharged from the pump is set to be smaller than the amount of lubricating oil discharged from the engine, so that the amount of lubricating oil consumed can be reduced accordingly. In addition, since the amount of air mixed into the compressed air can be suppressed, white smoke in the exhaust gas can be suppressed, making the exhaust gas cleaner.
Prevents carbon buildup around injection valves, spark plugs, etc.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. 1 and 2 are diagrams for explaining a lubrication system for an air-fuel injection type two-stroke engine according to an embodiment of the present invention, with FIG. 1 being a system diagram thereof and FIG. 2 being a flowchart diagram thereof. This embodiment is an example in which a distribution type pump is used for engine lubrication and an electromagnetic pump is used for air pump lubrication.

In the figure, reference numeral 1 denotes an air-fuel injection type two-stroke engine, in which pistons 3a to 3c are slidably inserted into three cylinder bores 2a to 2c formed in parallel in a cylinder block 2. Each piston 3a-3
c is connected to crank arms 5a to 5c of the crankshaft 5 by connecting rods 4a to 4c. Moreover, this crankshaft 5 has both ends thereof and each crank arm 5a to 5.
The portion between the crank arms 5a and 5c is pivotally supported by the first to fourth journal bearings 6a to 6d, and the crank arms 5a to 5c are located within the crank chambers 2d to 2f. Although not shown, the cylinder head mounted on the upper surface of the cylinder block 2 is equipped with an air-fuel injection device that directly injects and supplies fuel together with compressed air to each of the cylinder bores 2a to 2c.

Reference numeral 7 denotes a lubricating device, which is mainly composed of an engine lubrication system 8 that lubricates the necessary lubrication points of the engine 1 and a pump lubrication system 9 that lubricates the necessary lubrication points of the air pump 10. The engine lubrication system 8 is
It has the following configuration. A branch passage of a suction passage 14 connected to an oil tank 13 is connected to a suction port 12a of a distribution oil pump 12 driven by a step motor 11. Three of the six discharge ports 12b of the oil pump 12 are connected to the cylinder bores 2a to 2c via cylinder discharge passages 15a to 15c, and the remaining three are connected to the crankshaft discharge passages 16a to 15c. It is connected to the second to fourth journal bearings 6b to 6d via 16c. Further, the crank chambers 2d to 2f are connected to the oil tank 13 via a return passage 17. Reference numeral 18 designates a one-way valve for preventing backflow provided in the vicinity of the crank chamber of the return passage 17, and reference numeral 19 designates a filter for filtering the oil returned to the oil tank 13. Note that 20 is an alternator with an integrated vacuum pump, and lubricating oil is supplied to the bearing portion of this alternator by an electric pump 21.

The pump lubrication system 9 connects the suction passage 14 to the suction port 22a of the electromagnetic pump 22.
The discharge port 22b is connected to the crank chamber 23a of the air pump 10 through a discharge passage 24a, and the crank chamber 23a is connected to the return passage 17 through a return passage 24b. Note that 25a and 25b are one-way valves, and these are for returning the lubricating oil accumulated in the crank chamber 23a to the oil tank 11 when the pressure inside the crank chamber 23a becomes positive. The air pump 10 is
A piston 26 is installed in the cylinder bore 23b of the casing 23.
is slidably inserted and connected to a crankshaft 28 with a connecting rod 27, and this crankshaft 28 is driven by the engine 1 via a pulley 29.
3c is connected to the above-mentioned air fuel injection device.

The step motor 11 that drives the oil pump 12 and the electromagnetic pump 22 are controlled by an on-vehicle control unit (not shown). This control unit has a built-in three-dimensional map for calculating the required fuel using engine speed and intake air amount as parameters, and calculates the amount of fuel required per unit time from this map, and calculates the amount of fuel required per unit time. Multiply by a predetermined ratio to determine the amount of engine lubricant oil required to be discharged per unit time. Pump 1 for obtaining the above-mentioned engine lubricating oil discharge amount
The number of times the engine is cranked per discharge is determined, and this interval signal is supplied to the step motor 11. On the other hand, regarding the drive of the electromagnetic pump 22, the pump 2
The drive pulse signal is set so that the discharge amount per unit time of 2 is, for example, 1/10 of the engine lubricant discharge amount.

Next, the effects of this embodiment will be explained with reference to FIGS. 1 and 2. In this embodiment, the control unit first finds the amount of fuel according to the engine speed and intake air amount by searching a map, and then multiplies this fuel amount by a predetermined ratio to find the required amount of engine lubricating oil (step S1). Next, the number of times of engine cranking per pump discharge to achieve the above engine lubricating oil amount is determined (step S2), and this interval signal is output to the step motor 11 of the engine lubrication system 8 (step S3). This causes the step motor 11 to drive the distribution pump 12, and as a result, the necessary lubricating oil is supplied to the cylinder bore 2.
It is supplied to a to 2c and second to fourth journal bearings 6b to 6d. Note that since the first journal bearing 6a is immersed in lubricating oil, there is no need to specially supply lubricating oil. Regarding the drive pulse signal for the electromagnetic pump 22 for pump lubrication, the number of engine cranking times for engine lubrication is multiplied by 10, and this is output as a drive pulse signal to the electromagnetic pump 22 (step S3). This supplies the necessary lubricating oil to the air pump 10. In this way, the amount of lubricating oil supplied per unit time by the electromagnetic pump 22 to the air pump 10 is as follows:
This amount is 1/10 of the lubricating oil supplied to the second to fourth journal bearings 6b to 6d.

As described above, in this embodiment, the air pump 10
The amount of lubricating oil discharged to engine 1 is 1/ of the amount of lubricating oil discharged to engine 1.
Since it is set to 10, it is possible to prevent excessive lubricating oil from being supplied to the air pump 10, and therefore the amount of lubricating oil consumed can be reduced accordingly. Furthermore, it is possible to suppress the lubricating oil from entering the compressed air, thereby preventing deterioration of the exhaust gas, and also preventing carbon from adhering to the area around the injection valve and the spark plug. In the above embodiments, the engine lubrication system uses a distribution pump, and the pump lubrication system uses an electromagnetic pump. However, it is of course possible to use an electromagnetic pump in the engine lubrication system.

3 to 5 are diagrams for explaining a second embodiment of the present invention, which is an example in which an air pump discharge port is added to a distribution type oil pump. In the figure, 30 is a distribution type oil pump, which mainly consists of a pump body 32 and plunger holes 32a and 3 formed in the pump body 32.
A main plunger 33 and a differential plunger 34 are rotatably and axially movably disposed within 2b.
, a sub-plunger 35 inserted into the differential plunger 34, a worm gear 39 that rotationally drives the main plunger 33, and a cam shaft 40 that adjusts the axial position of the main plunger 33. .

The worm gear 39 meshes with a gear formed on the outer periphery of the main plunger 33. Further, the cam shaft 40 is arranged in the cam chamber 32d of the pump body 32, and is rotated by a rotation lever 41.
By adjusting the axial positions of the main and differential plungers 33 and 34 using the cam stopper 40a, the discharge amount can be increased or decreased.

A pair of introduction passages 32c, 32c are bored in the pump body 32 in the axial direction, and an introduction port 32 communicates with the plunger hole 32b from each introduction passage 32c.
d is formed into three branches. Further, the pump body 32 is formed with discharge ports 38a to 38h that communicate with the outside from the plunger hole 32b. In the differential plunger 34, three pump chambers 37a to 37c formed by the large diameter portions 35a to 35d of the sub plunger 35 and an independent pump chamber 37d are formed. Further, each of the pump chambers 37a to 37d communicates with the introduction port 32d via suction ports 36a to 36d.

[0017] Of the eight outlets 38a to 38h, one of the outlets 38c and 38g serves as an air pump outlet, and the other is closed. The remaining six outlets are for the engine. The diameter of each of the discharge ports 38a to 38h and the capacity of the pump chambers 37a to 37d are such that the amount of lubricant from the pump discharge port is 0.2 for the amount of lubricant from the engine discharge port of 1. It is set to be.

The device of this embodiment also provides the same effects as the first embodiment. In other words, the amount of lubricating oil to the air pump is 0.2 for the amount of lubricating oil to the cylinder bore or crankshaft bearing of 1. Therefore, the amount of lubricating oil to the air pump is not too large, and the lubricating oil consumption is reduced accordingly. The amount of fuel can be reduced, the exhaust gas can be purified, and carbon deposition around the injection valve can be prevented.

[0019]

As described above, according to the lubrication device for an air-fuel injection type two-stroke engine according to the present invention, the engine lubrication system and the pump lubrication system are provided separately and independently, and the pump lubricant discharge amount is controlled by the engine lubrication oil. Since it is set lower than the discharge amount, it is possible to reduce the consumption of lubricating oil, and since it is possible to suppress the amount of oil mixed into the compressed air, it is possible to purify the exhaust gas and prevent carbon deposition around the injection valve. effective.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram for explaining a lubrication system for an air-fuel injection type two-stroke engine according to a first embodiment of the present invention.

FIG. 2 is a flowchart diagram for explaining the operation of the apparatus of the embodiment.

FIG. 3 is a cross-sectional side view of a distribution oil pump of a lubricating device according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional plan view of the distribution oil pump.

FIG. 5 is a sectional rear view of the distribution oil pump.

[Explanation of symbols]

1 Engines 2a to 2c Cylinder bores (cylinders) 6b to 6d 2nd to 1st journal bearings (crankshaft bearings) 7 Lubrication device 8 Engine lubrication system 9 Pump lubrication system 10 Air pump

Claims (1)

[Claims] Claim 1: In an air-fuel injection type two-stroke engine in which fuel is injected directly into the cylinder together with compressed air, the engine lubricating parts such as the inner surface of the cylinder bore and the crankshaft bearing part, and the air pump that generates the compressed air are provided with the following: A lubrication device that supplies lubricating oil, wherein an engine lubrication system that supplies lubricating oil to the engine lubrication section and a pump lubrication system that supplies lubricant oil to the air pump are provided separately, and the pump lubrication system is a unit. A lubricating device for an air-fuel injection type two-stroke engine, characterized in that the amount of lubricating oil discharged per hour is set to be smaller than the amount of lubricating oil discharged per unit time by the engine lubrication system.