Electromechanical hydraulic variable valve timing system in internal combustion engines

Abstract

In variable valve timing systems, whether CVVT or VVT, there is a serious problem that despite the change in the opening and closing times of the valves, the amount of opening and closing of the valves does not change in terms of degrees of the crankshaft and does not reach maximum efficiency. In this design, the camshaft acts as the main driver to open the valves and the valve spring closes them, and for each valve there is a solenoid valve that is controlled by the ECU. Special hydraulic tappets have been designed whose oil quantity is controlled by the solenoid valve. The solenoid valves are normally open and close the oil path upon receiving a command from the ECU. The shape and design of the camshaft cam are designed in such a way that maximum advance and retardation are considered for each valve.\nAs a result, at all engine speeds, the ECU calculates the exact time to open and close the valve for maximum efficiency and power and issues the valve opening and closing command to the solenoid valve.\nApplications of this invention are in gasoline and diesel internal combustion engines, passenger car and truck engines, generators, and racing car engines.

Description

In the name of the Almighty Description of the invention 1. Title of the invention Electromechanical hydraulic variable valve timing system in internal combustion engines 2. Technical field of the relevant invention Mechanical engineering, four-stroke piston cylinder internal combustion engines, intake and exhaust valve systems 3. Technical problem and statement of the purpose of the invention In four-stroke internal combustion engines with cam designs, the intake (air) and exhaust (smoke) valves open and close only at a specific engine speed, creating maximum efficiency. The more the engine speed changes, the less efficient the engine is, which is why engineers have invented a system in new engines that changes the timing according to the engine speed. The purpose of providing such systems is to increase engine efficiency in all operating conditions, including different engine speeds and different environmental conditions. In older engines, experts have selected the appropriate camshaft with the appropriate timing, taking into account the conditions for which the engine is intended, but of course this has many limitations, for example, the so-called high-grade camshaft is very suitable for racing and increasing efficiency at high speeds, but this increase in power at high speeds comes at the cost of a significant decrease in torque and power at mid and low engine speeds, and practically makes the engine unusable at low speeds (for example, in the city). In the variable valve timing (VVT) system, the opening and closing times of the intake and exhaust valves change according to the engine speed to obtain maximum efficiency and power at high and low engine speeds. Various models of this system have been designed and manufactured, in some cases, such as the EF7 engine, the air valve shaft is continuously retarded and advanced by the CVVT mechanism. If the valve shaft is advanced, the intake valves open earlier and close earlier, and if it is retarded, the valves open later and close later, which reduces the volumetric efficiency of the engine. In the latest type, electromagnetic valves are used, which eliminates the valve shaft and the power transmission mechanism by the timing belt. In the event of an electrical fault for any of the valves, the cylinder corresponding to that valve will completely fail. In internal combustion engines, the more the volume of the engine cylinder can be filled with a mixture of fuel and air, the greater the volumetric efficiency of the engine. In this innovative design, changing the opening and closing times of the intake and exhaust valves helped increase the volumetric efficiency of the engine. 4. Prior knowledge and history of existing developments The trend of increasing engine efficiency, reducing fuel consumption and minimizing emissions has been continuous over time. One of the things that has been done and has made a huge difference in increasing engine power and torque is the use of a system called VVT, which increases volumetric efficiency at high revs. This system is known as Variable Valve Timing. If the engine speed increases, the number of times the valves open and close will also increase. Given that air and gasoline are drawn into naturally aspirated engines (which are not equipped with a turbocharger system) due to the creation of a relative vacuum and the piston moving down inside the cylinder, when the speed of opening and closing the air valve increases, the opportunity for the air and gasoline mixture to enter the cylinder will decrease. In other words, at high speeds, the speed of opening and closing the valve increases so much that the air and gasoline mixture cannot enter the cylinder in the required amount, which causes volumetric efficiency to decrease. According to the diagram (Figure 1), if the engine speed increases beyond a certain limit, the engine torque and power will decrease, which will reduce efficiency and increase fuel consumption and environmental pollution. For example, the engine of the Renault Thunder is 1600 cc and does not have a VVT system, and has a power of 105 horsepower and a torque of 140 Nm. The same engine is installed on the Renault Megane 1600, with the difference that it is equipped with a VVT system related to the intake camshaft. By installing this system on the cylinder head of the Renault Megane 1600 engine, its power has reached 115 horsepower and its torque has reached 152 Nm, which means that the value of these two indicators, power and torque, has increased by about 10%. Alfa Romeo was the first to install this system on its Spider model in 1980. This car had a 2-liter engine with a completely mechanical VVT system, and Alfa Romeo later used the same system on the Quadrifoglio and Giampaolo models in the 1970s. In some engines, a continuously variable valve timing system (CVVT) is installed on the intake and exhaust camshafts. The CVVT mechanism changes the timing of the intake and exhaust valves in relation to the load and engine speed, thereby adjusting it to the best possible condition. The CVVT system is operated by oil pressure, which is controlled by the OVC oil control valve, which is in turn controlled by the ECM electronic control unit. 5. Providing a solution to the existing technical problem along with an accurate, sufficient and integrated description of the invention. Considering that the more the engine cylinder volume can be filled with a fuel-air mixture, the more the engine's volumetric efficiency increases. In relation to this issue, VVT and CVVT systems have been designed and manufactured in the valve timing system. The VVT ​​system advances or retards the air or exhaust valve stem in a single step, and in the CVVT system, this is done continuously. For example, in the Haima vehicle, which has a VVT system installed on both the intake and exhaust camshafts, at a certain engine speed, the engine ECU issues a single-step valve timing delay or advance command, which increases the volumetric efficiency of the engine and reduces the load on the engine. In the EF7 engine, the CVVT system, which is located on the intake camshaft, advances the intake camshaft at high speeds at the command of the ECU to increase the engine's volumetric ratio. However, the weakness of these systems is that by advancing the camshaft for the opening time of the valve, the valve closing time is advanced by the same amount and the valve will close earlier, or by retarding the camshaft, the valve will open later and close later.This will not achieve maximum volumetric efficiency. The solution to this problem is that in this design, the camshaft is used as the main actuator to open the valves and the valves are closed by a spring, and for each valve, a solenoid valve controlled by the ECU is placed. Special hydraulic tappets are designed (according to the drawing) whose oil quantity is controlled by the solenoid valve. The solenoid valves are normally open and close the oil path upon receiving a command from the ECU. The camshaft cam design has been changed so that for the maximum and minimum engine speed at which each of the inlet or outlet valves must be advanced or retarded (for example, 60 degrees of crankshaft rotation) it has been changed. The basic idea is that in the engine idle state, where there is no need for air valve advance but rather for its retardation, when the cam (advanced) presses on the hydraulic tappet, the oil in the cylinder and the tappet piston reaches the solenoid valve through a channel built into the cylinder head and is discharged there in the cylinder head, meaning that as the tappet moves down, only the oil below it is discharged and the valve is still held closed by the springs (i.e. valve retardation or delayed valve opening). When the engine ECU detects that the valve needs to be opened, it instructs the solenoid valve and the solenoid valve closes the oil outlet path, resulting in oil being trapped in the hydraulic tappet, causing the cam force to be transmitted to the tappet and to the valve, and the valve opens. At high rpm, the engine ECU issues a command to close the solenoid valve earlier, depending on the engine speed, which causes the valve to open earlier. The result is that depending on the engine speed and the load on it, the ECU calculates the exact time to open and close the valve for maximum efficiency and power, based on information from the engine speed sensor and other sensors, and issues a command to open and close the valve to the solenoid valve. This results in reduced fuel consumption and increased engine efficiency at different rpm. 6. Explanation of shapes, maps and diagrams Hydraulic lifter: This lifter is specially designed to perform this function. Like the hydraulic lifter of the EF7 engine and other vehicles, this lifter is located in the cylinder head, but it has an inlet and an outlet for oil from the cylinder head. In addition to its outer body, the lifter contains a cylinder and piston assembly, a one-way valve, and a spring. The upper surface of the lifter body is in contact with the camshaft cam, and the lifter cylinder is in contact with the valve head. Type-Pit Assembly: According to the figure and drawing (numbers 2 and 3), the cylinder and piston with spring and one-way valve are located inside the type-Pit body. Tippet body: This part is located in the cylinder head, its upper surface is in contact with the cam, and it has two channels, one for oil entry and one for oil exit, which are arranged in a groove around it so that oil can flow when the tippet rotates, as shown in Figures 4 and 5. Cylinder and piston inside the headstock: According to the figure and drawing (numbers 6 and 7), these parts are located inside the headstock body. The piston, under spring pressure and oil pressure, always contacts its upper surface from inside the headstock and has a channel and a one-way valve through which oil can enter the headstock channel from the channel built into the headstock, and by passing through the piston channel, enter the cylinder chamber. The oil cannot return from the entered path because the valve was one-way and was held in place by spring pressure. Cylinder: According to the figure and drawing (numbers 8 and 9), this part acts like a piston in the body of the typewriter, and the piston assembly with the spring and valve is placed inside it. There is a channel and a groove on the cylinder body for oil flow. Position of the tippet and its internal components when the valve is closed: According to the diagram (No. 10) of the general path of oil entry and exit and control, when the cam pressure is removed from the tippet surface, the valve spring and tippet spring place the assembly at the highest level. Oil under pressure from the engine oil pump enters the tippet input oil through the cylinder head duct. The spring inside the tippet holds the piston from inside the tippet to the top and the cylinder on the valve head under pressure. The oil entering the tippet enters the piston duct and after passing through the one-way valve, enters the tippet cylinder, and the oil exits the output oil duct and moves towards the solenoid valve. Solenoid valve: According to the drawings (numbers 11 and 12), this part is located in the oil outlet path from the tip, like a gasoline injector, it receives an open and close command from the ECU. In the normal state of Figure 11, the solenoid needle is in the open state by the pressure of the spring (normally open), and according to Figure 12, when the command is received from the ECU, the solenoid needle moves by its coil magnet and closes the oil outlet path. With software programming, the operation strategy tables of this solenoid valve are performed for the best working mode. Pressure control valve: According to the figure and diagram (numbers 13 and 14), when the engine valve is closed and the tappet is in its highest position, the oil enters the tappet and from there to the solenoid valve and is discharged into the cylinder head. This valve is used to prevent this oil discharge from reducing the engine oil pressure. With the appropriate pressure of the spring on the ball, the oil path is kept at the appropriate pressure. How it works for valve advance and retard: According to the initial explanation, the maximum amount of advance and retard required is applied to the camshaft cam at the time of manufacture. For advance at the time of valve opening (early valve opening): This is when the engine speed is high and we want the air valve to open earlier to increase the shear time of the valves. For maximum advance, before applying the cam force to the tappet, the solenoid valve is activated by the ECU and closes the tappet oil drain path. According to the diagram (No. 15), by rotating the cam (maximum advance and retarded) on the tappet surface and applying force to it, the tappet starts to move down. The oil in the space between the cylinder and the piston is trapped by the one-way valve and the solenoid valve and directly transfers the cam force to the valve and the valve opens at maximum advance. For the retard mode at the time of closing (late valve closing): According to the diagram (number 16), this mode is for when the engine speed is high and we want to close the air valve and the exhaust valve later. In order for the valve to close at its maximum retard, the solenoid valve remains closed under the command of the ECU. As a result, by rotating the cam with the required retard value on it, the valve remains open. By rotating the cam over the tappet, the valve closes. When the valve closes, the solenoid valve returns to its previous state by the command of the ECU. For the retard mode at the time of valve opening (late valve opening): This mode is for when the engine speed is low and we want the air valve to open later, in this mode, the solenoid valve closes the oil outlet path by the ECU at a later time. As a result, when the tappet is lowered by the cam, only the oil inside the tappet is discharged and despite the tappet being lowered, the valve remains closed. Whenever the ECU issues the opening command, the solenoid valve operates and closes the oil outlet path and the valve starts to open. Solenoid valve failure: If the solenoid valve fails for any reason and does not function, the engine cylinder must be able to continue operating like a normal engine until the driver can take the vehicle to the repair shop. Given that the maximum amount of advance and retard applied to the cam by rotating the cam on the tappet, according to drawings (17 and 18) (of which drawing number 17 is the upper position of the tappet) (drawing number 18, with the lowering of the tappet and the outflow of oil, the distance between the cylinder and the piston has decreased and the valve is still closed) and that the solenoid valve path is completely open due to the fault, the oil between the cylinder and the tappet piston in the cylinder head is drained and prevents the valve from opening. This happens until the outlet duct of the tappet body has not passed through the outlet duct on the cylinder head block. As these two ducts pass each other, the trapped oil causes force to be applied to the valve and opens the valve (without advance), with the continuation of the tappet movement downward by the force of the cam, according to drawings (numbers 19 and 20) (drawing number 19, the moment the tappet duct reaches the second duct of the cylinder head) (drawing number 20, the end position of the tappet movement) The tappet duct to the second ductThe cylinder head reaches where another amount of oil trapped in the cylinder head is drained and some of the valve is closed, which is closed earlier by rotating the valve cam (without retarding the valve). According to drawings (21 and 22), the tippet passage reaches the second passage of the cylinder head and the distance between the seat and the valve decreases. 7. Advantages of the claimed invention over prior inventions 1- In VVT systems, the valve advance or retard command is applied to the valve stem in a single step. The disadvantage of this system is that the total valve opening angle is fixed, meaning that if the valve stem opens the valve 30 degrees earlier, the valve will also close 30 degrees earlier. 2- In the CVVT system, the valve advance or retard command is applied continuously to the valve stem, but it has the same drawback as the VVT ​​system. 3- In electromagnetic valve engines, the defects of previous systems have been eliminated, but in the event of an electrical fault, a broken wiring harness, or a failure of the valve magnets, the cylinder corresponding to that valve will fail for each valve. 4- In this design, all the defects of previous systems have been eliminated, and the advantage of this design is that the amount of valve advance and retardation is completely under the control of the engine ECU, meaning that the valve can be advanced when it opens and retarded when it closes, which increases the volumetric efficiency of the engine. 5- In the event of a problem with the solenoid valve, whether mechanical or electrical, the valve mechanism continues to operate, with the only difference being that the valve does not advance or retard, and the engine cylinder continues to operate like a normal engine until it reaches the repair shop. 6- In this system, the valve opening course change plan can also be applied by programming it on the ECU. 8. Implementation method for applying the invention The implementation method for using this system is to add a solenoid valve for each valve and make changes to the camshaft, cylinder head, hydraulic type, and engine ECU program. 9. Industrial application of the invention Gasoline and diesel internal combustion engines, passenger car and truck engines, generators and racing car engines, especially high-revving engines

Claims

Complaint What is claimed: Claim 1) The technical features of this design are that the amount of opening or closing of the valves is variable based on the amount of rotation angle of the vehicle engine shaft based on the engine speed. The most important innovative point in this invention is that the valves can be adjusted based on the engine speed for the opening time of advance and retard and for the closing time of advance and retard or vice versa for the air and exhaust valves to achieve maximum volumetric efficiency of the engine and minimum load on the engine. This means that each valve can be controlled from four aspects, which are: a) advance opening of the valve, b) advance closing of the valve, c) retard opening of the valve, d) retard closing of the valve. For this purpose, new parts have been designed for the vehicle engine in this invention, which include a camshaft with special and modified cams and special hydraulic tappets for each engine valve, and special hydraulic valves for each engine valve, which are activated and deactivated by the command of the engine control unit or a separate unit control unit. If this task is with the engine ECU, it will result in a change in the hardware or software program of the engine control unit.This invention is designed in such a way that if the solenoid valve fails or its wires are cut, there will be no significant disruption to the engine.

Images