JPH08326854A - Tension adjusting device for endless transmission belt in internal combustion engine - Google Patents

Abstract

PURPOSE: To provide a tension adjusting device for an endless transmission belt in an internal combustion engine, which can appropriately operate a tensioner always by precisely adjusting the tension of the endless belt in accordance with an actual variation in the temperature (actual variation in tension) of the engine body. CONSTITUTION: A control means C for automatically adjusting the tension to be applied to an endless transmission belt B, is composed of an oil temperature sensor S for detecting a temperature of lubrication oil in an internal combustion engine E, and a control device CPU for setting a desired control value in accordance with a temperature of lubrication oil detected by the oil temperature sensor S so as to control the operation of a tension changing device A in accordance with the desired control value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensioner which is in contact with an endless transmission belt provided in an internal combustion engine, and a tensioner device which has a tension changing device capable of changing the tension to be applied from the tensioner to the endless transmission belt. And a control means for automatically adjusting the tension according to the state,
The present invention relates to a tension adjusting device for an endless transmission band in an internal combustion engine.

[0002]

2. Description of the Related Art The above-mentioned tension adjusting device has been variously used in the past for the purpose of accurate transmission of power by suppressing fluctuations in belt tension due to changes in engine operating conditions, improvement of life due to stable belt tension, reduction of transmission noise, and the like. Proposed.

Of these, the one that automatically adjusts the transmission band tension in accordance with the engine temperature is intended to cope with an increase in the axial distance between the driven wheels and the driven wheels (and hence an increase in tension) due to the thermal expansion of the engine body. However, the engine temperature detection target of the conventional tension adjusting device of this type is limited to the cooling water temperature of the internal combustion engine (for example, see Japanese Utility Model Laid-Open No. 60-19850) or the engine ambient temperature.

[0004]

Generally, the upper limit temperature of the cooling water temperature of the internal combustion engine is set to be constant, and the cooling system temperature of the cooling system is set so that the water temperature does not exceed the upper limit temperature even during continuous high rotation and high load operation of the internal combustion engine. The performance is prescribed, and during these operations, the temperature of the engine body further rises while the lubricating oil temperature rises, even after the cooling water temperature reaches the upper limit near its upper limit as shown in FIG. As a result, the thermal expansion of the engine body further progresses, and the axial distance between the driven and driven wheels further increases as the thermal expansion progresses. For this reason, in the structure that automatically adjusts the transmission band tension according to the cooling water temperature, the engine body temperature accompanying high rotation and high load operation becomes high when the cooling water temperature rises and the tension adjustment is stopped. There is a problem that the tension increases due to the further increase of

On the contrary, when the engine is operated from a low temperature in a cold region or the like, especially in the early stage of the operation, the engine cooling water mainly circulates around the combustion chamber and the cylinder sleeve and is quickly warmed. As shown in FIG. 6, the cooling water temperature rises faster than the engine body temperature rise, that is, the change of the cooling water temperature slightly deviates from the temperature change of the entire engine body.

On the other hand, the ambient temperature of the engine is very susceptible to the influence of the outside air temperature, and therefore may deviate from the temperature of the main body of the engine, which is hardly influenced by the ambient temperature.

Therefore, if the tension is adjusted according to the temperature of the cooling water or the temperature of the engine atmosphere, it is not possible to accurately respond to the actual temperature change of the engine body (hence, the actual tension change), and the proper operation of the tensioner can be obtained. Absent.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tension adjusting device for an endless power transmission band in an internal combustion engine, which can solve the above problems of the conventional device.

[0009]

In order to achieve the above object, the present invention provides a tensioner in contact with an endless transmission band provided in an internal combustion engine, and a tension change capable of changing the tension to be applied from the tensioner to the endless transmission band. A tensioner device having a device, and a tension adjusting device for an endless transmission band in an internal combustion engine, comprising: a tension adjusting device for automatically adjusting the tension according to an engine operating state. An oil temperature sensor capable of detecting an oil temperature, a control device that sets a control target value according to the lubricating oil temperature detected by the oil temperature sensor, and controls the operation of the tension changing device based on this target value. It is characterized by having.

[0010]

[Operation] According to the above characteristics, the control device sets the control target value according to the lubricating oil temperature detected by the oil temperature sensor,
The operation of the tension changing device is controlled based on this target value.

By the way, while the temperature rise of the cooling water of the internal combustion engine reaches a peak at the set upper limit temperature, the temperature of the lubricating oil rises in accordance with the further rise of the temperature of the engine body, and the temperature of the cooling water is mainly the temperature of the internal combustion engine. In contrast to the temperature change around the combustion system, the lubricating oil temperature has a substantially linear relationship with the temperature change of the entire engine body, and the ambient temperature of the engine is easily affected by the outside air temperature. Is not easily affected by the outside temperature. Therefore, by setting the control target value for tension adjustment according to the lubricating oil temperature, the tension adjustment can be performed extremely accurately in response to the actual temperature change of the engine body (thus the actual tension change).

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall side view showing an outline of a first embodiment of the present invention, FIG. 2A is a graph showing a change in axial distance between a driven wheel and a driven wheel with respect to a temperature change of lubricating oil, and FIG.
FIG. 3 is a graph showing the belt average tension with respect to the temperature change of the lubricating oil, and FIG. 3 shows the setting mode of the control target value (advancing / retreating displacement amount of the tension pulley) of the actuator with respect to the temperature change of the lubricating oil. Is linear control,
(2) shows stepwise control, and (3) shows curvilinear control. FIG. 4 shows the outline of the second embodiment of the present invention.
FIG. 2 is an overall side view similar to FIG. 1.

First, in FIG. 1 showing a first embodiment, an engine body 1 of an internal combustion engine E has a cylinder block 2, a cylinder head 3 superposed on the cylinder block 2, and an open lower end of the cylinder block 2. The oil pan 4 is formed of a closed dish-shaped oil pan 4, and a predetermined amount of lubricating oil O is stored in the oil pan 4 for cooling and lubricating the sliding parts, the bearing parts, and the like in the engine body 1. The lubricating oil is forcibly circulated in the sliding portion and the bearing portion in the engine body 1 by the pump action of an oil pump (not shown) that rotates in conjunction with the crankshaft 5, and then returned to the oil pan 4. Be done. An oil temperature sensor S for detecting the temperature of the stored lubricating oil, that is, the lubricating oil inside the engine body is mounted on the peripheral wall of the oil pan 4, and the oil temperature sensor S keeps the temperature of the lubricating oil during engine operation. A corresponding detection signal is output to the control device CPU described later.

On the side surface of the engine body 1, a crank pulley 6 as a driving wheel connected to a crank shaft 5 and a pair of cam pulleys 8 as driven wheels respectively connected to a pair of valve operating cam shafts 7, 8 and a freely rotatable idle pulley 9
And a timing belt B as an endless transmission belt suspended between these pulleys 6, 8 and 9, and a winding type timing transmission mechanism I is arranged. It rotates in the indicated direction R (FIG. 1). The transmission mechanism I is provided with a tensioner device T for automatically adjusting the tension of the belt B on the loose side of the timing belt B, specifically, between the crank pulley 6 and the idle pulley 9.

The tensioner device T includes a tension pulley 10 as a tensioner that contacts the timing belt B.
And an actuator A for moving the tension pulley 10 forward and backward with respect to the timing belt B. The actuator A constitutes a tension changing device capable of changing the tension applied to the belt B from the tension pulley 10. To do. In addition, the tensioner device T is provided with a tensioning force so that the timing belt B can be provided with a necessary minimum tension so that the transmission ability is not lost even at the time of maximum belt loosening due to low temperature or stretching of the belt. A means for applying a predetermined initial pressing force to the pulley 10 is attached. As the means for applying the initial pushing force, for example, a mechanical spring can be used or the actuator A itself can be used. Particularly, in the latter case, the initial pushing force is tensioned after the engine is turned on and before starting. Pulley 10
Actuator A is actuated in order to apply

The actuator A has a support arm 11 that rotatably supports a tension pulley 10 at its tip.
And an actuator body 12 that supports the support arm 11 so as to be movable back and forth with respect to the timing belt B. The actuator body 12 is integrally attached to the side surface of the engine body 1. In the actuator body 11,
It is well known that the support arm 11 (and therefore the tension pulley 10) can be moved back and forth with respect to the timing belt B in response to a control current output from a control device CPU including a central processing unit installed in a proper place outside the engine body 1. An electric drive unit is built in.

An oil temperature sensor S is connected to the control unit CPU, and a detection signal corresponding to the lubricating oil temperature output from the sensor S is continuously input to the control unit CPU during engine operation. Then, the control device CPU sets a control target value according to the lubricating oil temperature detected by the oil temperature sensor S as described later, and the actuator A is set based on this target value.
Controls the amount of forward / backward displacement of. The control device C and the oil temperature sensor S cooperate with each other to form a control means C for automatically adjusting the tension to be applied from the tension pulley 10 to the timing belt B.

Next, the operation of the above embodiment will be described.
In the engine operating state, the temperature of the engine body 1 and the lubricating oil temperature in the oil pan 4 always change in a substantially linear relationship. Therefore, when the internal combustion engine E is operating at high rotation speed and high load, the lubricating oil temperature rises as the engine body temperature rises and the engine body rises even after the cooling water temperature reaches the upper limit temperature and reaches a ceiling as shown in FIG. The thermal expansion of No. 1 progresses, and the inter-axial distance between the crank pulley 6 and the cam pulley 8 increases as shown in FIG. Therefore, in order to keep the tension that the tensioner device T should apply to the timing belt B substantially constant, that is, within the set range, as compared with the tension adjusted by the fixed tensioner, as shown in FIG. It should be controlled so that the oil tends to be tense at low temperatures and loose at high temperatures.

Therefore, the displacement amount by which the actuator A should move the tension pulley 10 back and forth toward the belt B side according to the temperature change of the lubricating oil is basically the tension pulley 10 belt as the lubricating oil temperature increases as shown in FIG. It is decided to move to the side where the tension is relaxed (that is, retreat with respect to the belt B). In the illustrated example, the control target set in advance corresponding to the lubricating oil temperature (that is, the detection signal from the oil temperature sensor S) so that the tension of the timing belt B is always adjusted to be substantially constant regardless of the temperature change of the lubricating oil. The operation amount of the actuator A as a value (that is, the amount of forward / backward displacement of the tension pulley 10) is stored in advance in the storage unit of the control device CPU. Then, the control device CPU calls the control target value from the storage unit according to the detection signal from the oil temperature sensor S, and outputs the control current according to the called control target value to the drive unit of the actuator A, thereby The actuator A can be used to move the tension pulley 10 forward and backward according to the temperature of the lubricating oil, and thus the tension of the timing belt B is constantly adjusted to be substantially constant regardless of the temperature change of the lubricating oil.

As a mode of setting the control target value with respect to the temperature change of the lubricating oil, for example, a linear control with a constant downward slope as in (1) of FIG. 3 and a stepwise control as in (2) are performed. Either the control or the curvilinear control as in (3) may be selected, and any one of them may be appropriately combined.

By the way, the rise in the cooling water temperature of the internal combustion engine E reaches a ceiling at the set upper limit temperature, whereas the lubricating oil temperature rises in accordance with the further rise in the engine body temperature, and the cooling water temperature is mainly the internal combustion engine. E shows the temperature change around the combustion system, whereas the lubricating oil temperature always has a substantially linear relationship with the temperature change of the entire engine body 1, and the engine atmosphere temperature is easily influenced by the outside air temperature. Therefore, the lubricating oil temperature has the characteristic that it is not easily affected by the outside air temperature. Therefore, by setting the control target value for tension adjustment according to such a temperature change of the lubricating oil, it is possible to perform the tension adjustment extremely accurately corresponding to the actual engine body temperature (hence the actual tension change). It will be possible.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, in addition to the oil temperature sensor S, a tension sensor S'for detecting the tension of the timing belt B is connected to the control device CPU. As the tension sensor S ′, for example, a known tension sensor (that is, a strain gauge) that can detect the reaction force received by the tensioner device T from the timing belt B from the strain of the support arm 11 or the strain of the support shaft of the tension pulley 10 is used. It is possible,
Further, particularly when the electric drive unit built in the actuator A has a structure using a motor, a sensor capable of detecting the reaction force by a change in the load current of the motor may be used.

In the control unit CPU of this embodiment,
Each time the internal combustion engine E is started, the tension sensor S ′ is
The control current value set based on the detection signal is output to the drive unit of the actuator A, and the control current value is the actual tension at the time of starting the initial tension that the tensioner device T should apply to the timing belt B. It is set so that it can always be controlled to be substantially constant irrespective of variations in the tension.

In the internal combustion engine E, variations in the axial distance between the pulleys in the engine body, variations in the length of the belt itself as an endless transmission band, variations in the mounting position of the tensioner device, etc. Although the initial tension of the belt may vary at the time of starting, according to the structure of the present embodiment, each time the internal combustion engine E is started,
The control device CPU can output the control current set based on the detection signal of the tension sensor S ′ to the drive unit of the actuator A to control the initial tension to be substantially constant (that is, absorb the variation in the initial tension). Therefore, there is an advantage that the tension adjustment control according to the change in the oil temperature as described above after the start can be performed more accurately.

Further, particularly when the endless transmission belt is a timing belt, it depends on the position where the valve operating cam is stationary when the engine is stopped, that is, the relative position of the nose of the valve operating cam to the cam follower. , A part of the belt B that is in contact with the tensioner device T may be in a tensioned or loosened state, but by using the tension sensor S ′ and setting the initial tension appropriately (every time the engine is restarted). , Better control can be done.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments and various embodiments can be made within the scope of the present invention. For example, the position of the tension pulley may be on the driven side (that is, the loose side) of the timing belt as in the above embodiment, or on the drive side (that is, the tension side), and in the case of a multi-axis layout, it may be placed between any pulleys. May be. Although the oil temperature sensor is adapted to detect the lubricating oil temperature in the oil pan in the above embodiment,
If you can directly detect the lubricating oil temperature, regardless of the installation position,
For example, an oil temperature sensor may be installed in the cylinder block around the main gallery part to detect the oil temperature in the main gallery part in the middle of the lubricating oil passage formed in the cylinder block. Further, although the timing belt is shown as the endless power transmission belt in the above-mentioned embodiment, it may be an accessory driving belt other than the timing belt, and may be a timing chain or an accessory driving chain.

[0027]

As described above, according to the present invention, the control target value is set according to the lubricating oil temperature detected by the oil temperature sensor, and the operation of the tension changing device is controlled based on this target value. As a result, the tension of the endless transmission band can be automatically adjusted according to the temperature of the lubricating oil, which rises and changes in a substantially linear relationship according to the temperature rise of the entire engine body, and is not easily affected by the outside air temperature. Since the tension can be adjusted accurately in accordance with the actual temperature change of the engine body (and therefore the actual tension change), the tensioner can always be properly operated.

[Brief description of drawings]

FIG. 1 is an overall side view showing an outline of a first embodiment of the present invention.

FIG. 2A is a graph showing a change in the axial distance between the driven wheel and a driven wheel with respect to a change in the temperature of the lubricating oil, and FIG. 2B is a graph showing an average belt tension with respect to a change in the temperature of the lubricating oil.

FIG. 3 is a diagram showing a manner of setting an actuator control target value (advancing / retreating displacement of a tension pulley) with respect to a change in lubricating oil temperature, where (1) is linear control and (2) is stepwise control. And (3) shows curvilinear control, respectively.

FIG. 4 is an overall side view similar to FIG. 1, showing an outline of a second embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the engine body temperature, the cooling water temperature, and the lubricating oil temperature at the time of high engine speed and high load operation.

FIG. 6 is a graph showing changes over time in engine body temperature, cooling water temperature, and lubricating oil temperature during operation from low temperatures in cold regions and the like.

[Explanation of symbols]

A: Actuator as tension adjusting device B: Timing belt as endless transmission band C: Control means CPU: Control Device S ... Oil temperature sensor T ... Tensioner device 1 ... Engine body 4 ... Oil pan 10 ... .... Tension pulleys as tensioners

Claims (1)

[Claims] 1. A tensioner (10) in contact with an endless transmission band (B) provided in an internal combustion engine (E), and a tension change capable of changing the tension to be applied from the tensioner (10) to the endless transmission band (B). A tensioner device (T) having a device (A), and a control means (C) for automatically adjusting the tension according to an engine operating state, in a tension adjusting device for an endless transmission band in an internal combustion engine, The control means (C) is an oil temperature sensor (S) capable of detecting the lubricating oil temperature of the internal combustion engine (E), and the oil temperature sensor (S).
Set the control target value according to the lubricating oil temperature detected in
A tension adjusting device for an endless transmission band in an internal combustion engine, comprising: a control device (CPU) that controls the operation of the tension changing device (A) based on the target value.