FI126002B

FI126002B - Valve actuator for gas exchange valves for internal combustion engine

Info

Publication number: FI126002B
Application number: FI20135265A
Authority: FI
Inventors: Rony Hollstein; Sebastian Brückel
Original assignee: Man Diesel & Turbo Se
Priority date: 2012-03-20
Filing date: 2013-03-19
Publication date: 2016-05-31
Also published as: CN103321700A; KR20130106783A; DE102012204396A1; CN103321700B; FI20135265A; JP6370530B2; KR101937492B1; JP2013194741A

Description

Valve drive for gas exchange valves on an internal combustion engine

The invention relates to a valve drive for gas exchange valves of an internal combustion engine according to the preamble of Claim 1.

Fig. 1 shows a detail from the valve drive 1 for gas exchange valves of an internal combustion engine known from DE 10 2004 057 438 A1 together with a cylinder head 2 of the internal combustion engine, which is preferentially embodied as a diesel engine. The valve drive 1 according to Fig. 1 comprises rocker arms 3, wherein each rocker arm 3 with a first end acts on at least one gas exchange valve which is not shown and with a second end is connected in an articulated manner with a push rod 4 each. Fig. 1 merely shows a rocker arm 3 and a push rod 4 of the valve drive 1. Each push rod 4 of the valve drive is brought into operational connection with an adjusting device for influencing the valve timing of the gas exchange valves, wherein the adjusting device for influencing the valve timing comprises an adjustable valve lever 7 for each push rod 4. Each of the valve levers 7 is coupled to an eccentric shaft 5, namely via an eccentric 6 coupled between the eccentric shaft 5 and the respective valve lever 7. Each of the valve levers 7 does not only act together with the eccentric shaft 5, but furthermore with a cam 9 which is positioned on a camshaft 10, namely via a roller 8 running on the respective cam 9. To influence the valve timing, the eccentric shaft 5 is rotatable in the sense of the double arrow 11 (see Fig. 2), wherein through the rotation of the eccentric shaft 5 a contact region of the roller 8 of the respective valve lever 7 on the respective cam 9 of the camshaft 10 changes in the sense of the double arrow 12 (see also Fig. 2). This causes a change of the valve timing of the gas exchange valves of the internal combustion engine.

In order to rotate the eccentric shaft with valve drives known from the prior art for influencing the valve timing of the gas exchange valves, a separate drive system is required with valve drives known from the prior art. This can be for example a separate electric of a separate hydraulic drive system. By way of such a separate drive system, a torque is applied to the eccentric shaft in the case of valve drives known from the prior art, in order to influence the valve timing of the gas exchange valves in this way.

Starting out from this, the present invention is based on the object of creating a new type of valve drive for gas exchange valves of an internal combustion engine which has a simpler construction.

This object is solved through a valve drive according to Claim 1. According to the invention, the adjusting device for influencing the valve timing is designed in such a manner that the eccentric shaft for influencing the valve timing is rotatable because of torques acting on said eccentric shaft during the operation.

With the present invention it is proposed for the first time not to provide an additional drive unit for rotating the eccentric shaft in a valve drive for gas exchange valves. It is rather proposed to rotate the eccentric shaft based on torques acting on said eccentric shaft during the operation.

Thus, during the operation, an operationally-induced torque on the eccentric shaft which is caused through the upward and downward movement of the rollers of the valve levers relative to the cams of the camshaft. According to the invention, this operationally-induced torque is utilised in order to rotate the eccentric shaft for influencing the valve timing. Because of this it is possible to omit a separate drive system for rotating the eccentric shaft. Because of this, the construction of the valve drive according to the invention is simplified relative to the valve drives known from the prior art.

According to an advantageous further development of the invention, the adjusting device for influencing the valve timing is designed as a hydraulic non-self-locking adjusting device, which when the latter permits a rotation of the eccentric shaft in a defined direction of rotation, blocks a rotation of the eccentric shaft in an opposite direction of rotation, so that the eccentric shaft can be rotated step-by-step or ratchet-like in the defined direction.

Because of this it is possible to specifically utilise the operationally-induced and alternately acting torque, which is brought about through the upward and downward movement of the valve lever on the cam of the camshaft for rotating the eccentric shaft for influencing the valve timing. To this end, the rotation of the eccentric shaft is exclusively permitted in a defined direction of rotation, whereas the rotation of the eccentric shaft in the opposite direction of rotation is blocked. Because of this, a step-by-step rotation of the eccentric shaft in the desired direction of rotation is permitted for influencing the valve timing of the gas exchange valves.

Accordingly, the rotation of the eccentric shaft for influencing the valve timing of the gas exchange valves is composed of a multiplicity of small individual rotations, wherein an opposite rotation in each case is prevented. Such a step-by-step rotation of the eccentric shaft corresponds to a ratchet-like rotation of the latter in the defined direction of rotation.

Preferentially, the adjusting device comprises a switching means, with the help of which the defined direction of rotation, in which the eccentric shaft can rotate, can be changed. By way of the switching means, the direction of rotation in which the eccentric shaft for influencing the valve timing of the gas exchange valves can rotate, can be defined and changed. It is likewise possible via the switching means to completely prevent a rotation of the eccentric shaft.

According to an advantageous further development of the invention, the adjusting device comprises a plurality of hydraulic chambers interacting with the eccentric shaft, wherein for releasing the rotation of the eccentric shaft in a first direction of rotation and for blocking the rotation of the eccentric shaft in an opposite second direction of rotation, hydraulic oil can flow out of a first hydraulic chamber and hydraulic oil can flow into a second hydraulic chamber, and wherein for releasing the rotation of the eccentric shaft in the second direction of rotation and for blocking the rotation of the eccentric shaft in the opposite first direction of rotation, hydraulic oil can flow out of a second hydraulic chamber and hydraulic oil can flow into a first hydraulic chamber. Preferentially, both hydraulic chambers are assigned at least one non-return valve, which prevents a return flow of the hydraulic oil from the hydraulic chamber, in which for the rotation of the eccentric shaft in the desired direction of rotation hydraulic oil is to flow, and which for the hydraulic chamber from which hydraulic oil is to drain, is bridged via a bypass line. The above embodiment of the adjusting device with the hydraulic chambers, nonreturn valves and bypass lines allows a simple design implementation of the valve drive according to the invention.

Preferred further developments of the invention are obtained from the subclaims and the following description. Exemplary embodiments of the invention are explained in more detail by means of the drawing without being restricted to this. Here it shows:

Fig. 1: a detail of a valve drive for gas exchange valves of an internal combustion engine known from the prior art;

Fig. 2: a detail of the valve drive of Fig. 1;

Fig. 3: a schematic diagram of details of a valve drive according to the invention;

Fig. 4: a schematic diagram of details of an alternative valve drive according to the invention;

Fig. 5: a schematic diagram of details of a further alternative valve drive according to the invention;

Fig. 6: a schematic diagram of details of a further alternative valve drive according to the invention; and

Fig. 7: a schematic diagram of design embodiment of a valve drive according to the invention.

The present invention relates to a valve drive for gas exchange valves of an internal combustion engine whose principal construction is shown in Fig. 1 and 2. Thus, the valve drive 1 comprises rocker arms 3, wherein each rocker arm 3 with a first end acts on at least one gas exchange valve and with a second end is connected in an articulated manner to a push rod 4 each. Each push rod 4 is brought into operational connection with an adjusting device for influencing the valve timing of the respective gas exchange valve. The adjusting device for influencing the valve timing comprises and adjustable valve lever 7 for each push rod 4, which on the one side acts together with an eccentric shaft 5 via an eccentric 6 and on the other side with a roller 8 running on a cam 9 of a camshaft 10. For influencing the valve timing, the eccentric shaft 5 is rotatable, as a result of which a contact region of the roller 8 of the respective valve lever 7 on the respective cam 9 of the camshaft 10 can be changed in order to change the valve timing of the gas exchange valves in this way.

According to the invention, the adjusting device for influencing the valve timing of the gas exchange valves is designed in such a manner that the eccentric shaft 5 for influencing the valve timing is rotatable because of torques packing on the eccentric shaft 5 during the operation. Accordingly, the valve drive according to the invention does not require a separate drive unit for rotating the eccentric shaft 5 for influencing the valve timing of the gas exchange valves, the valve drive according to the invention rather utilises operationally-induced torques, which act on the eccentric shaft 5 due to the upward and downward movement of the rollers 8 of the valve levers 7.

The rolling of the rollers 8 of the camshaft 10 brings about a horizontal force component in the direction of the eccentrics 6 interacting with the eccentric shaft 5, wherein this horizontal force component in the direction of the eccentric 6 because of the distance of the centre points of the eccentrics 6 to the centre point of the eccentric shaft 5 brings about a torque on the eccentric shaft 5. This operationally-induced torque is reciprocal, i.e. acts alternately in different directions and according to the invention is utilised for rotating the eccentric shaft 5 and thus for influencing the valve timing of the gas exchange valves.

Owing to the fact that a multiplicity of valve levers 7 roll on corresponding cams 9 of the camshaft 10 which are operationally connected to the eccentric shaft 5, a multiplicity of torque impulses on the eccentric shaft 5 are obtained per revolution of the camshaft 10. As already explained, these torque impulses are reciprocal, i.e. they act alternately in different directions.

The adjusting device for influencing the valve timing is preferentially designed as hydraulic non-self-locking adjusting device which, when the latter permits a rotation of the eccentric shaft 5 in a defined direction of rotation, blocks a rotation of the eccentric shaft 5 in the opposite direction of rotation, so that only those torque impulses are utilised for rotating the eccentric shaft 5, which bring about a rotation of the eccentric shaft 5 in the same defined direction of rotation at any time.

This causes a step-by-step rotation of the eccentric shaft 5 in the defined rotation of direction. By contrast, the rotation of the eccentric shaft 5 is not possible in the opposite direction of rotation, as a result of which a ratchet-like rotating of the eccentric shaft 5 in the defined direction of rotation is obtained.

In order to make possible a rotation of the eccentric shaft in different directions of rotation and thus change the valve timing of the gas exchange valves in different operational directions, the adjusting device comprises a switching means, with the help of which the defined direction of rotation, in which the eccentric shaft 5 can be rotated, can be changed. Preferentially, this switching means permits the rotation of the eccentric shaft in a first defined direction of rotation in a first switching position, wherein the rotation of the eccentric shaft in the second direction of rotation which is opposite with respect to the first defined direction of rotation is then blocked. In a second switching position of the switching means, the latter permits the rotation of the eccentric shaft in the second direction of rotation, wherein the rotation of the eccentric shaft of the first direction of rotation is then blocked. In a third switching position it is provided to block both directions of rotation of the eccentric shaft 5.

Fig. 3 shows a first variant of a possible implementation of the valve drive 1 according to the invention, wherein according to Fig. 3 the adjusting device for influencing the valve timing comprises a plurality of hydraulic chambers interacting with the eccentric shaft 5, namely a first hydraulic chamber 13 and a second hydraulic chamber 14. The two hydraulic chambers 13, 14 are each formed by a hydraulic cylinder 15, 16 in the variant of Fig. 3, wherein in the exemplary embodiment of Fig. 3 both hydraulic cylinders 15, 16 are coupled on the one hand among themselves via their piston rods 17 and on the other hand to the eccentric shaft 5 via a connecting rod 18 acting on the piston rods 17.

To release the rotation of the eccentric shaft 5 in a first direction of rotation, for example the direction of rotation visualised in Fig. 3 by the arrow 19 and for blocking the rotation of the eccentric shaft 5 in a second direction of rotation opposite thereto, hydraulic oil can flow out of a first hydraulic chamber, in Fig. 3 out of the hydraulic chamber 14 and hydraulic oil can flow into a second hydraulic chamber, in Fig. 3 into the hydraulic chamber 13. For this purpose, the two hydraulic chambers 13 and 14 are connected to storage tanks 20 and 21 for hydraulic oil.

By contrast, when a rotation of the eccentric shaft 5 is to take place in the second direction of rotation, i.e. in Fig. 3 opposite to the first direction of rotation 19, hydraulic oil can flow out of the second hydraulic chamber, i.e. in Fig. 3 out of the hydraulic chamber 13 and hydraulic oil can flow into the first hydraulic chamber, i.e. in Fig. 3 into the hydraulic chamber 14.

In order to prevent that hydraulic oil flows out of that hydraulic chamber 13 and 14 into which hydraulic oil is to flow for rotating the eccentric shaft 5 in the desired direction of rotation back into the respective storage tank 20 and 21, a non-return valve 24 and 25 each are connected in lines 22 and 23, via which the hydraulic chambers 13 and 14 are coupled to the respective storage tank 20 and 21 and via which hydraulic oil is to be delivered into the respective hydraulic chamber 13 and 14.

These lines 22, 23, in which the non-return valves 24, 25 are connected, are dependent on the switching position of switching means 26, 27 for that hydraulic chamber 13, 14, out of which hydraulic oil is to flow for rotating the eccentric shaft 5, is bridged via a bypass line 28, 29.

Thus, in Fig. 3, the bypass line 28, which interacts with the hydraulic chamber 13 and which is switched parallel to the line 22, is interrupted via the relevant switching means 26, so that in Fig. 3 hydraulic oil can flow into the hydraulic chamber 13 starting out from the storage tank 20, but no hydraulic oil can flow back into the storage tank 20 from the hydraulic chamber 13. The bypass line 29, which interacts with the other hydraulic chamber 14, by contrast, is opened via the relevant switching means 27, so that hydraulic oil can flow out of the hydraulic chamber 14 into the storage tank 21. Thus, the rotation of the eccentric shaft 5 in the direction of the arrow 19 of Fig. 3 is permitted and the opposite rotation is blocked. By changing the switching position of the switching means 26, 27, the permitted direction of rotation of the eccentric shaft 5 is reversible and the rotation of the latter completely blockable.

Accordingly, with the above configuration of the valve drive it is possible because of the reciprocal torque impulses acting on the eccentric shaft 5 during the operation to make possible dependent on the switching position of the switching means 26 and 27 the rotation of the eccentric shaft 5 in a defined direction of rotation, namely step-by-step or ratchet-like in a plurality of stages. The direction of rotation opposite with respect thereto however is blocked in each case.

Accordingly, for rotating the eccentric shaft 19 in a defined direction of rotation and accordingly to influence the valve timing of the gas exchange valves, a hydraulic chamber of a hydraulic cylinder in the variant of Fig. 3, in which both hydraulic chambers 13 and 14 are provided by separate hydraulic cylinders 15 and 16, is opened such that hydraulic oil can flow out of the latter, whereas hydraulic oil can flow into the hydraulic chamber of the other hydraulic cylinder. Depending on the switching position of the switching means 26 and 27, a step-by-step or gradual rotation of the eccentric shaft 5 in a defined direction of rotation is thereby possible, whereas the rotation movement of the eccentric shaft 5 in the opposite direction of rotation is blocked. Accordingly, by switching over the switching means 26 and 27 a direction of rotation reversal for the eccentric shaft 5 is possible.

An alternative implementation of the valve drive according to the invention is shown by Fig. 4, wherein in Fig. 4 both hydraulic chambers 13 and 14 are provided by a common hydraulic cylinder 30. The hydraulic cylinder 30, which in Fig. 4 provides both hydraulic chambers 13 and 14, is connected on the one side fixed to the housing and on the other side is coupled to the eccentric shaft 5 via the piston rod 17 and the connecting rod 18. The representation of the storage tanks for hydraulic oil, of the non-return valves and bypass lines has been omitted in Fig. 4 for the sake of clarity.

Further alternative configuration possibilities for the valve drive according to the invention are schematically shown by Fig. 5 and 6, wherein the hydraulic chambers 13 and 14 in turn for the sake of clarity are shown in Fig. 5 and 6 without the storage tanks for hydraulic oil, without the non-return valves and without the bypass lines.

In the variant of Fig. 5, the hydraulic chambers 13 and 14 are provided by a rotary vane piston, which comprises a stator 31 and a rotor 32, wherein the rotor 32 of the rotary vane piston schematically shown in Fig. 5 is arranged coaxially with respect to the eccentric shaft 5 and connected or coupled to the eccentric shaft 5.

In the variant of Fig. 6, the hydraulic chambers 13 and 14 in turn are provided by a common hydraulic cylinder 33, wherein between both hydraulic chambers 13 and 14 a thrust piston 34 extends. Thus, the thrust piston 34 is coupled to a toothing 36 of the eccentric shaft 5 via a toothing 35 in order to convert a linear displacement of the push rod 34 into a rotation of the eccentric shaft 5 for influencing the valve timing of the gas exchange valves.

As already explained, the hydraulic chambers 13 and 14 of the variants of Fig. 4 to 6 can be coupled in a manner similar to the variant of Fig. 3 via lines 22, 23 to non-return valves 24, 25 and via bypass lines 28, 29 to switching means 26, 27 to storage tanks 20, 21 for hydraulic oil. In contrast with the exemplary embodiment of Fig. 3, in which for each hydraulic chamber 13 and 14 a separate oil storage tank 20, 21 and a separate non-return valve 24, 25 are present, it is also possible for both hydraulic chambers to utilise a common oil supply and a common nonreturn valve. Such a variant is discussed in the following making reference to Fig. 7.

Thus, Fig. 7 in turn shows a variant of the invention, in which the two hydraulic chambers 13 and 14 are provided by separate hydraulic cylinders 15 and 16, the piston rods 17 of which are coupled to the eccentric shaft 5 via a coupling rod 18. With respect to these details, the variant of the Fig. 7 corresponds to the variant of Fig. 3.

In contrast with the variant of Fig. 3, however, both hydraulic chambers 13, 14 and thus both hydraulic cylinders 15, 16 are assigned a common non-return valve 37 in the variant of Fig. 7, which is connected in a line 38, via which the hydraulic chambers 13 and 14 starting out from an engine lubricating oil system can be filled with hydraulic oil. Viewed in flow direction of the hydraulic oil downstream of the non-return valve 37, this line 38 splits into two part lines 38a and 38b, which are opened or blocked like bypass lines 40 and 41, depending on the switching position of a common switching means 39.

The common switching means 39 in Fig. 7 is a valve rod, which can be linearly displaced by a valve control solenoid 42, wherein in the switching position of Fig. 7 with respect to the hydraulic chamber 13, the part line 38a is opened and the bypass line 40 is blocked, whereas with respect to the hydraulic chamber 14, the part line 38b is blocked and the bypass line 41 is opened, so that in the switching position in Fig. 7 hydraulic oil can flow into the hydraulic chamber 13 and out of the hydraulic chamber 14.

Through corresponding linear displacement of the valve rod 39, it is possible, for reversing the direction of rotation for the eccentric shaft 5, with respect to the hydraulic chamber 13, to block the part line 38a and open the bypass line 40 and with respect to the hydraulic chamber 14, open the part line 38b and block the bypass line 41.

Accordingly, depending on the switching position of the valve rod 39, the eccentric shaft 5 can be displaced in different directions of rotations in order to thereby influence the valve timing of the gas exchange valves, wherein the rotation of the eccentric shaft 5 in both possible directions of rotation is limited by stops 43.

To improve the dynamics of movement of the eccentric shaft 5 during the rotation of the latter, the bypass lines 40 and 41 are assigned drainage orifices 44 in Fig. 7, via which hydraulic oil can flow out of the respective hydraulic chambers 13, 14. Likewise, to improve the dynamics of movement of the eccentric shaft 5 in the region of the stops 43, damping via end position dampers which are not shown can take place.

List of reference numbers 1 Valve drive 2 Cylinder head 3 Rocker arm 4 Push rod 5 Eccentric shaft 6 Eccentric 7 Valve lever 8 Roller 9 Cam 10 Camshaft 11 Rotation of the eccentric shaft 12 Displacement of the roller 13 Hydraulic chamber 14 Hydraulic chamber 15 Hydraulic cylinder 16 Hydraulic cylinder 17 Piston rods 18 Connecting rod 19 Rotation of the eccentric shaft 20 Storage tank 21 Storage tank 22 Line 23 Line 24 Non-return valve 25 Non-return valve 26 Switching means 27 Switching means 28 Bypass line 29 Bypass line 30 Hydraulic cylinder 31 Stator 32 Rotor 33 Hydraulic cylinder 34 Push rod 35 Toothing 36 Toothing 37 Non-return valve 38 Line 38a Part line 38b Part line 39 Valve rod 40 Bypass line 41 Bypass line 42 Valve control solenoid 43 Stop 44 Drainage orifice

Claims

A valve actuator for gas exchange valves of an internal combustion engine, wherein the actuator is provided with rocking levers (3), wherein each rocking lever (3) acts on the gas exchange valve at the first end and is connected to the push rod (4) wherein the adjusting device for actuating the valve control times has an adjustable rocker lever for each push rod (4) which cooperates with the eccentric axis (5) on the one hand and the roll (8) on the cam (9) on the cam shaft (10) ) is rotatable and thus the contact area of the respective roller (8) of the respective rocker arm (7) with the respective cam (9) of the camshaft (10) is variable, characterized in that the adjusting device for to influence the valve control times, it is rotatable based on the torques affecting this application.

Valve actuator according to claim 1, characterized in that the actuator for effecting the valve control times is designed as a hydraulic, non-limiting actuator which, when this allows rotation of the eccentric shaft (5) in a certain rotation, prevents rotation of the eccentric shaft (5). such that the eccentric shaft (5) is rotatable in a certain direction in a stepwise or ratchet manner.

Valve actuator according to Claim 2, characterized in that the adjusting device comprises at least one coupling means (26, 27, 39) for changing the direction of rotation in which the eccentric shaft (5) can be rotated.

Valve actuator according to Claim 2 or 3, characterized in that the adjusting device has a plurality of hydraulic chambers acting in conjunction with the eccentric shaft (5), to release rotation of the eccentric shaft (5) in a first rotation and prevent the hydraulic fluid may flow out and the hydraulic fluid chamber (13) may flow the hydraulic oil in, and wherein, to release rotation of the eccentric shaft (5) to the second rotation and to prevent rotation of the eccentric shaft (5), the hydraulic fluid 13 Hydraulic oil can be infused into the mouth (14).

Valve drive according to Claim 4, characterized in that at least one non-return valve (24, 25, 26) is provided in each of the hydraulic chambers (13, 14) which prevents the hydraulic oil from returning from the hydraulic chambers (13, 14) into which the hydraulic oil is to flow. is bypassed by a bypass line (28, 29, 40, 41) for a hydraulic chamber (13, 14) from which the hydraulic oil must flow out.

Valve actuator according to Claim 4 or 5, characterized in that both hydraulic chambers (13, 14) are formed by a common hydraulic cylinder (30) which is fixed on one hand and connected to an eccentric shaft (5) on the other hand.

Valve actuator according to Claim 4 or 5, characterized in that both hydraulic chambers (13, 14) are formed by a rotary piston, the rotor of which is coaxially connected to the eccentric shaft (5).

Valve actuator according to Claim 4 or 5, characterized in that the two hydraulic chambers (13, 14) are formed by a common hydraulic cylinder (33) comprising a percussion piston (34) disposed therebetween which is engaged by a cam (5) on an eccentric shaft (5). ) for teeth (36).

Valve actuator according to Claim 4 or 5, characterized in that the first hydraulic chamber (14) is formed by a first hydraulic cylinder (16) and a second hydraulic chamber (13) is formed by a second hydraulic cylinder (15) connected to each other and to the eccentric shaft (5) .

Valve actuator according to one of Claims 4 to 9, characterized in that both hydraulic chambers (13, 14) are provided with a common non-return valve (37) or in each case a non-return valve (24, 25) which is connected to the conduit (38, 22, 23). ) through which the hydraulic chambers (13, 14) can be filled with hydraulic oil from the engine lubricating oil system.

Valve actuator according to one of Claims 4 to 10, characterized in that an outlet choke (44) is provided in the bypass line (28, 29, 40, 41) through which the hydraulic chamber (13, 14) can be emptied.

Valve drive according to one of Claims 1 to 11, characterized in that the rotation of the eccentric shaft (5) is limited by the stops (43).

Valve drive according to Claim 12, characterized in that the rotation of the eccentric shaft (5) is damped in the region of the stops (43) by means of end position dampers.