JPH07111128B2 - Variable valve lift controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a valve lift variable control device that variably controls lift characteristics of intake / exhaust valves according to an operating state of an engine.

<Prior Art> A valve lift variable control device of this type is constructed by contacting a rocker arm as proposed by the present applicant in, for example, JP-A-60-26109 and JP-A-60-224909. The lift control cam is provided with a lever that forms a fulcrum of the rocker arm and a lift control cam that has a plurality of cam surfaces that change the rocking position of the rocker arm by engaging the lever and changing the swing position of the lever. The intake / exhaust valve lift variable mechanism that changes the lift characteristics of the intake / exhaust valve according to the stepwise change of the engine is detected, and the operating state of the engine such as the engine speed and throttle valve opening is detected to operate the engine. Some lift control cams are switch-controlled so as to select a predetermined cam surface according to the state area.

Therefore, when this is applied to the intake valve, for example, during the idling operation, the lift characteristic of the intake valve is set to a small lift amount,
Stable combustion can be obtained by setting a small operating angle, fuel consumption can be greatly saved, and high filling efficiency can be obtained by setting the intake valve lift characteristics to a large lift amount and a large operating angle during high-speed and high-load operation. , The output of the engine can be improved.

<Problems to be Solved by the Invention> However, in such a valve lift variable control device, even when the engine lubricating oil temperature (hereinafter referred to as oil temperature) or cooling water temperature (hereinafter referred to as water temperature) is high. If the valve lift variable control according to the engine operating state is performed as usual, the following problems occur. When the intake / exhaust valve lift amount is controlled to be large in the above high temperature state, the output increases due to the increase in the intake air amount, and the oil and water temperatures rise further due to the increase in the amount of heat generated, resulting in an overheat condition and the lubricating oil. Due to the decrease in the lubrication performance due to the decrease in viscosity and the decrease in the cooling performance of the cooling water, engine scuffing and seizure are likely to occur. There was a case where the vibration damping function due to became defective and the abnormal noise was easily generated.

The present invention has been made in view of such conventional problems, and an object thereof is to solve the above problems by preventing an abnormal rise in oil temperature or water temperature by improving valve lift control.

<Means for Solving Problems> Therefore, according to the present invention, as shown in FIG. 1, a variable intake / exhaust valve lift mechanism a for varying the lift characteristics of the intake / exhaust valve.
And an operating condition detecting means b for detecting the operating condition of the engine.
And a valve lift variable control device including a control means c for switching and controlling the intake / exhaust valve lift variable mechanism so as to select a predetermined lift amount according to the region of the operating state of the engine. When the temperature of the engine and the temperature of the engine exceed a predetermined temperature set close to a high temperature state corresponding to overheat, the lift characteristics of the intake / exhaust valve are lifted regardless of the region of the engine operating state. The control means e for high temperature for controlling the variable intake / exhaust valve mechanism is provided so as to be small.

<Operation> In the above configuration, when the engine temperature detecting means detects that the engine is in a high temperature state, the high temperature control means reduces the lift characteristic of the intake / exhaust valve to a small lift amount.・ Exhaust valve lift variable mechanism is controlled.

As a result, the intake air amount is suppressed to a low level, and the rise of the engine output is controlled to prevent the oil or water temperature from rising excessively.

<Example> An example of the present invention will be described below with reference to FIGS. 2 to 9.

First, the structure of the intake / exhaust valve lift variable mechanism will be described.

As shown in Fig. 2, the suction and
A rocker arm 13 is provided by contacting both ends of the exhaust valve drive cam 11 and the stem end of the intake / exhaust valve 12. A lever 15 is provided which is in fulcrum contact with the curved back surface 13a of the rocker arm 13 and holds the shaft 13b protruding from both side walls of the rocker arm 13 in the groove 15a via the holding member 14. A spring 16 having a small spring constant is interposed between the spring seat 15b formed on the lever 15 and the holding member 14 to urge the rocker arm 13 downward in FIG.

Further, the spherical lower end surface of the hydraulic pivot 19 fitted and held in the bracket 18 attached to the cylinder head 17 is a lever.
15 of the intake / exhaust valve 12 is fitted into a recessed portion 15c formed on the top wall of the end portion on the stem end side, and the lever 15 is swingably supported around the fitting portion, and is attached to the bracket 18. On the other hand, a lift control cam mounted so as to rotate freely as described later.
20 contacts the top wall of the end of the lever 15 on the intake / exhaust valve drive cam 11 side to regulate the swing position of the lever 15.

The lower end surface of the hydraulic pivot 19 is a recess 15c of the lever 15.
And an outer cylinder 19a whose peripheral surface is slidably fitted in the mounting hole 18a of the bracket 18 and an inner cylinder 19b fitted in the outer cylinder 19a, and between the both. The formed hydraulic chamber 19c is provided with a check valve 19d. Then, from the hydraulic pressure supply passage 18b formed inside the bracket 18 to the inner cylinder 19b.
Hydraulic pressure is supplied to the hydraulic chamber 19c through the inside and the check valve 19d to keep the valve clearance constant.

The lift control cam 20 has six substantially flat cam surfaces 20 for changing the lift amount of the intake / exhaust valve 12 stepwise on the outer peripheral surface.
The cam control shaft 21 which has a to 20f and which will be described later is provided at the center.
It has a hole 20g for inserting. The outer peripheral surface of the cylindrical portion 20h formed so as to project from both sides of the lift control cam 20 has a lower arc groove 18c formed in the bracket 18 and the upper surface of the cylindrical portion 20h, as shown in FIGS. 3 and 4. It is rotatably held between an upper arc groove 23a formed in a pair of caps 23 fastened with a bolt 22.

Then, one cam control shaft 21 is passed through a hole 20g formed through the center of the lift control cam 20 provided in several cylinders,
As shown in FIG. 3, each lift control cam of the cam control shaft 21
20 Torsion coil spring fitted on both sides 24
Screw 21 with one end of the screw screwed onto the outer peripheral surface of the cam control shaft 21
While being locked to a, the other end of the torsion coil spring 24 is fitted and locked in a hole formed in the end surface of the cylindrical portion 20h of the lift control cam 20.

One end of the cam control shaft 21 has a joint as shown in FIG.
A drive shaft 26 a of an actuator (eg, stepping motor) 26 is connected via 25. Actuator 2
6 rotates the cam control shaft 21 driven by the drive signal SK from the control rotation 27.

Reference numeral 28 in FIG. 2 is a valve spring.

Next, the configuration of the control circuit 27 will be described with reference to FIG. The control circuit 27 has a function as control means,
It is mainly composed of a CPU 30, a ROM 31, a RAM 32 and an I / O port 33. CPU30 operates by clock 34 regularly, ROM
According to the program written in 31, the required external data is fetched from the I / O port 33, and the data is exchanged with the RAM 32 via the bus line 35, and the arithmetic processing is performed. The data is output to the I / O port 33 in accordance with. The RAM 32 temporarily stores external data.

On the other hand, the engine speed NE is detected as a speed signal by a speed sensor 36 composed of, for example, a crank angle sensor, and the throttle valve opening CV is detected by a throttle valve opening sensor 37 to be an A / D converter. After being converted into digital signals by 38, they are input to the I / O ports 33 as post-throttle valve opening signals. Further, the neutral position of the gear of the transmission is detected by the neutral switch 39 as a neutral signal, the depression of the clutch is detected by the clutch switch 40 as a clutch depression signal, and the lubricating oil temperature is set to a predetermined value by the oil temperature switch 44. , And the cooling water temperature is input to the I / O port 33 by the water temperature switch 45 as a comparison signal with a predetermined value. Also,
The rotational position of the cam control shaft 21 is detected by a potentiometer 41 (a position detection switch may be used) and the A / D converter 42 is detected.
After being converted into a digital signal by
Input to I / O port 33. In addition, the actuator 26
An operation / non-operation signal SA for detecting the operation / non-operation of is input to the I / O port 33 via the drive circuit 43. The rotation speed sensor 36, the throttle valve opening sensor 37, the neutral switch 39 and the clutch switch 40 constitute an engine operating state detecting means as a whole, and the oil temperature switch 44 and the water temperature switch 45 constitute an engine temperature detecting means. Control circuit
27 is each signal from the operating state detection means, actuator 26
Based on the actuation / non-actuation signal SA from and the rotation position signal Vpos of the cam control shaft 21, the control value (rotation amount of the cam control shaft 21,
The rotation direction) is calculated, and the drive signal SK is supplied via the drive circuit 43 so as to select a predetermined cam surface from the cam surfaces 20a to 20f.
Is output to the actuator 26.

Next, the operation will be described.

FIGS. 6A and 6B are flowcharts showing a control program for switching control of the lift control cams written in the ROM 31, and P _{1 to} P _{32 in the} drawings show respective steps of the flowchart. This program is for example engine 1
It is executed every rotation.

First, the operation state determination flow consisting of P _{1 to} P ₁₀ and P ₃₁ and P ₃₂
UHF determines the operating status of the engine. P _{1 to} P ₁₀ and P ₃₁ ,
P ₃₂ determines the following conditions respectively.

P ₁ : Throttle valve fully closed P ₂ : Clutch pedal depressed P ₃ : Gear in neutral position P ₄ : Rotational speed NE in 600 ± 300 rpm idle speed range P ₅ : Engine There either rotating P _6: the actuator 26 is either in operation P _7: rotational speed NE is a predetermined value E ₃ (e.g. 4000 rpm) or more or P _8: or rotational speed NE is a predetermined value E ₂ (e.g., 3000 rpm) or P ₉ : Rotational speed NE is a predetermined value E ₁ (eg 2000 rpm) or more P ₁₀ : Throttle valve opening CV is a value TH ₀ (eg 40 °) or more P ₃₁ : Lubricating oil temperature T ₀ is a value T ₀₁ or more P ₃₂ : Is the cooling water temperature Tw equal to or higher than a predetermined value Tw ₁ ? And from these determination results, it is determined which of the following (I) to (V) the operating state of the engine corresponds to, and the cam surface Go to selection flow KSF.

(I) idle P ₁ by the throttle valve is fully closed, not depressed the clutch pedal P _2, P ₃ is the gear is in the neutral position, the rotational speed NE is in the idle speed range at P _4, when the condition is satisfied that, it is determined that the idle state, the process proceeds to set a flag Fpos to 1 at P ₁₁ to the cam surfaces selected flow KSF.

(II) Stop state Non-idle state (that is, the throttle valve is not fully closed at P ₁ ,
Or, the clutch pedal is depressed at P ₂ via P ₁ ,
If the gear is not in the neutral position at P ₃ via P ₁ -P ₂ or if the rotational speed NE is not in the idle speed range at P ₄ via P ₁ -P ₃ ) and the engine rotates at P _5. If not, it determines that the vehicle is in a stopped state, flag P ₁₃ F
Set pos to 0 and proceed to the cam surface selection flow KSF.

(III) the engine in P ₅ through the starting operation state P ₁ to P ₄ (non-idle state) is rotating, the actuator 26 is deactivated at P _6, it is detected by the oil temperature switch 44 in P ₃₁ Lubricating oil temperature T ₀ is a specified value
It is less than T ₀₁ , the cooling water temperature Tw detected by the water temperature switch 45 in P ₃₂ is less than the predetermined value Tw ₁ , and the rotation speed NE is 4 in P _7.
Is less than 000 rpm, when a 3000rpm speed NE at P _8, when the rotational speed NE at P ₉ is less than 2000 rpm, or P ₉
Even if the rotational speed NE is 2000 rpm or more, the throttle valve opening is set at P _10.
When CV is less than the predetermined value TH ₀ (for example, 40 °), it is determined that the vehicle has entered the starting operation state, the flag Fpos is set to 2 at P ₁₄ , and the process proceeds to the cam surface selection flow KSF.

(IV) when the rotational speed NE is 3000rpm or more traveling state P ₁ to P ₇ through P _8,
Alternatively, if the throttle valve opening CV is greater than or equal to the predetermined value TH ₀ at P ₁₀ through P _{1 to} P ₉ , it is determined that the vehicle is in the running state, and P ₁₅
Then, the flag Fpos is set to 3, and the process proceeds to the cam surface selection flow KSF.

When the rotational speed NE is 4000rpm or more for P ₇ via (V) high-speed running state P ₁ to P _6, it determines that the vehicle is in a high-speed running state, flag P ₁₆ F
Set pos to 4 and proceed to the cam surface selection flow KSF.

Incidentally, in the non-idle state, when the actuator 26 is operating in P ₆ , the process returns to P ₁ .

Here, the flags Fpos = 1 to 4 are set as described above, but when schematically shown, as shown in FIG. 7, mainly the engine speed NE and the throttle valve opening CV are set. The respective areas are set based on the relationship. In this case, throttle valve opening CV
In place of the above, it is possible to replace the ones indicating the load state of the engine such as the intake air amount and the intake negative pressure.

Next, to determine the flow KSF cam surface selected, set value of the flag Fpos at P ₁₂ and (0-4). That is, when Fpos = 4, go to P ₁₇ , when Fpos = 3, go to P ₁₈ , Fpos =
To P ₁₉ when a 2, the process proceeds respectively to the P ₂₀ when a FPOS = 1, the actuator 2 in P ₂₁ when a FPOS = 0
Stop rotation of 6. P ₁₇ to P ₂₀ in the set value of the flag Fpos determine the rotational position signal Vpos inputted through the A / D converter 42 from the potentiometer 41 attached to the lift control shaft 21 corresponding to the (1-4) To do. Here, this Vpos is set to be a predetermined value (6-1) corresponding to each cam surface 20a to 20f from the cam surface 20a having the largest lift amount to the cam surface 20f having the smallest lift amount in sequence. ing. That is, when the cam surface 20a is Vpos = 6, when the cam surface 20b is Vp
os = 5, and in the same manner, Vpos = 1 is set for the cam surface 20f.

When P ₁₇ in which Vpos corresponds to any one of 1 to 5 proceeds to P ₂₃ is set to 1 to flag Fth at P _22, Vpos is 6 (corresponding to the lift amount is greatest cam surface 20a) When is P
Proceed to ₂₁ to stop the rotation of the actuator 26. When P ₁₈ in which Vpos falls under any of 1 to 4 proceeds to P ₂₃ sets a flag Fth to 1 at P _24, when Vpos is 6 P
₂₅ proceeds flag Fth is set to 0 to P _23, also when Vpos is 5 stops rotation of the actuator 26 in the P _21. P
When the ₁₉ Vpos corresponds to any one of 1 to 3 proceeds to P ₂₃ is set to 1 to flag Fth at P _26, the flag Fth in P ₂₇ when under any Vpos is 5 or 6 Set to 0 and proceed to P _23. When Vpos is 4, the rotation of the actuator 26 is stopped at P ₂₁ . Further, when Vpos corresponds to any of 2 to 6 at P ₂₀ , the flag Fth is set to 0 at P _28.
It is set to proceed to P _23, also when Vpos is 1 stops the rotation of actuator 26 at P _21.

In P ₂₃ flag Fth is determined whether it is 0 or 1, and when the flag Fth is 0 rotated to the left in Figure 2 the actuator 26 (the drive shaft 26a) at P _29, the flag Fth
When is 1, the actuator 26 is rotated to the right with P ₃₀ .

Thus, for example, when the engine is in the idle state, and sets the flag Fpos to 1 at P _11, it is determined Vpos at P _20. At this time, Vpos is the cam surface 20 with the largest lift amount.
If it is 6 corresponding to a, the flag Fth is set to 0 at P ₂₈ , and the drive shaft 26a of the actuator 26 rotates leftward at P ₂₉ . Thus Vpos is sequentially changed 5,4,3,2 and Vpos becomes 1 (the most value lift amount corresponding to the small cam surface 20f), the drive shaft 26a of the actuator 26 in P ₂₁
Is stopped, and the required cam surface 24f is selected.

In this way, the control cam 20 has a cam surface with a small lift amount.
When the lever 15 comes into contact with the lever 15 at 20f, the end of the lever 15 on the intake / exhaust valve drive cam 11 side rises by swinging around the recess 15c as a fulcrum, and the lower surface of the lever 15 also retracts upward. Lever 15
The lower surface of the rocker arm 13 serves as a fulcrum F for transmitting the lift of the intake / exhaust valve drive cam 11 to the intake / exhaust valve 12, and this fulcrum F moves to the side away from the intake / exhaust valve 12. As a result, as shown by the curve D in FIG. 8, the lift amount is small, the valve opening timing is delayed, and the valve closing timing is advanced. In this state, both the lift amount and the operating angle are small, so that the friction is reduced and the combustion state is improved, and the fuel consumption can be greatly saved. Also, the noise generated by the valve mechanism is reduced, and the engine can be kept quiet.

Next, depress the clutch and start the vehicle.
_{At 14} , the flag Fpos is set to 2. At this time, V ₁₉
When it is determined s, since Vpos as described above has a 1 (value corresponding to the cam surfaces 20f), the flag Fth at P ₂₆ is set to 1. Thus, the drive shaft 26a of the actuator 26 in the P ₃₀ is sequentially rotated to the right, the Vpos is 4 P _19, rotation of the drive shaft 26a is selected predetermined cam surface 20c is stopped. Therefore, the underside of the lever 15 and the rocker arm
The contact fulcrum F with the rear surface of 13 moves to the intake / exhaust valve 12 side compared to when the cam surface 20f with the smallest lift amount is in contact with the lever 15. As a result, as shown by the curve C in FIG. 8, the lift amount becomes large and the operating angle becomes wide, so that the acceleration state can be smoothly shifted.

Next, while the vehicle is running, for example, the engine speed NE is 4000rp
When it becomes m or more, the flag Fpos is set to 4 in P ₁₆ . Then, when Vpos corresponds to any of 1 to 5 in P ₁₇ , the flag Fth is set to 1 in P ₂₂ , and the drive shaft 26a of the actuator 26 sequentially rotates to the right in P ₃₀ . Thereafter, when Vpos is 6, the actuator 2 with P ₂₁
The rotation of 6 is stopped and the cam surface 20a with the largest lift amount
Is selected. Therefore, as shown in FIG. 2, the lift control 20 causes the lever 15 to move on the cam surface 20a having the largest lift amount.
And the lever 15 is pushed down to the intake / exhaust valve drive cam 11 side most. For this reason, the lower surface of the lever 15 that is in fulcrum contact with the rear surface 13a of the rocker arm 13 also lowers, and the lift is transmitted to the intake / exhaust valve 12 while the fulcrum F moves to the intake / exhaust valve drive cam 11 side, and as shown in FIG. As shown by the curve A, the lift amount is large, the valve opening timing is advanced, and the valve closing timing is delayed. As a result, high filling efficiency can be ensured, so that the output of the engine can be improved.

Also, while the vehicle is running, for example, the engine speed NE is 3000
In the case of more than rpm flag Fpos at P ₁₅ is set to 3. Therefore, when Vpos is 5 at P ₁₈ , the rotation of the actuator 26 is stopped at P ₂₁ and the predetermined cam surface 20b is selected. As a result, the lift characteristic as shown by the curve B in FIG. 8 is obtained, and the high filling efficiency according to the traveling state can be secured.

In this way, the lift control cam 20 is rotated to rotate the cam surface 20.
By contacting any one of a to 20f with the lever 15, the lift characteristics of the intake / exhaust valve 12 can be finely changed stepwise according to the operating state of the engine.

On the other hand, the process proceeds to P ₃₁ through P ₁ to P _6, the lubricating oil temperature T ₀ is a predetermined value T
_When it is determined that the temperature is ₀₁ or higher, or even if the lubricating oil temperature T ₀ is less than T ₀₁ , proceed to P ₃₂ and set the cooling water temperature Tw.
When it is determined that is in a high temperature state that is equal to or higher than the predetermined value Tw _1, P
Sets a flag Fpos to 1 proceeds to ₁₁ proceed to the cam surfaces selected flow KSF. As a result, the required cam surface 20f with the minimum lift amount is selected as in the idle state. That is,
When the cam surface 20f is selected, the effective lift area of the intake / exhaust valve is small due to the small lift amount, and the effective intake / exhaust stroke is short due to the short valve opening period, so the intake / exhaust efficiency is reduced and the engine output Is reduced. As a result, the output of the engine is suppressed and the calorific value decreases, so the lubricating oil temperature T ₀ and the cooling water temperature Tw
It is possible to prevent problems such as engine burn-in and overheating.

Further, in this embodiment, the cam surface 20f having the smallest lift amount is selected when the engine temperature is high as described above, but when the determination of P ₃₁ or P ₃₂ is YES, the dotted line is shown in FIG. 6 (A). As shown in P ₁₄ , the flag Fpos may be set to 2 to select the cam surface 20e having the second smallest lift amount. That is, it is intended to secure a certain level of engine output even in a high oil temperature or high water temperature state.

<Effects of the Invention> As described above, according to the present invention, when the engine is in a high temperature state close to overheating, the characteristics of the intake / exhaust valve are maintained at the characteristics of a small lift amount. The effect is that the temperature is suppressed, the oil temperature and the water temperature are lowered, overheat is prevented, and problems such as engine scuffing and seizure can be avoided.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a vertical sectional view of a variable intake / exhaust valve lift mechanism showing an embodiment of the present invention, and FIG. 3 is a plan view of relevant parts of the same. FIG. 4 is an exploded perspective view of a portion of the lift control cam, FIG. 5 is a block diagram of a control circuit, FIGS. 6 (A) and 6 (B) are flowcharts of a control program, and FIG. , FIG. 8 is a diagram showing lift characteristics. 11 …… Intake / exhaust valve drive cam, 12 …… Intake / exhaust valve, 13 ……
Rocker arm, 15 …… Lever, 20 …… Lift control cam,
20a to 20f …… Cam surface, 21 …… Cam control shaft, 24 …… Torsion coil spring, 26 …… Actuator, 27 …… Control circuit, 30 …… CPU, 36 …… Rotation sensor, 37 …… Throttle valve Position sensor, 39 …… Neutral switch, 40 …… Clutch switch, 41 …… Potentiometer, 44 …… Oil temperature switch, 45 …… Water temperature switch

Claims (1)

[Claims] 1. An intake / exhaust valve having variable lift characteristics.
Exhaust valve lift variable mechanism, operating state detection means for detecting the operating state of the engine, control for switching control of the intake / exhaust valve lift variable mechanism so as to select a predetermined lift amount according to the region of the engine operating state In a variable valve lift control device including means, when the temperature of the engine exceeds a predetermined temperature that is set close to a high temperature state equivalent to overheating, the engine temperature detection means that detects the temperature state of the engine A valve lift variable control device comprising: high temperature control means for controlling the intake / exhaust valve variable mechanism so that the lift characteristic of the intake / exhaust valve is set to the maximum lift regardless of the state region. .