Fully variable valve train with rotary plunger for internal combustion engine

Abstract

A fully variable valve train with a rotary plunger for an internal combustion engine. A motor actuates a high-pressure oil injection pump; when a timing driven electromagnetic valve connected to an oil inlet is opened, high-pressure oil enters a hydraulic cylinder; and when the force applied to a plunger by the hydraulic oil is larger than the force of a valve returning spring, the plunger is pushed to move down, so that a valve is opened. When the valve is required to be return, the timing driven electromagnetic valve connected to the oil inlet is closed, and the timing driven electromagnetic valve connected to the oil inlet is opened; the valve moves up under the action of the valve spring, pushing the plunger to move up and thereby discharging the low-pressure oil out of the hydraulic cylinder, then the plunger and the valve return to the initial positions.

Claims

1. A fully variable valve train for an internal combustion engine, the fully variable valve train comprising: an oil reservoir; a high-pressure oil rail in fluid communication with the oil reservoir via a supply pipe; and a hydraulic cylinder including: a high-pressure oil inlet pipe adapter in fluid communication with the high-pressure oil rail via an oil inlet pipe; a high-pressure oil return pipe adapter in fluid communication with the oil reservoir via an oil return pipe; a rotary plunger disposed in a rotary plunger chamber; and an adjusting plunger disposed in an adjusting plunger chamber; an oil-inlet timing driven electromagnetic valve arranged in the oil inlet pipe; an oil-return timing driven electromagnetic valve arranged in the oil return pipe; and an electronic control unit (ECU) connected to the oil-inlet timing driven electromagnetic valve and the oil-return timing driven electromagnetic valve, wherein the adjusting plunger chamber comprises an upper end including a first adjustable plug, and an adjusting spring mounted between the first adjustable plug and the adjusting plunger, and wherein the rotary plunger comprises an upper end including a plunger head, and a lower end including a gear engaged with a rack configured to rotate the rotary plunger.

2. The fully variable valve train according to claim 1, wherein the ECU is further connected to a pressure transducer arranged on the high-pressure oil rail, wherein an overflow port of the high-pressure oil rail is in fluid communication with the oil reservoir via an overflow pipe, wherein a high-pressure relief valve is arranged at the overflow port, and wherein a filter, a high-pressure oil injection pump, and an energy accumulator are arranged in the supply pipe.

3. The fully variable valve train according to claim 2, wherein a second adjustable plug is mounted at an upper end of the rotary plunger chamber.

4. The fully variable valve train according to claim 1, wherein a second adjustable plug is mounted at an upper end of the rotary plunger chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram illustrating a structure according to an example of the disclosure.

(2) FIG. 2 is a schematic diagram illustrating a structure of a fully variable valve train actuator according to an example of the disclosure.

DETAILED DESCRIPTION

(3) The disclosure will be described by way of example in more detail below with reference to the accompanying drawings.

(4) Referring to FIG. 1 and FIG. 2, a fully variable valve train according to an example of the disclosure includes an oil reservoir 1, a filter 2, a high-pressure oil injection pump 3, an energy accumulator 4, a high-pressure oil rail 5, a pressure transducer 6, a high-pressure relief valve 7, an electronic control unit 8, a rotation speed transducer 9, timing driven electromagnetic valves 10 and 11, a high-pressure oil return pipe adapter 12, a high-pressure oil inlet pipe adapter 13, a hydraulic cylinder 14, a plunger 15, a mounting base 16, a valve returning spring 17, and a valve 18. As shown in FIG. 2, a variable valve train actuator includes a mounting base 16, a fixing bolt 19, an O-shaped sealing ring 20, a hydraulic cylinder 14, a high-pressure oil return pipe adapter 12, a high-pressure oil inlet pipe adapter 13, a plunger 15, a second adjusting plug 21, a first adjusting plug 22, an adjusting spring 23, an adjusting plunger 24, a plug 25, and a rack 26.

(5) As shown in FIG. 1, when the valve train is not started, the plunger 15 is located at the top under the action of the valve returning spring 17. In this case, the timing driven electromagnetic valves 10 and 11 do not operate and wait for a pulse signal from the electronic control unit 8, and meanwhile, low-pressure oil is present in the plunger chamber. When the system starts running, the high-pressure oil injection pump 3 is driven by a motor to draw hydraulic oil from the oil reservoir 1, and impurities in the hydraulic oil are filtered out by the filter 2 therebetween, guaranteeing clean hydraulic oil entering the oil circuit. The energy accumulator 4 guarantees stable pressure of the hydraulic oil circuit and reduces fluctuation. Subsequently, high-pressure hydraulic oil flows into the high-pressure oil rail 5 on which the pressure transducer 6 for transmitting a pressure signal to the electronic control unit 8 in real time and the high-pressure relief valve 7 are mounted. When the oil pressure is excessively high, the relief valve 7 is opened to return the redundant hydraulic oil to the oil reservoir 1. The electronic control unit 8 controls opening and closing of two timing driven electromagnetic valves 10 and 11. When the timing driven electromagnetic valve 11 is opened, high-pressure oil enters the hydraulic cylinder 14, leading to increase of the pressure within the chamber. When the force applied to the plunger 15 by the hydraulic oil is larger than the force of the valve returning spring 17, the plunger 15 is pushed to move down, so that the valve 18 is opened. When the valve is required to return, the electromagnetic valve 11 connected to a high-pressure oil source is closed, while the timing driven electromagnetic valve 10 connected to a low-pressure oil source is opened. The valve 18 moves up under the action of the valve spring 17, pushing the plunger 15 to move up and thereby discharging the low-pressure oil out of the hydraulic cylinder, and then the plunger 15 and the valve 18 return to initial positions. Thus, one cycle is completed. In this process, the electronic control unit 8 receives a rotation speed signal from a crankshaft end and matches different orders of opening and closing timing electromagnetic valves with different rotation speeds to realize variable timing of the valve train.

(6) The structure diagram of the variable valve train actuator is designed according to the operating principle of the variable valve train, as shown in FIG. 2. With the hydraulic cylinder 14 as the major structure, the high-pressure hydraulic oil and the low-pressure hydraulic oil flow back and forth to push the plunger 15 to move, thus achieving the purpose of replacing the traditional cam plunger structure. Compared with a simple hydraulic cylinder, the actuator has a hydraulic buffer additionally, which is composed of four parts 22, 23, 24 and 25 as shown in the figure. When the plunger 15 moves down, the spring is compressed continuously, and with increasing compressive force, the plunger 15 moves down increasingly slower. As a result, the hydraulic oil below the plunger is squeezed out and moves into a pipe on the right. Nonetheless, with a dead zone below the plunger, a part of hydraulic oil cannot flow out and thus serves as a cushion. When the plunger moves to the dead zone of the hydraulic oil below, the plunger 15 is above and thus buffered by the oil cushion, so that the valve speed and impact can be significantly reduced. Moreover, a structure for rotating the plunger by means of an adjusting rack. When the lift needs to be adjusted, the rack 26 drives the plunger 15 to rotate so as to change the length of a part, in contact with an oil return hole, of the plunger 15, because the course of opening the intake valve depends on the length of the part, in contact with the oil return hole, of the plunger. The longer the contact part of the plunger, the longer the plunger stroke and the greater the valve lift. Rotation speed signals received by a transducer are matched with different lifts, thereby realizing instant lift adjustment.

(7) The rack 26 drives the plunger to rotate in the actuator, and the contact length of the plunger with the oil return hole is controlled by rotating the plunger. Different contact lengths may result in different movement lengths of the plunger, and the greater the contact length, the longer the movement distance of the plunger. Thus, the lift can be controlled by this method.

(8) The structure composed of the hydraulic cylinder 14, the first adjusting plug 22, the adjusting spring 23, the adjusting plunger 24, and the plug 25 allows a hydraulic dead zone to be formed in the valve at seating, leading to a low valve speed. Thus, the valve impact is greatly reduced as compared with other variable valve trains, and the vibration and noise of the engine due to the crash impact are reduced.

(9) The operating process of the fully variable valve train is as follows: the actuator is connected to the timing driven electromagnetic valves through oil pipes; when the system starts running, the motor actuates the high-pressure oil injection pump; when the timing driven electromagnetic valve connected to the oil inlet is opened, high-pressure oil enters the hydraulic cylinder, leading to increase of the pressure within the chamber; and when the force applied to the plunger by the hydraulic oil is larger than the force of the valve returning spring, the plunger is pushed to move down, so that the valve is opened. When the valve is required to be return, the timing driven electromagnetic valve connected to the oil inlet is closed, and the timing driven electromagnetic valve connected to the oil outlet is opened; the valve moves up under the action of the valve spring, pushing the plunger to move up and thereby discharging the low-pressure oil out of the hydraulic cylinder, and then the plunger and the valve returning spring to the initial positions. Thus, one cycle is completed. When the lift needs to be adjusted, the rack drives the plunger to rotate so as to change the length of the part, in contact with the oil return hole, of the plunger, that is, the course of opening the intake valve depends on the length of the part, in contact with the oil return hole, of the plunger. The longer the contact part of the plunger, the longer the plunger stroke and the greater the valve lift. The upper surface of the plunger is an inclined surface, and a sealing ring is arranged on the plunger to prevent oil leakage.