EP0582846B1 - Internal combustion piston engine with gas exchange valves per cylinder - Google Patents

Description

The invention relates to a reciprocating piston internal combustion engine with at least two gas exchange valves per cylinder, which act in particular in parallel and are actuated by cams which are adjustable relative to one another and whose camshafts are arranged concentrically to one another, the phase angle (spread) between all in particular in addition to the phase angle between the cams parallel acting cams and the crankshaft interacting with the reciprocating piston can be changed.

The gas exchange valves can be the intake valves and / or exhaust valves of an internal combustion engine cylinder. A camshaft, in which, for example, the two cams of two cylinder inlet valves, which act, so to speak, in parallel, can be rotated relative to one another, is known from WO 91/10047. With the help of this so-called cam phasing, in which the phase angle between the two cams can thus be changed, the gas exchange dynamics of a reciprocating piston internal combustion engine can be influenced in a variety of ways. So if there is a certain phase angle the The entire valve opening duration is prolonged, and at the same time, such a phase angle produces the effect that one of the gas exchange valves acting in parallel opens in front of the other, so that a desired inflow swirl can be generated in the combustion chamber in the case of inlet valves acting in parallel. The already mentioned change in the total opening time, on the other hand, is particularly noticeable in the case of exhaust valves acting in parallel, since this allows effective residual gas control due to the so-called valve overlap, ie the time overlap when the intake valves open. In order to achieve low pollutant emissions, it may be desirable, in the sense of internal exhaust gas recirculation, to leave portions of the burnt residual gas from the previous combustion stroke of different sizes, depending on the operating point, during the following combustion stroke in the combustion chamber.

From FR-A-1 109 719, from which the present invention is essentially based, a valve actuation device is known in which, in addition to the phase angle between two cams assigned to an internal combustion engine cylinder, the phase position, ie the so-called spread, between all cams and the crankshaft interacting with the reciprocating piston can be changed. In this known prior art, the two cams assigned to a cylinder act either on an intake valve and an exhaust valve or on a single lift valve. However, this known device can also be used not only to adjust the phase angle, for example between a first and a second intake cam or exhaust cam of the internal combustion engine, but also the phase position of the first cam and the second cam with respect to the movement sequence of the reciprocating piston or with respect to the one with it to change the coupled angle of rotation of the engine crankshaft. This combination of both the change in the phase position of all gas exchange valves and the change in phase angle between all gas exchange valves per cylinder offers unimagined possibilities for further optimizing the gas exchange dynamics of this cylinder.

In the known device according to FR-A-1 109 790, both the phase position and the phase angle would be varied with the aid of a single actuator. As a result, not only the required construction effort but also the required control logic can be kept low. In connection with gas exchange valves acting in parallel, it was recognized that, in order to achieve good results, it may be sufficient if, starting from a small spread and an extremely small phase angle with increasing spread, i.e. increasing phase position between the cams and the crankshaft, the phase angle between the parallel acting cams is enlarged. In this case, in the full-load operation of the internal combustion engine and in a region close to full load, a slight spread and a phase angle of the amount 0 are preferably set. With decreasing internal combustion engine load, ie towards the partial load range, the spread can be increased and at the same time an ever increasing phase angle can be set between the cams acting in parallel. In the case of two gas exchange valves acting in parallel, this means nothing other than that the spread of, for example, the second gas exchange valve is increased even further than that of the first gas exchange valve. These measures thus result in optimal filling with early intake valve closing and, desirably, low in full-load operation and in the area close to full load Residual gas content. Towards the part-load range, on the other hand, the charge movement is increased, since the phasing between the cams acting in parallel is set and, moreover, by increasing the spread, the valve opening times in the case of the intake valves are better adapted to the reduced gas exchange dynamics in the intake system of the internal combustion engine. If the measures mentioned are applied to the exhaust valves of the internal combustion engine, a desirably larger valve overlap with the intake valves can be set in the partial load range in order to leave a higher residual gas content in the cylinder.

Although useful results could be achieved with the previously described valve actuation device, improvements which the present invention has set out to demonstrate are desirable.
To solve this problem, the characterizing features of claims 1 or 5 are provided. Advantageous training and further education are included in the subclaims.

For individual adjustment of the in particular two cams or camshafts relative to a crankshaft interacting with the reciprocating piston, in particular two adjusting bolts which can be displaced in the longitudinal direction of the shaft and which are arranged concentrically to one another can be provided, which are connected via helical gears on the one hand to the assigned camshaft and on the other hand to a camshaft drive wheel. Accordingly, an individual is provided Adjustment of the two camshafts each by means of its own adjusting bolt, the two adjusting bolts being arranged concentrically to one another in order to achieve an advantageous and compact design, analogously to the camshafts. The adjusting bolts are provided on their outer sides with helical gears and cooperate with the camshafts on which one of the cams is arranged in such a way that the helical gearing of the respective adjusting bolt meshes with corresponding helical gearing of the camshafts and / or their drive wheels, so that the respective adjusting bolt , if it is displaced in the longitudinal direction of the respective camshaft, this is rotated about its longitudinal axis by this displacement movement.

The adjusting bolts can or can be moved hydraulically, ie the adjusting bolts carry pistons which are arranged in a hydraulic cylinder or a hydraulic chamber. Appropriate exposure to a hydraulic medium allows these pistons and thus also the adjusting bolts to be moved in the longitudinal direction. It is advisable to arrange the pistons of all adjusting bolts - in a preferred embodiment, two camshafts arranged concentrically to one another and thus also two adjusting bolts arranged concentrically to one another - in a common hydraulic chamber. These pistons divide the hydraulic chamber into several hydraulic rooms connected in series, in the case of two pistons there are three hydraulic rooms connected in series. By appropriately loading these hydraulic spaces with differently high pressure levels, different pressure ratios can thus be generated in the individual hydraulic spaces, as a result of which one or both adjusting bolts can be moved as desired. For this purpose, individual valves can be assigned to the hydraulic rooms, which establish a desired connection with a hydraulic system or interrupt, the hydraulic system preferably offering two different pressure levels.

A particularly compact design results again when the hydraulic chamber is integrated in the camshaft drive wheel. Then the camshaft drive wheel is also arranged concentrically with the preferably two camshafts and in particular the two adjusting bolts. It is advisable to provide longitudinal teeth between the adjusting bolts or the pistons attached to them and the camshaft drive wheel, which at the same time forms the chamber wall of the hydraulic chamber, in order to enable the displacement movement and to transmit the rotary movement of the camshaft in a simple manner. Ensure the drive wheel on the adjusting bolts and from there on the camshafts.

According to another embodiment (claims 5 and following) it can be provided that for adjusting the two camshafts in relation to a crankshaft interacting with the reciprocating piston, two adjusting bolts which can be displaced in the longitudinal direction of the shaft and are arranged concentrically to one another are provided, the first adjusting bolt with the first camshaft and with one camshaft -Drive wheel each via a toothing, of which at least one is designed as a helical toothing, and wherein the second adjusting bolt with the second camshaft and the first adjusting bolt are each connected via a toothing, one of which is designed as a helical toothing and one as a straight toothing and a means preventing relative movement between the adjusting bolts is provided depending on the boundary conditions. With regard to a particularly simple construction, an adjusting device with these features uses an optimally recognized relationship between the so-called spread, ie the phase position of the gas exchange valves with respect to the crankshaft and the so-called phase angle, ie the angle between the first and the second gas exchange valve or cam. It was recognized that in a higher load range of the internal combustion engine, depending on the internal combustion engine speed, a different spread of the gas exchange valves should be set, but that there are no phasing between these gas exchange valves or intake valves, as there are two intake valves operating in parallel should, ie the phase angle between the two intake valves per cylinder should be of the amount 0. On the other hand, the phasing, ie the phase angle between the two intake valves per cylinder, should be increased starting from an approximately medium load when the internal combustion engine load decreases and at constant speed.

Applying this knowledge, the adjustment of the two cams or camshafts again takes place by means of an adjusting bolt, whereby, analogously to the camshafts, the two adjusting bolts are also arranged at least partially concentrically to one another in order to achieve an advantageous and compact design. The adjusting bolts are provided on their outer sides with helical gears and cooperate with a camshaft or a camshaft drive wheel in such a way that the respective adjusting bolt, when it is displaced in the longitudinal direction of the respective camshaft, rotates it about its longitudinal axis by this displacement movement.

The adjusting pin assigned to the second camshaft can be moved by the first adjusting pin. For this purpose, the second adjusting bolt is connected to the first adjusting bolt so as to be displaceable in the longitudinal direction of the shaft by means of straight toothing also extending in the longitudinal direction of the shaft. The second adjusting bolt is over a helical toothing connected to the second camshaft (of course, the attachment of the spur gear and helical gear can also be reversed). If the first adjusting bolt is now shifted in the longitudinal direction of the shaft, the second adjusting bolt is not necessarily moved in the longitudinal direction of the shaft due to the different frictional forces in the helical toothing or spur toothing. Thus, when the first adjusting bolt is shifted, the phase angle between the first and the second camshaft remains constant, since then, viewed in the longitudinal direction of the shaft, a relative movement between the first and second adjusting bolts can take place, so that the helical toothing of the second adjusting bolt remains ineffective. If, on the other hand, a relative movement between the first and the second adjusting pin is prevented by an initially still generally mentioned means, the second adjusting pin is then simultaneously displaced when the first adjusting pin is moved, so that due to the helical teeth provided between this second adjusting pin and the second camshaft second camshaft is additionally rotated. The phasing or the phase angle between the second and the first camshaft is changed in this way.

As indicated, this generally-mentioned means blocks or allows a relative movement between the first and the second adjusting bolt depending on certain boundary conditions. As explained above, this boundary condition can be, for example, the load, ie the current load point of the internal combustion engine. Depending on the load of the internal combustion engine, this means can thus be activated or deactivated, for example via a hydraulic system. Another possible boundary condition is, however, the value of the spread, for example of the first camshaft, ie the current position of the first adjusting bolt. For example be it possible to move this first adjusting bolt slightly in the longitudinal direction of the shaft from a rest position without the second adjusting bolt being carried along. After a certain displacement path, on the other hand, a stop of the second adjusting bolt hits a corresponding stop of the first adjusting bolt. Now, with a further displacement movement of the first adjusting bolt, the second adjusting bolt is also taken along.

Instead of a stop or next to one, the means preventing the relative movement between the adjusting bolts can also be designed as a lockable or releasable clamping body. A clamp body known per se can be actuated via a hydraulic system, which can be easily guided in a known manner to this clamp body arranged in the camshaft. In a similar way, for example, a hydraulic system can actuate a propelling means for the second adjusting bolt, this propelling means then being piston-like and, with suitable control, can also take over the function of the means preventing a relative movement between the two adjusting bolts.

Two stops between the two adjusting bolts, which are effective in opposite directions of movement and allow a certain relative movement between them, make it easy to implement the above-described relationship between optimal spreading and optimal phasing depending on certain boundary conditions. The first stop can be designed as a direct stop, ie the mutually facing end faces of the first and of the second adjusting bolt come into contact with one another. The second stop, on the other hand, can be inserted into the end face of the second adjusting bolt, with a web of the first Adjusting pin cooperating pin is formed, which is provided with a head and is thus designed like a head screw, the head of the pin forming the actual stop surface with the web of the first adjusting pin. An example of a clamping body as the means preventing relative movement between the adjusting bolts, however, is at least one mandrel mounted in one of the adjusting bolts, which can engage in a corresponding recess in or on the other adjusting bolt. This mandrel can be moved, for example, using the hydraulic system already mentioned above and / or using a spring element.

Preferred exemplary embodiments which show these and further advantageous features which may be essential to the invention are described in more detail below. 1a, 1b show valve lift curves to explain the terms of the phase angle or the phase position / spread, while in FIG. 2 a basic internal combustion engine operating map is shown with individual areas, for each of which a different phasing setting is optimal. 3a, 3b show an embodiment similar to the known prior art. FIG. 4 shows an embodiment according to claim 1 of the invention and FIGS. 5, 6 show another form according to claim 5. In each case, a camshaft designed according to the invention, including the adjusting bolts that cause the phase angle or phase position change, is shown in schematic diagrams.

1a, 1b, three valve lift curves 1, 2, 3 of three gas exchange valves of an internal combustion engine cylinder are shown. The valve lift curves 1, 2 represent the valve lift profiles of two parallel-acting cylinder inlet valves over the time axis, while the valve lift curve 3 shows the stroke course of a cylinder exhaust valve. LW-OT describes the point in time at which the piston is at its top dead center during the gas exchange phase. The phase position of, for example, the first inlet valve with the elevation curve 1 is characterized by the distance s, which is usually also referred to as the spread. The letter p denotes the phase angle which exists between the inlet valves acting in parallel or their elevation curves 1, 2 of a cylinder. Of course, this phase angle p is also represented as a distance analogous to the spread s over the time axis.

Fig. 1a shows the conditions at full load operation of the internal combustion engine. Here, the phase position or spread s is small, as is the phase angle p. In a preferred embodiment, the latter even takes the amount 0. According to the invention, the phase position / spread s and the phase angle p are increased in partial load operation, which is shown in FIG. 1b. With these measures, as described above, the charge change of the internal combustion engine can be optimally coordinated with regard to the different operating states or operating points.

Fig. 2 shows a schematic diagram of an operating map of an internal combustion engine. The torque M output by the internal combustion engine is plotted against the engine speed n. The upper limit line VL represents full-load operation. Below this full-load line VL there is the upper part-load range designated I, below this is the middle part-load range II and again below this the lower part-load range III. According to the above explanations, the phase angle can be = 0 at full load (VL), ie the two valve lift curves 1, 2 should lie congruently one above the other. In the upper part-load range I, a phase angle increasing with decreasing load, ie towards the part-load range II, is to be generated. A relatively small, constant phase angle should be maintained in the middle part-load region II, while a continuously increasing phase angle, ie a continuously increasing phasing, is desired in the lower part-load region III. In addition, the spread is changed, for example, starting from the full-load line VL with decreasing internal combustion engine load, ie towards the lower part-load range III. As the load decreases, the phase position, ie the position of the first cam or the first camshaft (valve lift curve I) with respect to the crankshaft, is changed, the phase position of the second cam / the second camshaft also to undergo such a change, but already increased by that Phasing explained.

3a shows a longitudinal section through a camshaft for two gas exchange valves acting in parallel per internal combustion engine cylinder with an actuator provided on the end face for changing the phase position and phase angle of the cams according to the invention. A first cam for a first gas exchange or inlet valve is denoted by 11, a second cam for actuating a gas exchange valve of this cylinder acting in parallel bears the reference number 12. There is also a further first cam 11 'and a further second cam 12' of another Internal combustion engine cylinders.

The first cams 11, 11 'are fastened on a first camshaft 10 which, as can be seen, is composed of an end part 10a and a shaft part 10b which are rigidly connected to one another. The second cam 12, 12 '- as the cross section according to FIG. 3b shows through the camshaft - are fastened to the second camshaft 20 by means of a bolt 21. The first camshaft 10 is hollow-cylindrical and can therefore accommodate the second camshaft 20 designed as a solid shaft, ie the two camshafts 10, 20 are arranged concentrically with one another. In the area of the cams 12 or the bolts 21, segment-shaped recesses 13 are provided in the outer first camshaft 10 in order to allow the bolt 21 to pass even when the inner second camshaft 20 is rotated relative to the outer, first camshaft 10 about the common shaft longitudinal axis 14 .

A camshaft drive wheel 15 is mounted partially within the cup-shaped widening free end of the end part 10a of the first camshaft 10. This drive wheel 15 can be rotated relative to the front part 10a about the shaft axis 14 by a certain angular amount. Thus, the screw connection designated by reference numeral 16 is merely an axial securing device, which is designed like an elongated hole and allows the drive wheel 15, which is provided with chain teeth 15 ′ on its circumference, to rotate relative to the first camshaft 10.

An adjusting bolt 30 is arranged concentrically within the hollow cylindrical drive wheel 15. This adjusting bolt 30 extends into a recess 22 of the second camshaft 20. The wall of this recess 22, which begins at the end face of the second camshaft 20 and extends in the direction of the shaft longitudinal axis 14, has helical teeth in some areas (reference number 23). A helical toothing 32 of the same pitch is located on the portion of the adjusting bolt 30 which projects into the recess 22.

A longitudinally toothed section 33 adjoins this second helically toothed section 32 of the adjusting bolt 30. With this longitudinally toothed section 33, the adjusting bolt 30 lies in the interior of the end part 10a of the camshaft 10. The longitudinal toothing 33 of the adjusting bolt 30 interacts with a longitudinal toothing 17 which emerges from the wall of the first camshaft 10, which is necessarily hollow in this area, or from the Inner wall of the front part 10a is worked out.

The longitudinally toothed section 33 of the adjusting bolt 30 is followed by a first helical section 31 which lies within the camshaft drive wheel 15, which is also provided with a helical toothing 18.

If the adjusting bolt 30 is thus moved in a manner not shown in the direction of arrow 4, this causes rotation of the adjusting bolt 30 due to the pairing of the helical gears 31/18 compared to a stationary drive wheel 15, which is caused by the pairing of the longitudinal gears 33/17 first camshaft 10 is transmitted in a ratio of 1: 1 and thus, for example, increases the spread s. Because of the second pair of helical gears 32/23, the second camshaft 20 is simultaneously rotated relative to the drive wheel 15, so that - as desired and explained in connection with FIGS. 1a, 1b - the phase angle p between the second cam 12 and the first Cam 11 is enlarged.

By adjusting the pitch of the individual helical gears or helical gear pairing 18/31 or 23/32, it can thus be determined to what extent the adjusting bolt 30 is shifted in accordance with Arrow direction 4 changes the phase position / spread s together with the phase angle p. As mentioned at the outset, the dynamics of the charge change of a combustion engine equipped with a camshaft according to the invention including an actuator or adjusting bolt 30 can be optimally designed to meet the respective requirements. Furthermore, there is an optimal power flow, since a pair of longitudinal teeth 17/33 is provided between the outer first camshaft 10 and the adjusting bolt 30. Furthermore, the durability of the second camshaft 20 in connection with its cams 12, 12 'is increased in that this second camshaft 20 is designed as a solid shaft. A large number of modifications of this first exemplary embodiment are possible. For example, the first cam 11 can actuate an inlet valve and the second cam 12 can actuate an outlet valve. With this, too, an improved charge change can be achieved for both cams by simultaneously changing the phase position and phase angle.

Fig. 4 shows an embodiment of the invention is also shown a longitudinal section through a camshaft for two gas exchange valves acting in parallel per internal combustion engine cylinder with adjusting bolts provided on the end face for changing the phase position and phase angle of the cams, the same reference numerals designating the same components as in the first embodiment.

Concentrically within the hollow-cylindrical first camshaft 10, in addition to the second camshaft 20, there is in turn a likewise hollow-cylindrical first adjusting bolt 30. This first adjusting bolt 30 is connected to the first camshaft 10 via a helical toothing 31. A second adjusting bolt 40 is provided concentrically within the first adjusting bolt 30 and extends into a recess 22 in the second Camshaft 20 extends into it. The wall of this recess 22, which begins at the end face of the second camshaft 20 and extends in the direction of the shaft longitudinal axis 14, is partially helically toothed. A helical toothing 23 of the same pitch is located on the portion of the adjusting bolt 40 which projects into the recess 22.

The two adjusting bolts 30, 40 protrude into a hydraulic chamber 50 and each carry a piston 51, 52 at their end, which together with the hydraulic chamber 50 each form a cylinder-piston unit. These pistons 51, 52 are connected to the wall of the hydraulic chamber 50 each via a longitudinal toothing 17, so that with respect to this hydraulic chamber 50, the two pistons 51, 52 and the two adjusting bolts 30, 40 can be displaced in the direction of the longitudinal axis 14 of the camshaft, whereby a torque about this longitudinal axis of the shaft can be transmitted simultaneously from the hydraulic chamber 50 to the two adjusting bolts 30, 40. The outer wall of the hydraulic chamber 50 is therefore provided with a camshaft drive wheel 15, so that the hydraulic chamber 50 is virtually integrated into the camshaft drive wheel. Thus, if the camshaft drive wheel 15 rotates about the shaft longitudinal axis 14 common to the two camshafts 10, 20 and the two adjusting bolts 30, 40, the two adjusting bolts 30, 40 become via the longitudinal toothing 17 and the two camshafts 10 via the helical gears 31 and 23 , 20 entrained, so that, as desired, the cams 11, 12 are set in a rotary movement about the longitudinal axis 14.

In addition, the first adjusting bolt 30 can be moved in the direction of the longitudinal axis 14. Due to the helical toothing 31, this displacement movement causes a relative rotary movement of the first camshaft 10, as a result of which the above-mentioned spread s of the associated one Valve lift curve 1 is changed. If the second adjusting pin 40 is displaced in the direction of the shaft longitudinal axis 14, this causes the second camshaft 20 to twist due to the helical teeth 23. As a result, the phase angle p between the valve lift curve 2 of the second cam 12 and the valve lift curve 1 of the first cam 11 is changed. As mentioned at the beginning, the gas exchange dynamics of an internal combustion engine equipped with a camshaft including adjusting bolts according to the invention can be optimally configured to the respective requirements by specifically adapting the spread and the phase angle.

The two adjusting bolts 30, 40 can be displaced in the direction of the shaft longitudinal axis 14 by correspondingly applying hydraulic pressure to the pistons 51, 52 attached to them. As already explained, the pistons 51, 52 are guided in a hydraulic chamber 50 and divide this hydraulic chamber into three hydraulic chambers 53, 54, 55 connected in series. Each of these hydraulic chambers 53 to 55 can be connected via an individual valve 56 to a hydraulic system, not shown, that different pressure ratios can be set in the individual hydraulic chambers in order to effect a displacement movement of one or the other or both pistons 51, 52 or adjusting bolts 30, 40 via these different pressure ratios.

If the first hydraulic chamber 53 is closed and the pressure in the second hydraulic chamber 54 is increased while at the same time the pressure in the third hydraulic chamber 55 is reduced, this causes the second adjusting bolt 40 to shift to the left. In this way, for example, the phase angle between the valve lift curve 2 of the second cam 12 and the valve lift curve 1 of the first cam 11 is increased. However, if the pressure in the Hydraulic chamber 55 increases, while at the same time the pressure in hydraulic chamber 54 is reduced, the second adjusting pin 40 is shifted to the right, which causes the second camshaft 20 to rotate in the opposite direction and thus causes a reduction in the phase angle p.

If the pressure in the second hydraulic chamber 54 is increased and reduced in the first hydraulic chamber 53 at a constant pressure in the hydraulic chamber 55 - then the associated individual valve 56 is closed - this displaces the first adjusting bolt 30 in the direction of the shaft longitudinal axis 14 to the right and thus rotates the first one Camshaft 10, for example, in such a way that the spread s of the first valve lift curve 1 is increased. Conversely, if the pressure in the hydraulic chamber 53 is increased and the pressure in the hydraulic chamber 54 is reduced, the spread s is then reduced by shifting the first adjusting bolt 56 to the left. Of course, it is also possible to change the pressure conditions in all three hydraulic spaces 53, 54, 55 simultaneously and thus to achieve a variation in the spread s and the phase angle p at the same time.

As further exemplary embodiments of the invention, FIGS. 5, 6 each show a longitudinal section through a camshaft for two gas exchange valves acting in parallel per internal combustion engine cylinder with adjusting bolts provided on the end face for changing the phase position and phase angle of the cams. Again, the same components with the same reference numerals as in FIGS. 3, 4 are designated.

A fixed component of the first camshaft 10 is here again the front part 10a, which is only partially shown and is placed on the front end. Is concentric within this hollow cylindrical end portion 10a an adjusting pin 30 which is also of essentially hollow cylindrical configuration is arranged. This first adjusting bolt 30 is connected to the front part 10a and thus also to the first camshaft 10 via a straight toothing 17 oriented in the direction of the longitudinal axis 14 of the shaft, so that it is possible to set this adjusting bolt 30 in or against the direction of arrow 4 with respect to the end part 10a or to shift the camshaft 10. Similar to the connection with the front part 10a, the first adjusting bolt 30 is connected at its left-hand end, not shown, to a camshaft drive wheel, with a helical toothing being provided in the area of this connection instead of the straight toothing. The camshaft drive wheel, not shown, is driven in a known manner, for example via a chain drive, by the crankshaft of the internal combustion engine. The camshaft 10 can thus be set into a rotary movement about the shaft longitudinal axis 14 via the camshaft drive wheel (not shown) and the first adjusting bolt 30. If the adjusting bolt 30 is additionally displaced in or against the direction of the arrow 4, the helical toothing between the adjusting bolt 30 and the camshaft drive wheel results in an additional rotation of the camshaft 10 relative to the camshaft drive wheel. This adjustment mechanism is quite common in today's camshaft adjustment systems and is therefore familiar to the person skilled in the art and, as is also known, serves to change the spread, ie the phase position of the cams in relation to the crankshaft.

The first adjusting bolt 30 has a central recess 34 into which a second adjusting bolt 40 is inserted. This second adjusting bolt 40 can also be displaced with respect to the first adjusting bolt 30 in or against the direction of the arrow 4, these two adjusting bolts 30, 40 being connected to one another via straight teeth 33 are, so that the first adjusting pin 30 takes the second adjusting pin 40 when rotating about the longitudinal axis 14.

With its end opposite the first adjusting pin 30, the second adjusting pin 40 projects into a central recess 22 in the second camshaft 20. Connected in such a way that when the second adjusting bolt 40 rotates about the shaft longitudinal axis 14, the second camshaft 20 is also rotated about this shaft longitudinal axis 14, the camshaft 20 is connected to the adjusting bolt 40 via a helical toothing 23. This helical toothing 23 causes an additional longitudinal displacement of the adjusting bolt 40 in or against the arrow direction 4, the camshaft 20 is rotated by an additional amount compared to the adjusting bolt 40.

The following functional relationship thus results with the components explained so far:
A camshaft drive wheel, not shown, rotates both the first adjusting bolt 30 and the second adjusting bolt 40 about the shaft longitudinal axis 14, these two adjusting bolts 30, 40 each taking the camshafts 10, 20 assigned to them with them. Thus, first of all, the two camshafts 10, 20 rotate around the longitudinal axis 14 analogously to the camshaft drive wheel, not shown.
If, in addition, only the first adjusting bolt 30 is moved in or against the direction of the arrow 4, this leads to an additional rotation of the first adjusting bolt 30 with respect to the camshaft drive wheel due to the helical toothing described between this first adjusting bolt 30 and the camshaft drive wheel, not shown. This means that likewise the first camshaft 10 and, due to the transmission via the second adjusting pin 40, also the second camshaft 20 around it additional dimension compared to the camshaft drive wheel. The two camshafts 10, 20 are each rotated by the same amount relative to the camshaft drive wheel, so that the spread s is changed to the same extent for both cams 11, 12; however, phasing, ie a change in the phase angle p that may exist between the two cams 11, 12 does not occur in this case.
If, on the other hand, the second adjusting bolt 40 is moved in or against the arrow direction 4 in addition to the first adjusting bolt 30 or independently of it, this leads to an additional rotation of the second camshaft 20 with respect to the first camshaft 10 due to the helical teeth 23, and thus to a change of the phase angle P.

In this context, it is of particular importance that the second adjusting pin 40 is provided with straight teeth 33 at one end and with helical teeth 23 at the other end, although it would of course also be possible to provide the straight teeth between the second adjusting pin 40 and the second camshaft 20 and the helical toothing between the second adjusting bolt 40 and the first adjusting bolt 30. It is essential that, due to the system, significantly higher frictional forces occur in the area of the helical teeth 23 than in the area of the straight teeth 33. This means that with the arrangement shown, starting from the position shown in FIGS. 5, 6, when the adjusting bolt 30 is slightly in Arrow direction 4 is shifted to the left, the second adjusting pin 40 is not taken due to the higher frictional forces in the area of the helical teeth 23. Rather, with a slight displacement of the first adjusting bolt 30 in the direction of arrow 4, a relative movement occurs between the first adjusting bolt 30 and the second adjusting bolt 40.

If, on the other hand, starting from the position shown in FIGS. 5, 6, the first adjusting bolt 30 is shifted to the right in the direction of the arrow 4, this also causes one since the second adjusting bolt 40 lies in the central recess 34 of the first adjusting bolt 30 against the stop 60a Displacement of the second adjusting bolt 40 against the direction of the arrow 4.
This means that when the adjusting bolt 30 is moved in the direction of the arrow 4, starting from the position shown, only the spread s of the cams 11, 12 is changed, but the phase angle p between these cams remains unchanged. On the other hand, when the first adjusting bolt 30 is displaced in the direction of the arrow 4, the phase angle p is also changed in addition to the spread s.

The previous explanations apply in the same way to the two exemplary embodiments in FIGS. 5, 6. In the same way, in the two exemplary embodiments, a head screw-like pin 61 is also screwed into the left-hand end face of the second adjusting bolt 40. This pin 61 penetrates a web 62 of the first adjusting bolt 30, a recess 63 being provided for the head of the pin 61 in the first adjusting bolt 30 on the left side of the web 62.
The purpose of this pin 61 screwed into the second adjusting bolt 40 is as follows: As already explained, starting from the position shown, the first adjusting bolt 30 can be moved to the left in the direction of the arrow 4 to adjust the spread s without changing the phase angle p. After a displacement by the distance x, the web 62 comes to a stop at the head of the pin 61; this stop is designated by the reference number 60 b. If the first adjusting bolt 30 is now moved further in the direction of the arrow 4, the second adjusting bolt 40 is carried along during this displacement movement. In this way, in addition to the spread s, the phase angle is also p is adjusted between the first cam 11 and the second cam 12. This stop 60b, like the stop 60a already explained, thus forms a means with which, depending on boundary conditions, a relative movement between the adjusting bolts 30, 40 can be prevented. In the case described, these boundary conditions relate to the position of the first adjusting bolt 30 with respect to the second adjusting bolt 40, since depending on this position either one of the stops 60a, 60b acts as a means to prevent a relative movement between the adjusting bolts 30, 40 or a relative movement between these adjusting bolts 30, 40 is made possible.

In the exemplary embodiment according to FIG. 5, a further means is provided which, depending on boundary conditions, is able to prevent a relative movement between the adjusting bolts 30, 40. This means is an adjustable or releasable clamping body and is designed in detail as a chain of thorns 71, 73, 72 connected in series. The mandrels 71 and 73 are mounted in the first adjusting bolt 30 such that they can be displaced transversely to the longitudinal axis 14 of the shaft, ie, in the direction of the axis 74. The mandrel 72 is also mounted in the head screw-like pin 61 so that it can be displaced transversely to the shaft longitudinal axis 14. If, starting from the position shown, the first adjusting bolt 30 is moved by the distance y in the direction of arrow 4, the mandrels 71, 73, 72 with the same diameter come to lie one above the other, ie all the mandrels lie on the same axis 74 hydraulic system 80, which engages the mandrel 71, the mandrel 71 partially penetrate into the receiving hole provided in the pin 61 for the mandrel 72. As a result, the pin 72, like the mandrel 71, is pushed upward in accordance with the drawing and thus partially reaches the receiving bore for the mandrel 72 provided in the adjusting bolt 30 a spring element 75, which is clamped between the mandrel 73 and the wall of the adjusting bolt 30, is compressed. The pin 61 is now locked with the first adjusting bolt 30 via the mandrels 71, 72. This means that the activation of the hydraulic system 80 described, by means of which the mandrel 71 is still displaced upward, the first adjusting bolt 30 is locked with the second adjusting bolt 40. The boundary condition in which a relative movement between the two adjusting bolts 30, 40 is thus prevented by this lockable clamping body or by the mandrels 71, 73, 72 is again a defined position between these two adjusting bolts. In addition, hydraulic control is possible or required.

This clamping element is unlocked by reducing the pressure in the hydraulic system 80 by utilizing the force of the spring element 75. With decreasing hydraulic pressure, it is namely possible for this spring element 75 to move the mandrel 73 again in such a way that the mandrel 72 is completely inserted into the pin 61 is pushed, so that the mandrel 71 thereby completely reaches the first adjusting bolt 30 again. If, for example, an electronic control unit that evaluates any boundary conditions, such as the current operating point of the internal combustion engine in its operating map, evaluates the pressure in the hydraulic system 80, it is again possible to release the clamping body or the mandrels as described and thus to decouple the two adjusting bolts 30, 40 from one another. Thereafter, a relative movement between these two adjusting bolts 30, 40 is again possible.

In summary, this means for the embodiment according to FIG. 5 that, starting from the position shown, initially the adjusting bolt 30 can be moved by the distance y in the direction of the arrow 4, the second adjusting bolt 40 retaining its position shown due to the relationships described above (different coefficients of friction in the straight toothing 33 and the helical toothing 23). This means that with a displacement movement by the distance y, only the spread s is changed, the phase angle p between the first cam and the second cam 12, however, remains unchanged. After a displacement by the distance y, however, the two adjusting bolts 30, 40 can be locked together. With a further displacement of the first adjusting bolt 30 in the direction of arrow 4, the second adjusting bolt 40 is now taken along, so that in addition to the spreading s, the phase angle p is also changed. This locking between the two adjusting bolts 30, 40 is maintained until, for example, triggered by an electronic signal, the hydraulic system 80 is deactivated, so that the locking is released again by the spring element 75 as described above. Proceeding from this, with a further displacement of the adjusting bolt 30 in the direction of arrow 4, only the spread s is changed, while the adjusting bolt 40 then retains its position, so that the phase angle p remains constant. This applies until the adjusting bolt 30 or its web 62 comes to a stop 60b with the pin 61 of the adjusting bolt 40. Now, as also already explained, a further displacement of the adjusting bolt 30 in the direction of arrow 4 likewise causes the adjusting bolt 40 to be displaced, so that now, in addition to the spreading s, the phase angle p is also increased again. All in all, there are a multitude of adjustment possibilities, and in particular the relationships explained in FIG. 2 can also be realized. The situation for FIG. 5 was explained with a displacement movement of the first adjusting bolt 30 in the direction of arrow 4; the same applies of course also for the opposite direction of movement.

6 also has the two adjusting bolts 30, 40 and the head screw-like pin 61 provided in the second adjusting bolt 40, so that the two stops 60a, 60b also come into effect in this exemplary embodiment. As a further means, which prevents a relative movement depending on boundary conditions between the two adjusting bolts 30, 40, however, a propulsion means 90 is provided for the second adjusting bolt 40. This propulsion means 90 is actuated again by a hydraulic system which bears the reference number 80. As can be seen, the propulsion means 90 is designed as a piston which is connected to the second adjusting pin 40 and which is guided within a cylinder which is formed by a recess 81 in the second camshaft 20. As is usual with hydraulic cylinder-piston systems, a supply / disposal channel 82 is provided on each end of the cylinder or the recess 81. By appropriately filling the recess 81 on the left or right side of the piston or the propulsion means 90, it is thus possible to move the propulsion means 90 and thus also the second actuating piston 40 as desired. By correspondingly controlling the hydraulic system 80, the second adjusting bolt 40 can thus be positioned in such a way that one of the two stops 60a, 60b takes effect or that the first adjusting bolt 30 can be moved without taking the second adjusting bolt 40 with it. The control of the hydraulic system 80 is extremely simple to implement, since it only has to be ensured that either one of the stops 60a, 60b comes into effect, or that a relative movement between the two adjusting bolts 30, 40 is possible. On the other hand, it is not absolutely necessary to use the propulsion 90 to position the second adjusting pin 40 in the desired manner so precisely that a defined phase angle is established between the first cam 11 and the second cam 12. This can essentially be achieved by suitable coordination of the helical teeth 23 in connection with the respective positions of the first adjusting bolt 30.

In sum, it is thus possible with the arrangements shown to either change only the spread of the associated valve lift curves on a reciprocating piston internal combustion engine with at least two gas exchange valves per cylinder or to additionally vary the phase angle between these two valve lift curves. This is done with the help of one or both adjusting bolts 30, 40, which cause a corresponding twisting movement of the camshafts 10, 20 assigned to the respective gas exchange valves via helical gears. If the two adjusting bolts 30, 40 are moved in FIGS. 4 to 6, then in addition to the spreading s the phase angle p is also changed, whereas only the first adjusting bolt 30 is moved, this merely causes a change in the spreading s. A relative movement between the two adjusting bolts, which occurs in FIGS. 5, 6 when only the first adjusting bolt 30 is moved, is made possible by the fact that a straight toothing is provided between the first adjusting bolt 30 and the second adjusting bolt 40, while between the second adjusting bolt 40 and the camshaft 20 associated therewith a helical toothing which produces higher frictional forces is provided. 5, 6, the means already described are provided, with the aid of which such a relative movement can be prevented.

Claims (11)

1. A reciprocating internal combustion engine with at least two, especially parallel-acting, gas exchange valves per cylinder actuated by cams (11, 12) which are adjustable relative to one another and whose camshafts are concentric with one another, wherein the phase angle (p) between the cams (11, 12 or 1, 2) and also the phase position (spread s) between all the, especially parallel-acting, cams (11, 12 or 1, 2) and the crankshaft co-operating with the reciprocating piston are variable,
   characterised in that two setting bolts (30, 40) movable in the longitudinal direction of the shaft (14) and disposed concentrically with one another are provided for individual adjustment of the, especially both, camshafts (10, 20) relative to the crankshaft and are connected via respective helical gears (31, 23) on the one hand to the associated camshaft (10, 20) and on the other hand to a camshaft-driving wheel (15).
2. An engine according to claim 1,
   characterised in that the setting bolts (30, 40) bear pistons (51, 52) which divide a common hydraulic chamber (50) for the, especially both, pistons (51, 52) into, more particularly, three hydraulic compartments (53, 54, 55) connected in series.
3. An engine according to claim 2,
   characterised in that the hydraulic compartments (53, 54, 55) are connectable via individual valves (56) to a hydraulic system in order to obtain desired pressure conditions between the hydraulic compartments by individual actuation of the valves (56), thus moving the required setting bolts (30, 40) as required.
4. An engine according to claim 2 or claim 3,
   characterised in that the hydraulic chamber (50) is incorporated in the camshaft-driving wheel (15).
5. An engine with at least two, especially parallel-acting, gas exchange valves per cylinder actuated by cams (11, 12) which are adjustable relative to one another and whose camshafts are concentric with one another, wherein the phase angle (p) between the cams (11, 12 or 1, 2) and also the phase position (spread s) between all the, especially parallel-acting, cams (11, 12 or 1, 2) and the crankshaft co-operating with the reciprocating piston are variable,
   characterised in that two setting bolts (30, 40) movable in the longitudinal direction of the shaft (14, arrow 4) are provided for adjusting the two camshafts (10, 20) relative to the crankshaft, the first setting bolt (30) being connected to the first camshaft (10) and to a camshaft-driving wheel (15) via respective gears (17), at least one of which is a helical gear, and the second setting bolt (40) being connected to the second camshaft (20) and to the first setting bolt (30) via respective gears (33, 23), one of which is a helical gear (23) and one is a spur gear (33), and a means being provided preventing relative movement between the setting bolts (30, 40) in dependence on boundary conditions.
6. An engine according to claim 5,
   characterised in that the means preventing relative motion between the adjusting bolts (30, 40) is in the form of

   - an abutment (60a, 60b) between the adjusting bolts and/or

   - a lockable or releasable clamping member and/or

   - propulsion means (90) for the two setting bolts (40).
7. An engine according to claim 6,
   characterised in that a hydraulic system (80) is provided for locking and releasing the clamping member and/or for the propulsion means (90).
8. An engine according to any one of claims 5 to 7,
   characterised in that a first direct abutment (60a) for one direction of motion and a second abutment (60b) for the other direction of motion, starting from the first abutment (60a) and allowing some relative motion, are provided between the two setting bolts (30, 40).
9. An engine according to claim 8,
   characterised in that the second abutment (60b) is in the form of a cap screw-like bolt (61) inserted in the end face of the second setting bolt (40) and co-operating with a web (62) on the first setting bolt (30).
10. An engine according to any one of claims 5 to 9,
    characterised in that the clamping member mounted in one of the setting bolts (30) is at least one mandrel (71, 72, 73) engaging in a recess in/on the other setting bolt (40) and movable by a hydraulic system (80) and/or by a spring element (75).
11. An engine according to any one of the preceding claims,
    characterised by at least one of the following features:

    - the second camshaft (20) is disposed inside the first camshaft (10),

    - the second camshaft (20) is formed at its end face with a recess (22) extending in the longitudinal direction (14) of the shaft and the wall of which has helical gearing at places (23),

    - the setting bolt (40) with helical gearing (32) projects into the recess (22),

    - the inner camshaft (20) is a solid shaft to which the cams (12) are secured by a bolt (21) passing through.

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