JPH0731182B2 - Rapid compression combustion experimental device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention rapidly compresses air in a combustion cylinder,
The present invention relates to a rapid compression combustion experimental device that burns injected fuel.

[Prior Art] A conventional rapid compression combustion experimental apparatus has a configuration shown in FIG. In the combustion cylinder 2 equipped with the compression piston 1,
It is configured by connecting an operating cylinder 7 having an operating piston 6, and the piston 1 and the piston 6 are connected by a compression rod 5. The combustion chamber 4 of the combustion cylinder 2 is filled with air pressurized to a predetermined pressure by an air supply device 23. A fuel injection valve 24 is provided on the cylinder head 3 of the combustion cylinder 2. Further, an optical glass 25 and a reflecting mirror 26 for observing the combustion state in the combustion cylinder 2
Is provided so that the camera 27 can take an image. On the other hand, the inside of the working cylinder 7 is divided into a drive chamber 8 and a control chamber 13 by the working piston 6. The drive chamber 8 communicates with the gas container 9 and is filled with nitrogen gas at a predetermined pressure by a high pressure gas supply device (not shown). On the other hand, the brake chamber 13 is filled with hydraulic oil supplied from the hydraulic unit 19 via the pipe line 20.

When operating this apparatus, the combustion chamber 4 is filled with pressurized air, the drive chamber 8 is filled with nitrogen gas, and the braking chamber 13 is filled with hydraulic oil. Then, when the pilot hydraulic pressure is sent from the hydraulic unit 19 to the pilot valve 15 via the conduit 21,
The pilot valve is opened to discharge the working oil in the braking chamber 13, and the working piston 6 is accelerated by the filling gas. At the same time, the compression piston 1 is also accelerated and the air in the combustion chamber 4 is rapidly compressed. When the compression piston 1 reaches the top dead center, fuel is injected and burned. Then, the combustion state is photographed by the camera 27.

However, in this case, in order to prevent vibration of the observation optical system and the like, it is necessary to mitigate shocks during deceleration and stop. For this purpose, operating spacers 35 and 36 each having a conical inner shape are attached to the tip of the operating cylinder 7. Thus, when the working piston 6 advances and the shoulder of the piston enters the spacer 35, the hydraulic pressure in front of the piston rises and the piston is gradually decelerated. The front surface of the piston collides with the working cylinder and stops. After the end of the experiment, the pilot hydraulic pressure is drained, the pilot valve 15 is closed, hydraulic oil is supplied from the pipe line 20, and the pistons 6 and 1 are returned to the start position.

[Problems to be Solved by the Invention] However, the conventional technology utilizing the throttling effect of the braking spacer as a means for decelerating the piston in the latter half of the compression stroke has the following problems.

Since the braking characteristics greatly change depending on the shape of the spacer, it is generally necessary to carry out many experiments by trial and error to determine the shape.

Since the optimum spacer shape differs depending on the air pressure filling the combustion chamber, the nitrogen gas pressure filling the drive chamber, etc., it is necessary to replace the spacer when the experimental conditions are significantly changed.

Since the working piston collides with the working cylinder when the piston reaches the top dead center and stops, a large impact force is generated even when the piston speed immediately before the stop is considerably low.

It is an object of the present invention to provide a rapid compression combustion experimental device capable of solving the above problems.

[Means for Solving the Problems] In the rapid compression combustion experimental apparatus of the present invention, the compression piston provided in the combustion cylinder is driven by high-pressure gas, and
In a rapid compression combustion experimental apparatus provided with a braking cylinder that brakes the speed of the compression piston by hydraulic pressure, for hydraulic fluid discharge in which the opening is fully closed when the compression piston advances to the top dead center position in the braking cylinder. In addition to providing a port of, a control valve that reduces the opening area of the hydraulic fluid flow passage as the compression piston advances and the pilot valve that opens upon receiving a compression operation command in the hydraulic fluid discharge system from this port, The control valve is characterized in that a mechanism for continuously changing the relationship between the stroke of the compression piston and the opening area of the hydraulic oil flow path of the valve is incorporated.

[Operation] Since the control valve that can continuously change the relationship between the piston stroke and the opening area of the valve is provided in the hydraulic oil discharge system from the braking cylinder, the optimum braking state is always maintained against changes in operating conditions. It can be easily realized.

Further, the braking cylinder is provided with a hydraulic oil discharge port whose opening is fully closed when the piston advances to the top dead center position, so the piston is stopped via hydraulic pressure. Vibration and stress of members can be relaxed.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. In the conventional structure, two pistons constitute a combustion chamber, a drive chamber and a braking chamber, whereas in this embodiment, three pistons are used.
The two pistons are arranged on the same axis, and their functions are divided. That is, the compression piston 1 constitutes the combustion chamber 4 together with the combustion cylinder 2 and the cylinder cover 3, and the drive piston 6 is the drive cylinder 7 and the braking cylinder 12.
The drive chamber 8 is formed with the end of the brake cylinder 11, and the braking piston 11 is formed with the braking cylinder 12 as the braking chamber 13. The three pistons are connected by a compression rod 5 and a tension rod 10, respectively. Then, as in the conventional case, the combustion chamber 4
The interior of the brake chamber 13 is filled with air, the drive chamber 8 is filled with nitrogen gas, and the brake chamber 13 is filled with hydraulic oil. In this case, the clearance between the braking cylinder 12 and the braking piston 11 is set to the minimum required to maintain the sliding function. Further, a small amount of hydraulic oil is supplied to the tip of the braking cylinder 12 through the conduit 22.

Two hydraulic fluid discharge ports 14 are provided at symmetrical positions near the top dead center of the braking cylinder 12, and a pilot valve 15 is provided at each outlet. Further, a conical cam 18 is fixed to the rear end of the braking piston 11, and the driving rollers of the two two-way control valves 17 fixed to the braking cylinder 12 are in contact with the cam 18. The hydraulic oil outlet of the pilot valve 15 and the hydraulic oil inlet of the two-way control valve 17 are connected by a pipe line 16.

The structure of the two-way control valve 17 will be described with reference to FIG. Disc 28
A spool 29 is fitted inside. The spool 29 is formed with a conical portion 29b following the lower end cylindrical portion 29a, and the opening area of the hydraulic fluid flow passage is proportionally reduced as the spool moves upward. 30 is an adjusting rod, and the chamfered part is on the upper end.
30a has a collar 30b formed below, and the lower end is a male screw
It is 30c. And the spool 29 is the adjusting rod brim 3
It is in contact with 0b and is pressed to the roller side by the spring 31. 32
Is a roller leg having a roller 33 attached to its lower end, and a female screw 32a screwed onto the male screw 30c is provided at its upper end. Then, in a state where the adjusting rod 30 is screw-engaged, it is prevented from rotating by a stopper 34. In this way, by rotating the adjusting rod 30 and changing the distance between the roller 33 and the spool 29, the relationship between the roller position and the opening area can be arbitrarily set within a predetermined range.

The operation status of this embodiment will be described below.

In operation, the combustion chamber 4 is filled with air, the drive chamber 8 is filled with nitrogen gas, and the braking chamber 13 is filled with hydraulic oil, as in the conventional case.

When the pilot oil pressure is sent from the hydraulic unit 19 through the hydraulic pipe 21, the pilot valve 15 is opened, the working oil in the braking chamber 13 is discharged from the port 14, and each piston is accelerated. piston
When 11 is in the latter half of the stroke, the roller 33 in contact with the conical cam 18 starts to move, and the spool opening area of the two-way control valve 17 gradually decreases to decelerate the piston. When the piston further advances and reaches the position where the shoulder portion of the braking piston 11 closes the discharge port 14, the hydraulic oil in the braking chamber 13 stops flowing out there, and the piston stops. In the meantime,
FIG. 3 conceptually shows changes in the opening area of the pilot valve 15, the two-way control valve 17, and the discharge port 14 with respect to the stroke of the piston 11. Up to about 50% of the piston stroke, the piston is accelerated by increasing the opening area of the pilot valve, and when it exceeds about 50%, the piston is decelerated by decreasing the opening area of the two-way control valve. Decelerates and stops when the opening area decreases.

In this process, when the distance between the roller and the spool of the two-way control valve is set long, the change in the opening area of the two-way control valve becomes as shown in (a) in FIG. When is set to be short, it becomes as shown by (b) or (c) in the figure. In the case of (a), since the two-way control valve decelerates until the speed becomes zero, almost no shock occurs at the time of stop, but the time until the compression operation is completed becomes long. On the other hand, in the case of (c), a large deceleration is generated immediately before the stop because the piston speed is rapidly decelerated from the state where the piston speed is high immediately before the deceleration is started at the discharge port. However, the compression operation time can be shortened.

In the actual device, the air pressure and compression ratio to fill the combustion chamber,
Since the progress of the piston speed varies depending on the pressure of nitrogen gas filling the drive chamber, clay in the hydraulic oil in the braking chamber, etc., the compression operation time should be the shortest within the range where the shock at the time of stop can be tolerated according to each condition. In addition, the progress of the opening area of the two-way control valve is adjusted between the above (a) and (c).

After the piston reaches the top dead center, a small amount of hydraulic oil leaks from the clearance between the braking cylinder 12 and the braking piston 11. The piston can be maintained stationary at the top dead center position by supplying the piston to the piston.

After the experiment was completed, the pilot valve 15 was closed and the hydraulic line
Supply hydraulic oil from 20 to return the piston to the start position.

[Effects of the Invention] The present invention is as described above, and has the following effects.

(1) Since the speed of the piston is controlled by changing the opening area of the valve whose flow rate characteristic is relatively clear, the design of the braking function becomes easy. Therefore, it is possible to omit the conventional trial and error modification.

(2) The braking characteristics can be adjusted without disassembling the piston or cylinder.

(3) Since the relationship between the piston stroke and the opening area of the valve can be arbitrarily set, it is possible to easily easily realize an optimum braking state with respect to changes in operating conditions.

(4) When the piston reaches the top dead center, the piston is stopped via hydraulic pressure so that the piston and the cylinder do not collide with each other, so that the vibration and the stress of the member at the time of the stop can be relieved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the device of the present invention, FIG. 2 is a vertical sectional view of a two-way control valve, and FIG. 3 is a pilot valve with respect to a piston stroke, two-way control valve and opening of a cylinder discharge port. FIG. 4 is an explanatory view showing a change situation of the area, and FIG. 4 is a vertical sectional view of a conventional rapid compression combustion experimental apparatus. DESCRIPTION OF SYMBOLS 1 ... Compression piston, 2 ... Compression cylinder, 6 ... Driving piston, 7 ... Driving cylinder, 11 ... Braking piston, 12 ... Braking cylinder, 14 ... Hydraulic oil discharge port, 17 ... Two-way control valve, 18
… Conical cam

Claims (1)

[Claims] 1. A rapid compression combustion experimental apparatus in which a compression piston provided in a combustion cylinder is driven by high-pressure gas and a braking cylinder for braking the speed of the compression piston by hydraulic pressure is provided. A port for hydraulic oil discharge is provided so that the opening is fully closed when the piston advances to the top dead center position, and the hydraulic oil discharge system from this port opens with a compression operation command and the above-mentioned compression valve. A control valve is provided in which the opening area of the hydraulic oil flow passage decreases as the piston advances, and this control valve continuously changes the relationship between the stroke of the compression piston and the opening area of the hydraulic oil flow passage of the valve. A rapid compression combustion experimental device characterized by a built-in mechanism for changing.