JPS63201306A - Valve system with variable valve timing - Google Patents

Abstract

PURPOSE:To enable an engine operation corresponding to engine speed by providing a tappet mechanism in which a piston for varying the stroke of a push-rod receiver is fitted in a tappet body in which said push-rod receiver is also slidably fitted, and a cam device. CONSTITUTION:A tappet body 1 is slidably fitted in a cylinder block 6, and the bottom end part of a push rod 5 is supported by a push-rod receiver 2 which is slidably fitted in the tappet body 1. The receiver 2 is energized upward by means of the spring force of a spring 3 and the hydraulic pressure of a hydraulic chamber A formed on the lower part of a piston 4 which supports the bottom end of the spring 3, and the stroke H between the receiver 2 and the piston 4 can be changed in reverse proportion to the magnitude of the pressure of the hydraulic chamber A. And, the feeding/discharging of oil to and form the hydraulic chamber A is controlled by a three-way solenoid valve 8 while its hydraulic pressure is controlled by a hydraulic pressure proportional control valve 10, and the valves 8, 10 are controlled by a controller 11 in accordance with an operating condition.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a valve operating device that opens and closes the intake and exhaust valves of an internal combustion engine, and relates to a variable mechanism for the lift (valve timing) of the intake and exhaust valves. .

(Conventional technology) It is difficult to obtain valve timing (valve lift) that meets all engine operating conditions.

In most cases, the valve timing is set to be optimal around the maximum torque point and rated point, but in order to optimize it over a wide rotation range, the well-known oil tappet is set as shown in Figure 6. As shown in FIG. 7, a variable valve timing device is used to obtain valve timing that corresponds to the engine rotational speed.

In the figure, a indicates a tappet body, and the tappet body a is slidably mounted on a cylinder block i. Reference numeral b denotes a plunger fitted into the tappet body a, and a bushing rod holder C that supports the end of the bushing rod d is fixed to the plunger b. Engine oil is supplied to the plunger chamber B formed in the plunger b from the oil gear j of the cylinder block i.

A check valve e is provided between the plunger chamber B and the oil working chamber A of the tappet body a, and the check valve 6 is configured such that the tappet body a is raised by the cam h, and the oil pressure in the A chamber is higher than that in the B chamber. In this case, the hydraulic pressure in the chamber A exceeds the spring force of the spring f, and the check valve e rises.
It is designed to stop the oil from flowing out from the A chamber.When the engine is at low speed, the rate of pressure rise dP/dt in the A chamber is small, so the rise of the check valve e is slow, which prevents the oil from flowing out from the A chamber. , H becomes small, and at high speed, the pressure increase rate dP
/dt is large.

The valve timing is adjusted as shown in FIG. 7 by taking advantage of the fact that the check valve e rises faster, less oil flows out from the A chamber, and H becomes larger.

(Problem to be solved by the invention) In the variable valve timing device described above.

Although the purpose of this method is to obtain valve timing that corresponds to the engine rotation speed, it has the disadvantage that the amount of oil lost also changes depending on the oil temperature, so the valve timing also changes.

In addition, it is currently not possible to respond to decompression at startup, EGR (exhaust gas re-vaIl) to improve startability, reduction, high speed, early intake valve closing timing, and high output of the engine due to mirror cycle. It is.

The object of the present invention is to solve the above-mentioned problems and provide a variable valve timing device having a function of operating an engine in an optimal state depending on the purpose.

(Means and effects for solving the problem) The present invention has been made in view of the above problems, and includes a push rod holder that is slidable above the tappet body, and a spring that connects the oil pressure in the hydraulic chamber to the bottom of the tappet body. A tappet device is provided with a piston that slides with a balance between pressure and spring force, and has a function of changing the distance ml (variable stroke) between the lower end of the bushing rod receiver and the upper end of the piston in inverse proportion to the hydraulic pressure at the lower end of the piston.
A three-way solenoid valve that supplies and drains oil to the hydraulic chamber of the tappet device based on instructions from the controller, a check valve that prevents the supplied oil from flowing backwards, and oil pressure control from the engine's oil gear (proportional to the engine rotation speed). It is comprised of a hydraulic proportional Mlll valve that performs pressure regulation) and switching between the oil gear gallery and the separately installed oil pump based on instructions from the controller. Oil is supplied to the hydraulic chamber before the intake and exhaust valves begin to open, and the piston receives the hydraulic pressure and rises to a position balanced with the spring force.

Even if the tappet body is pushed up by the cam, the push rod receiver does not rise because the opening force is much greater than the spring force, and it starts to rise the moment the upper end of the piston hits the lower end of the push rod receiver.

Oil is drained from the hydraulic chamber as it descends.

Therefore, if the variable stroke is small, the valve will start opening earlier,
If it is large, it will start to open later.By controlling the supply hydraulic pressure, valve lift can be performed without changing the cam profile, by combining the cam profile and this device according to the purpose.

This allows the engine to operate in optimal conditions.

(Example) Next, an example of the present invention will be described based on the drawings. FIG. 1 shows the main points of the variable valve timing device of the present invention.

In Fig. 1, 1 is the tappet body and the cylinder block 6
A bushing rod holder 2 for supporting a bushing rod 5 is slidably installed in the upper part of the tappet body 1.

It is slidably installed below the tappet body 1 so that the distance between the lower end of the bushing rod holder 2 and the upper end of the piston 4 becomes a variable stroke H via a spring 3.

Hydraulic pressure is applied to the hydraulic chamber A formed by the tappet body 1 and the piston 4 before the tappet body 1 rises, and the piston 4 reaches a point where the hydraulic pressure and the spring force of the spring 3 are balanced.
is on the rise.

The variable stroke H changes in inverse proportion to the magnitude of the pressure applied to the hydraulic chamber A.

Even if the tappet body 1 is raised by the cam 7, the spring 3
Since the spring force of is smaller than the valve opening force of the valve spring, the push rod 2 does not rise until the bushing rod holder 2 and the piston 4 are integrated, and once they are integrated, they rise and the valve begins to open. Therefore, if the variable stroke H is small, the valve will start opening sooner, and if it is larger, the valve will start opening later.

Oil supply and drain to hydraulic chamber A is done by controller 1.
The hydraulic pressure is controlled by a three-way solenoid valve 8 that operates based on an instruction from a controller 11, and a hydraulic proportional control valve 10 that operates based on an instruction from a controller 11.

The three-way solenoid valve 8 has the function of supplying oil when the tappet body l rises and draining it after descending, and the check pulp 9 prevents oil from the hydraulic chamber A from draining while the push rod receiver 2 is moving up and down. It is provided between the three-way solenoid valve 8 and the hydraulic proportional control valve IO.

Figure 2 shows the cam profile and valve lift when the variable valve lift device and cam profile are combined to improve engine startability, improve performance, ~o, 1 measure, and increase engine braking force.

Ill When starting at a low temperature, in order to improve engine startability and prevent battery deterioration, it is necessary to crank the engine (decompression operation) with the intake valve slightly open until the engine oil pressure rises. Therefore, as shown in the diagram, high pressure ("vlok") is required from the cam profile and separate oil pump.
+r/cj) oil to the tappet, cranking with H=0, and after the engine oil pressure rises, stop oil feeding from the separate oil pump, and switch to oil feeding from the engine oil gear 1 Normal. drive.

In this case, 11-MAX due to the center force of spring 3.
, and can now be operated without any problems during normal operation.

(2) In order to improve engine performance, it is necessary to change valve timing in accordance with engine rotation speed. The stroke H is adjusted so that the valve timing is optimal for achieving optimal suction efficiency from low speeds to high ranges, and the valves are opened early at high speeds and opened later at low speeds.

(3) To improve startability and reduce noise, EGR operation opens the exhaust valve during the intake stroke and inhales a portion of the exhaust gas. This increases the intake air temperature, increases inertness, and lowers the explosion temperature. , It has the effect of improving startability, No. It is accompanied by a decrease in engine performance, so it is better not to implement it if EGR operation is not required. You can freely perform EGR operation or normal operation depending on whether EGR is necessary or not. Immediately before the intake valve shown in the figure closes, the exhaust valve opens using a two-stage exhaust cam with a lift and high pressure (10 kg/d) from a separate oil pump.
), and set it to H-0 during EGR. 1. During normal operation, switch to oil supply from the engine's oil gear rally, and set H=M.
Make it AX.

(4) To increase engine braking force.

A method is known in which the exhaust valve is opened near the upper compression rudder point so that the expansion force is not transmitted to the piston, and the Jacobs glue tarp is widely used, but it is very expensive. Therefore, the two-stage exhaust cam that has a lift at compression top dead center as shown in the figure is combined with a variable valve timing device to achieve this objective at low cost. When leaving the plane, make it H-0 by supplying high-pressure oil (+r/cd to #10) from a separate oil pump or engine gear; during pipe operation, stop supplying engine oil or supply from the engine oil gear. (-MAX).

The above description has been made of the case where this invention is applied to a tappet, but of course it is also possible to apply it to other valve train parts. shows the case where it is applied to a crosshead. In both cases, the valve timing is the same as for tappets.

It is possible to change the pulp pattern.

(Effects of the Invention) Since the present invention is constructed as described above, by using the variable valve timing device and the cam profile in combination, 1. Decombination operation and EGR operation can be performed at low cost without sacrificing the performance during normal operation.

Enables increased engine braking power! In addition, it is possible to operate the engine according to the engine rotation speed.

It can also improve engine performance.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, showing a variable valve timing device applied to a tappet, and FIG. 2 shows a valve lift situation when the device is combined with a cam profile.
Figures 3(a), 3rd issue), 4 and 5 respectively show examples in which the present invention is applied to other valve train parts, and Figures 6 and 7 show conventional Show the device. 1... Tappet body, 2... Pusherondo receiver,
3...Spring, 4...Piston. 5...Pufscherrod, 6...Cylinder block. 7...Cam, 8...Three-way solenoid valve. 9...Check pulp, 10...Hydraulic proportional control valve. 11... Controller. 1:l A...Hydraulic chamber, H...Variable stroke. Patent applicant Komatsu Ltd. Agent (patent attorney) Osamu Matsuzawa Figure 3 (α) Figure 3 (b) Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A hydraulic circuit section consisting of a hydraulic proportional control valve, a three-way solenoid valve, and a check valve, which is controlled by a controller that controls engine performance, and a tappet mechanism and cam device consisting of a tappet section having a piston, an oil chamber, and a spring. A variable valve timing valve operating system that enables decompression operation, EGR operation, increased engine braking force, and engine operation corresponding to engine speed without sacrificing engine performance.