RU181068U1 - Gas distribution mechanism of a piston internal combustion engine with a controlled valve lift - Google Patents

Abstract

The utility model relates to the field of engine building; can be used for the modernization of piston engines with spark ignition with an upper separate arrangement of the intake and exhaust camshafts. In the classical scheme of such a gas distribution mechanism, it is proposed to install a lever pusher with an arcuate upper surface and a roller that is moved along the surface of the pusher with a fork between the camshaft cam and the intake valve hydraulic compensator. The plug is mounted on the camshaft bearings and can be rotated about its axis. When moving the roller along the surface of the lever pusher, the maximum valve lift value changes with a constant opening time. Depending on the direction of rotation of the shaft, the maximum valve lift (maximum cylinder filling) can shift in the phase of the cycle or in the direction of delay, or in the direction of advancing the valve opening. Accordingly, you can work out the working process of the engine or the Atkinson cycle, or the Miller cycle. The utility model allows to increase the efficiency of engines with spark ignition when operating at partial loads.

Description

The invention relates to engine building, in particular, to internal combustion engines.

In spark ignition engines, power control is mainly due to changes in the filling of the cylinders with a fresh charge using a throttle valve located in the intake system at a certain distance from the cylinder inlet. When covering the throttle (when lowering the power), the gas velocity decreases through the intake pipe, which leads to a noticeable decrease in the level of the gas-dynamic state of the gas mixture at the time of ignition, and, as a result, to insufficient turbulent combustion rate. To increase the intensity of combustion, it is necessary to create a more active rich mixture, which significantly reduces the efficiency (efficiency) of the internal combustion engine (ICE) from chemical burning of fuel.

To obtain the highest level of gas dynamics, it is desirable to control the filling by throttling the flow at the inlet to the cylinder by changing the flow area of the intake valve. In this case, when the filling is reduced, the gas dynamics intensity is preserved in the best way to the beginning of combustion.

Known gas distribution mechanisms (timing) with filling control systems by changing the lift height and the duration of the intake valve opening can be divided into mechanical, hydromechanical and electromagnetic (see Internal Combustion Engines. Book 2: Dynamics and Design: Textbook for high schools: V 3 book / Edited by: V.N. Lukanin and M.G. Shatrov. - 2005. - 399, [1] p.: ill. - Bibliography: p. 396; RU 2187004 C1, IPC 7 F02В 23 / 08, 2002; RU 2232906 C1, IPC 7 F02В 23/08, 2004).

For analogues, it is possible to take timing with mechanical control systems for valve lift height. In such systems, in the classic design of the gas distribution mechanism, intermediate parts with springs are installed between the camshaft cam and valve set to ensure shock-free operation of the mechanism. The presence of additional springs complicates the design, reduces the reliability of the mechanism.

The closest technical solution is the BMW Valvetronic mechanical system, adopted as a prototype, implemented in the production of engines. However, it has a rather complicated design of the intake valve actuator compared to traditional gas distribution systems and includes additional electromagnetic shaft, levers, and springs (see Internal Combustion Engines. Book 2: Dynamics and Design: Textbook for High Schools: В 3 кн. / Под Ed .: V.N. Lukanina and M.G. Shatrova. - 2005. - 399, [1] p.: ill. - Bibliography: p. 396).

The objective of the invention is to increase the efficiency of engines with spark ignition when operating at partial loads.

The problem is achieved by the fact that a gas distribution mechanism with a controlled valve lift height is proposed, consisting of a camshaft with a cam and a valve kit, and a lever pusher with an arcuate upper surface, a concentric initial cam circumference, and a roller on this surface, having the ability to move with a fork, which is mounted on the camshaft bearings with the possibility of rotation relative to its about and.

The proposed gas distribution mechanism (timing) with a controlled opening height of the valve does not have additional springs and requires relatively simple structural changes to the traditional valve opening drive in the gas distribution mechanisms with an upper separate arrangement of the intake and exhaust camshafts.

In the proposed timing, between the cam of the intake camshaft and the valve kit (including the hydraulic compensator), a lever pusher with an arcuate upper surface, a concentric initial cam circumference, and a roller that is moved along the upper surface of the lever pusher with a fork rotated relative to the camshaft axis are mounted on the axis.

The proposed utility model is illustrated by images, where:

1 - cam inlet camshaft,

2 - roller

3 - axis

4 - lever pusher,

5 - valve kit

6 - plug

7 - camshaft bearings.

In FIG. 1 schematically shows the proposed mechanism, including a cam 1 of the intake camshaft, a roller 2, a lever pusher 4 mounted on the axis 3, and a valve kit 5. The roller 2 is moved along the pusher 4 with a fork 6 mounted on the camshaft bearings 7 (Fig. 5, Fig. 6). The cam, roller and the distance from the swing axis of the lever pusher to the valve axis are made in full size. The diameter of the initial cam circumference, equal to 32 mm, is selected with reference to the cam of the camshafts of four-cylinder small engines. The height of the cam top is 4 mm and the diameter of the roller is 8 mm for structural reasons. With these sizes, graphically in FIG. 2 - FIG. 4, valve movements are determined depending on the position of the roller. When moving the roller along the lever pusher at angles from -8 to + 10 ° relative to the middle position, the valve lift height changes from 3 mm (minimum lift) to 8.5 mm (maximum lift). Such a change in valve lift will allow a wide range to change the engine fill factor, which is acceptable for controlling power over a wide range.

In the proposed timing, a change in the height of the valve lift is accompanied by a shift in the start of opening and end of closing of the valve with a constant duration of its opening. In the direction of rotation of the camshaft shown in FIG. 2 - FIG. 4, when the cam runs onto the lever pusher from the side of its combined end, an increase in the valve lift height is accompanied by a shift in the start of its opening to the delay side to a maximum value of 18 ° camshaft rotation, which corresponds to 36 ° crankshaft rotation in a four-stroke cycle. Such a shift of the intake valve opening phase to the delay side can be used to organize the Atkinson cycle workflow. With a delay in closing the intake valve with increasing filling, gas will be thrown from the cylinder into the intake pipe, which will lead to a decrease in pressure and temperature at the end of compression, and, as a result, to a decrease in the likelihood of knocking at high engine loads. At the same time, at low fillings (low engine loads), a decrease in the flow area of the valve gap will lead to an increase in the gas dynamics intensity and, as a result, to the possibility of stable and fast burning of a more economical lean mixture and higher engine efficiency. This process is more efficient for supercharged engines.

When the camshaft rotates in a direction opposite to the direction of rotation shown in FIG. 2 - FIG. 4, when the cam runs onto the lever pusher from the axis side, it is possible to organize the engine workflow according to the Miller cycle. With an increase in the valve lift height (with an increase in cylinder filling), its earlier opening and closing occurs. With large fillings, the valve closes before the piston arrives at bottom dead center. In this case, after closing the valve, the pressure and temperature in the cylinder will decrease as the piston moves down according to the laws of polytropic expansion, and with the subsequent compression of such a gas mixture lower pressures and temperatures will be obtained at the time of ignition, which will reduce the engine’s tendency to detonate. This will increase the compression ratio according to the detonation conditions and obtain a higher efficiency of such engines compared to engines operating in the Otto cycle. In addition, at low fillings, a decrease in the cross section of the valve gap will make it possible to burn lean mixtures more efficiently due to more intensive gas dynamics and further increase the efficiency of such engines operating according to the Miller cycle.

The utility model allows to increase the efficiency of engines with spark ignition when operating at partial loads.

Claims (1)

A gas distribution mechanism with a controlled valve lift height, consisting of a camshaft with a cam and a valve kit, and a lever pusher with an arcuate upper surface, concentric with the initial cam circumference, and with a roller on this surface that can move when help fork, which is mounted on the camshaft bearings with the possibility of rotation about its axis.

Images