DE2037705A1 - Valve control system for vehicle internal combustion engines - Google Patents

Description

PATENT LAWYERS MUNICH 2
VAL 33
TEL. 0811/226894
295051
CABLES: THOPATENT
TELEX: TO FOLLOW Dipi.chem. Dr D. Thomsen oipung. H. Tiedtke
Dipi.-chem. G. Bühling 20377 05 FRANKFURT (MAIN) 50
FUCHSHOHL 71
TEL 0911/514366 Dipi.-ing. W.Weinkauff

Reply requested to: Please reply to:

8000 Munich 2 July 29, 1970 T 3768 / case PG23-6953

Nissan Motor Company, Limited Yokohama City / «Japan

Valve control system for vehicle internal combustion engines

The invention relates to a system for controlling the timing of valves for a vehicle internal combustion engine and in particular to a valve control system that works as a function of the operating conditions of the engine.

_t The opening and closing movement of the inlet and '

I ν

Exhaust valves of a cylinder of a vehicle internal combustion engine are usually controlled in such a way that they provide an optimal output

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booty of the engine while driving the motor vehicle. However, when the motor vehicle is driven at relatively low speeds, as in city driving, the performance of the engine is more or less degraded, as a result of which an increased amount of unburned or partially burned exhaust gases are emitted, which contain harmful compounds such as hydrocarbons and carbon monoxide, causing serious pollution of atmospheric air in urban areas. After one of the numerous proposed to solve such a pollution problem possibilities, the exhaust valve is opened at a delayed time in practice, so that the ignited gases for a prolonged period of time at high temperature and high pressure to remain in the engine cylinder, whereby the hydrocarbons and Kohlenstoffmonoxyde fully burned will. Although there is a reduction in the unburned, toxic components of the exhaust gases, especially at low engine speeds and / or:

light load condition of the motor vehicle, the opening of the exhaust valve at a delayed point in time is accompanied by a decrease in power of the engine at high speed and / or heavy load condition. This difficulty persists insofar as the valve core is controlled or delayed without taking into account the conditions under which the engine is operating.

It is an object of the invention to provide a valve control system in a vehicle internal combustion engine with engine cylinders each having intake and exhaust valves which is rotatable together with the crankshaft of the engine

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Camshaft has, which is axially movable via a cam supporting bearing, dag on the swing lever of each engine cylinder housing is mounted; the camshaft has first and second cam lobes disposed opposite the swing arm of the exhaust valve; the second cam lobe is larger in size than the first cam lobe; a cylinder part is connected to the rocker arm housing and disposed opposite to the leading end of the camshaft; the cylinder part is provided with a stop which is arranged for working contact with the leading end of the camshaft; a piston disposed on _f the cam shaft at a portion near the leading end fixed and is located Xn the cylinder member to define therebetween a chamber; A compression spring sits between the support bearing and the piston in order to press the piston and the camshaft to the stop; a hydraulic fluid supply channel communicates at one end with a hydraulic pressure medium and at the other end with the chamber; a hydraulic fluid discharge passage communicates with the chamber; valve means for selectively opening and closing the hydraulic fluid discharge passage; and control means for controlling the valve means to normally open the hydraulic fluid discharge passage and close the discharge passage when the engine is operating at a speed lower than a predetermined value and the negative pressure in the intake manifold of the engine is higher than a predetermined value; the first cam lobe rests against the swing arm by the action of the compression spring normally when the valve device is in one position

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- If -

is located in which the hydraulic fluid discharge channel is open, and the second cam lobe is pressed against the swing arm when the valve device is moved to a position in which it closes the hydraulic fluid discharge channel and so the piston and the camshaft in the axial direction moved away from the stop against the action of the compression spring. The control device comprises a solenoid valve device having a movable core rigidly connected to the valve device and a solenoid coil operatively connected to a source of electrical power, a first switch positioned between the solenoid coil and the source of electrical power, which switches to the.
Speed of rotation of the engine responds and is closed when this is lower than a predetermined value, a second switch connected in series with the first switch, which responds to the negative pressure in the intake manifold of the engine and is closed when the negative pressure at the inlet Suction pipe is higher than a predetermined value. If desired, the camshaft may have a different set of first and second cam lobes which are disposed opposite the swing arm of the intake valve and the latter of which is larger in size than the former; the one assigned to the inlet valve
the first cam lobe normally rests on the swing arm of the inlet valve by the action of the compression spring when the valve device is in a position in which it opens the hydraulic fluid discharge channel, and the second cam lobe assigned to the inlet valve is moved against the swing arm of the inlet valve, when the valve device is moved into a position in which it closes the deru b ^ raiais, chen fluid discharge channel

und.so the piston and the camshaft against the action of the compression spring moved away from the stop.

In the following the invention is based on the drawing explained in more detail using exemplary embodiments.

Fig. 1 shows a sectional view of an embodiment

shape of the valve spreader system according to the invention,

FIG. 2 shows one taken after H-II of FIG

View of an essential part of the valve control system according to the invention,

Fig..3 shows a scheme of a preferably chosen Example of a control device for use in the valve control system according to the invention »

Fig.Ή shows a graph showing an example of the area in which the working _f erf indungsgemäße system,

Fig. 5 is a diagram showing the drain valve timing represents the system according to the invention,

Figure 6 is a graph of the dependency between the valve lift and the crankshaft

len rotation angle with one the invention 009886 / T645

according to the valve control system having engine,

Fig,? shows a perspective view of essential parts of a modified form of the invention Valve control system,

Fig. 8 is a diagram illustrating the intake valve timing of the system of Fig. 7;

FIG. 9 shows the same relationship as FIG. 6, however, in the system according to FIGS. 7 and

Fig. 10 'shows diagrams showing the dependency between Engine speed, the negative pressure on the intake manifold and those within the operating range of the valve control system of the present invention Represent vehicle speed.

The valve control system according to the invention shown in FIG. 1 is used in an engine cylinder which has a rocker arm housing 10. In the rocker arm housing 10, a drain valve 12 is provided which is operatively connected to a rocker arm 14 via a valve spring plate 16. The drain valve 12 is axially displaceable to open and close a drain port (not shown) and to allow exhaust gases, and is normally on its seat by action of the

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Compression spring 18 held. The swing arm is supported by external pins 20 carried pivotably, as can be seen clearly from FIG.

A camshaft 22 is mounted on the cylinder via a camshaft gear or sprocket 24 with which the camshaft 22 is splined. The sprocket 24 is of of the crankshaft (not shown) so that the camshaft 22 is rotatable together with the crankshaft. Since the Camshaft 22 is serrated with the chain sprocket 24, this is the case

axially movable within the rocker arm housing 10. The reference number 26 denotes a setting element with which the Sprocket 24 is adjusted in a suitable manner. The camshaft 22 is rotatably and axially movably supported by a camshaft support bearing 28 which is fixed with respect to the cylinder. A lubricant channel 28a can be formed in the support bearing 20, to smooth the rotation and axial movement of the camshaft 22.

A first cam lobe 30 and a second cam lobe 32 are formed on the camshaft 22 and Swing arm IU of the drain valve 12 is arranged. Between the leading end the camshaft 22 and the end wall of the rocker arm housing 10 is arranged a cylinder member 34 which is attached to the rocker arm housing is attached. The cylinder member 34 is arranged opposite the guide end of the camshaft 22 and has on its inner wall surface a stop 36 for limiting the axial movement of the camshaft 22. A piston 38 is mounted on the by a bolt 40 Camshaft 22 attached to a portion near the leading end thereof.

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The piston 38 sits in the cylinder member 34, so that a chamber 42 is formed in between. A compression spring 44 sits between Support bearing 28 and the piston 38 via a thrust bearing 45 which is attached to the piston 38, as shown, is arranged.

The chamber 42 has one side with a hydraulic one Fluid inflow channel 46 and on the other side with a hydraulic fluid discharge channel 48 in connection. The hydraulic one Fluid inflow channel 46 is in turn connected via an opening 50 to a hydraulic fluid tunnel 52, and the hydraulic one Fluid drainage channel 48 is in turn connected to a drainage chamber , 54 in connection. The tunnel 52 is in communication with a source (not shown) of hydraulic pressure medium.

The first cam lobe 30, which is to be used at high speed and / or when the motor vehicle is operated under heavy loads, is smaller in its dimensions than the second cam lobe 32, which is used at low speed and / or when the motor vehicle is traveling under a light load. The first cam projection 30 is disposed on the camshaft 22 such that it normally bears against the swing arm 14 when the piston 3 8 and, accordingly, the camshaft 22 against the stop 36 in the cylinder member 34 _o by the action of the spring 44 in the absence of a hydraulic pressure in the

to chamber 42 is pressed. The second cam lobe 32 is other o

co on the one hand arranged in such a way that they are normally out of alignment with co

^ the swing arm 14 is held when the first cam lobe 30 ^ rests on it, and is brought into contact with the swing arm 14 when a hydraulic pressure in the chamber 42 occurs, so that the piston and accordingly the camshaft 22 against the action of the spring 44 of the

Stop 36 is moved away.

The hydraulic pressure to be introduced into the chamber 44 and to be diverted from it is controlled ^{by a plunger or} valve element, the ". the hydraulic fluid discharge channel 48 is assigned. The valve member 56 is in turn controlled by a solenoid valve, generally indicated by the reference numeral 53. The reference numeral 6o denotes a discharge channel which is intended to enable a fluid pressure to be passed through when the valve member 56 is closed.

The solenoid valve 58 consists essentially of a movable core 62 which is connected to the plunger or valve member 56 is formed in one unit, a spring 64, which presses out the movable core 66, so that the "plunger or valve member 56 is held in a position in which there is the drainage channel; "" - ■, 48 closes, and a solenoid coil 66 that forms the movable core 62 moved into its retracted position when energized, so that the plunger or valve member 56 is moved to open the discharge channel 48. - '

The solenoid coil 66 is energized as a function of predetermined operating conditions of the motor vehicle, so that the valve element 56 is only in a position for opening the drainage channel 48 when the vehicle is under predetermined conditions, such as driving on land. is operated. Various operating variables of the motor vehicle can be used, turn the

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Represent operating states that affect the movement of the valve member dictate. 3 shows an example of an electrical circuit arrangement, which can preferably be used to control the solenoid valve 58.

The solenoid coil 6 6 is connected via a line 6 6a to a first switch 68, which reacts to changes in the negative pressure in the. Inlet intake manifold (not shown) of the engine responds (Fig. 3). The switch 68 is operated by a membrane device which has a membrane 72 to which the switch 68 is rigidly connected. A compression spring 74 sits on the rear side of the diaphragm 72, which is consequently pretensioned in a position in which the switch 68 is kept open. The diaphragm 72 is subjected to a negative pressure in the intake manifold of the engine, and the compression spring 70 is selected so that it overcomes the force of the negative pressure in the intake manifold, which is lower than. a predetermined level, e.g. for example -100mm Hg. When the negative pressure exceeds such a predetermined level, for example when decelerating the motor vehicle, the spring 71 overcomes the force of the negative pressure on the intake manifold so that the diaphragm 72 is moved to a position in which the switch 68 is closed. . ,

Instead of the arrangement shown in FIG. 3, the switch 68 can preferably be operated by a vacuum-controlled valve. 8 shifting device of the distributor can be controlled.

The switch _Q 68 _Q is operationally with a second QISKJINAL INSPECTED

- 11 -

Switch 76 connected via a line 78. The switch 76 can be on Be a relay switch that is normally open and energized with a voltage lower than a predetermined level. In more detail, switch 76 is operatively connected to an ignition distributor 78 by a line to detect the primary pulses generated therein. It a voltage proportional to the number of primary pulses is generated, which is then compared with a suitable reference voltage which corresponds to a predetermined engine speed - for example 3,200 rpm - whereupon the switch 76 is closed. Preferably, the switch 76 can be controlled differently, provided that it is only closed when the engine is operated at a speed lower than the predetermined value. For example the switch 76 may be through one or more fluid pressure regulators a power transmission system or a tachometer device, if available, controlled. The switch 76 can also be a function of the speed of rotation operated by an electromagnetic pickup device is established, which is arranged such that it is from w the revolution of a gear train arranged on the crankshaft depends. ·

The first and second switches 68 and 76 are each connected in series with an electrical power source 82 The power source 82 may preferably be a battery bank. '.

If the motor vehicle is on a country road or 0098 86/1 6A5

Expressway is operated and the engine speed is higher than one predetermined value (e.g. 3,200 rpm) and the negative pressure at the intake pipe lower than a predetermined value (e.g. - 100mm Hg) -i3t, then switches 6-8 and 76 are held open holding the solenoid coil of solenoid valve 58 de-energized. The plunger or Valve element 56 is accordingly advanced by the action of spring 64 held and closes the hydraulic fluid discharge channel 48. This leads to an increase in the fluid pressure in the chamber 42, so that the piston 38 and consequently the camshaft 2 2 are moved away from the stop 36 against the action of the spring 44 until 'brought the cam lobe 32 into alignment with the swing arm 14 is. The opening and closing movements of the drain valve 12 are thus controlled by rotating the larger cam lobe 32 when the motor vehicle is driven at high speed.

When, the motor vehicle is decelerating or moving with At a lower speed, such as when driving on urban roads, the engine speed decreases and the negative pressure decreases on the intake manifold so that the switches 6 8 and 76 simultaneously or one after the other (differentiel). If both switches 68 and 76 are held closed at the same time, the solenoid coil 66 of the solenoid valve 58 is energized and moves the plunger valve member 56 against the action of the spring 64 in its retracted position, whereby'es the hydraulic fluid drain passage 48 opens. The fluid pressure enclosed within the chamber 42 can now enter the drainage chamber via the drainage channel 42 54 arrive. The piston 38 and accordingly the camshaft 22 are moved against the stop 36 by the action of the spring 44,

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until the first cam lobe 30 is brought into alignment with the swing arm IM ·. The opening and closing movements of the drain valve 12 are now dictated by rotating the first cam lobe 30. '·

FIG. H illustrates an example of the range in which the two cooperating switches 68 and 76 are to be closed together, it being assumed that the first switch 68 is closed when the negative pressure at the inlet suction pipe is greater than, for example, -100 mm Hg and the second switch is closed when the engine speed is lower than, for example, 3,200 rpm.

The first cam lobe 30, which is used to regulate the valve insert during Hochgeschwxndxgkeits- and / or heavy duty operation of the motor vehicle, is shaped so that the drain valve 12 is preferably opened at about 50 ° before bottom dead center (BDC) of the piston movement of the engine or cylinder and about £> - preferably about 10 ° - after top dead center (TDC) closed- ™. ' sen, as shown in FIGS. 5 and 6 can be seen. The second cam lobe 32, which is used to regulate the movements of the drain valve 12 at low speed and / or light load operation of the motor vehicle, is shaped such that, as shown in FIGS. 5 and 6, the drain valve 12 is preferably 50 ° before bottom dead center is opened and is essentially closed at top dead center. As can be seen from Fig. 6, the valve lift is smaller when the second cam lobe 32 is operated than when operating

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wise about 10 ° - is opened before top dead center and preferably is closed at 50 ° after bottom dead center. The second cam lobe 96 operating at low speed and / or light-duty driving ι the motor vehicle is operated, is shaped so that the inlet valve 8 6 is substantially in the upper Dead center is opened and closed slightly before the point at which the inlet valve is closed when the cam lobe 96 is operated. This results from FIG. 8. FIG. 9 illustrates that the valve lift during operation of the cam lobe 9U measurable. is greater than when the cam lobe 96 is in operation.

Fig. 10 shows how the engine speeds and the negative pressure on the intake manifold - both of these quantities are used as beneficial variables in representing the driving conditions of the motor vehicle used in the system according to the invention - itself with the driving speeds of the motor vehicle markedly change, from which it follows that the working range of the valve control system is designed can be achieved that the desired control of the valve core in accordance with the driving conditions of the motor vehicle will.

From the foregoing description it follows that the drain valve or both the drain valve and the inlet valve for satisfactory combustion of the fuel-air mixture in the engine cylinder can be controlled in terms of time without a significant loss of power through the changing driving conditions of the motor vehicle is effected.

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To achieve the satisfactory combustion of the hydrocarbons and carbon monoxides in the fuel-air mixture It is also important that there is a sufficient amount of oxygen in the fuel gases supplied to the engine cylinder is included. For this purpose, an engine that can be operated with a relatively lean fuel-air mixture is proposed and used; when using an engine of this type, it is necessary to appropriately adjust the fuel-air mixture to each of the engine cylinders to spread the mixture evenly through the entire • combustion chamber and create a turbulent flow of the Build fuel-air mixture in the combustion chamber. This is done by throttling the inlet port of the engine cylinder reached through the inlet valve to thereby "squeeze" the mixture to be passed through (squeeze '/. The one shown in FIG modified embodiment of the valve control system according to the invention is advantageous for this purpose, as the valve lift is significantly limited at low speed and / or light load driving, when a larger amount of unburned exhaust gases is usually discharged becomes, '' ■ ·

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Claims (1)

Claims .y valve control system for vehicle internal combustion engines with engine cylinders, each having intake and exhaust valves, characterized by a camshaft (22) rotatable together with the crankshaft of the engine, axially displaceable via a support bearing (28) firmly connected to the engine cylinder and a first and second cam lobes (30,32) which are arranged opposite the swing arm 'CL4) of the exhaust valve (12) and of which the second cam lobe (32) is larger in size than the first cam lobe (30), with a Cylinder member is fixed opposite the engine cylinder and is arranged gegenbsr the leading end of the camshaft and is provided with an An3 ± 3ag (36) which is arranged for working contact with the leading end of the camshaft, furthermore a piston (38) fixed on the camshaft in one Section near the leading end thereof is mounted and seated in the cylinder member to form a chamber (42) therebetween, where wide rhin a spring (U ¹ O is placed between the support bearing and the piston to press the piston and the camshaft to the stop, with a hydraulic fluid 00988 6/1645 Feed channel (46) at one end with a source one below Pressurized hydraulic medium and is connected at the other end to the chamber, furthermore a hydraulic fluid discharge channel (28) is in communication with the chamber, wherein a valve device for selective opening and closing, des.hydraulischen Fluid discharge channel is provided, and by a control device for controlling the valve device to the hydraulic Keep the fluid drain channel normally closed and the drain channel. to open when the engine is operated at a speed less than a predetermined value and the negative pressure on the intake manifold of the engine is higher than a predetermined value, the second cam lobe being held in abutment with the swing arm when the valve device in a position to close the hydraulic Fluid drainage channel is located around the piston and the camshaft move axially away from the stop against the compression spring and move the first cam lobe into abutment with the swing arm;. "" "; when the valve device is in a position to open the hydraulic Fluid discharge channel "· is moved to the piston and the. To move the camshaft axially against the stop by the action of the compression spring. · ' 2. System according to claim 1, characterized in that the camshaft (22) has a further set of an er.sten (94) and second (96) cam lobes which are arranged opposite the swing arm (88) of the inlet valve (86) and from which the latter is larger in dimensions than the former, that further 009886/1645 2P377Q5 the . the inlet valve associated second Npckenbühung on the Swing arm of the inlet valve rests when the valve device is in a position in which the hydraulic fluid ■ discharge channel (48) is closed in order to move the piston (38) and the camshaft axially away from the stop (36) against the compression spring (44) » and that the first. . cam associated with the intake valve. Elevation moves to rest on the swing arm of the intake valve when the valve means is moved to a position in which it opens the hydraulic fluid discharge passage, around the piston and the camshaft through the action of the compression spring axially .. against the Stop to move. 3. System according to claim 1 or 2, characterized in that the valve means has a solenoid valve (58) with a movable core (62) rigidly connected to the valve means, a solenoid coil (66) operatively connected to: a source of electrical power and a spring ( 64), which moves the movable core into a position in which the valve device. is advanced to close the drain channel (48), that a first switch (76) is also connected between the solenoid coil and the electrical power source and responds to the speed of rotation of the motor that this first switch continues to be closed is, if the speed of rotation is less than a predetermined value, that a second switch (68) connected in series with the first switch also responds to the negative pressure in the intake manifold of the engine and that finally it. is closed » when the negative pressure on the intake manifold. ' 009886/1645 ϊ77Ό5. is higher than a predetermined value. 1. System according to one of claims 1 to 3, characterized in that the - the exhaust valve (12) associated first cam lobe (30) is shaped such that it opens the exhaust valve before the bottom dead center of the piston movement in the engine cylinder and this immediately after the top dead center of the piston closes in the engine cylinder, and the second the outlet valve MPs cam lobe (32) is shaped such that it Mk the exhaust valve after the bottom dead center of the piston in the Motorzylinder'öffnet and substantially at top dead center of the piston closes. 5. System according to one of claims 2 to H, characterized characterized in that the inlet valve (8b) associated first Cam lobe (94) is shaped such that it is the intake valve immediately before the top dead center of the piston in the engine cylinder: opens and it closes after the bottom dead center of the piston in the engine cylinder, and that the second associated with the inlet valve Cam lobe (96) is shaped such that it is the intake valve substantially in the top dead center of the piston in the engine cylinder opens and this closes after the bottom dead center of the piston m the engine cylinder much later than at the time which the inlet valve is closed by the first cam lobe associated with the inlet valve. 6. System according to one of claims 1 to b, characterized 0 0 9 8 8 6/1645 characterized in that the first cam lobe (3OJ shaped in this way is that it opens the exhaust valve (12) about 50 ° before bottom dead center and it closes about 10 ° after top dead center, and that the second cam lobe (32) is shaped such that it opens the exhaust valve at about 50 after bottom dead center. 7..System according to one of claims 2 to 6, characterized in that the * the inlet valve (86 associated first Cam lobe (94) is shaped such that it opens the inlet valve at about 10 ° before top dead center and it opens at about 50 ° closes after bottom dead center, and that the. the inlet valve associated second cam lobe (96) is shaped such that they the inlet valve at a noticeably smaller angle than 50 closes after bottom dead center. Q09886 / 1645 AA Empty soap