JP4003633B2 - Engine starter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine starter including a centrifugal clutch.
[0002]
[Prior art]
As a prior art, an internal combustion engine starting device described in Patent Document 1 is known.
The internal combustion engine starter includes a pulley that is attached to a rotation shaft on the engine side and a pulley that is attached to the rotation shaft of the starter motor. Type clutch).
The one-way clutch has an outer integrally provided with the pulley, an inner that is driven by the starter motor to rotate, a roller that is disposed between the outer and the inner, and the rotation of the starter motor is directed to the engine side. Only when transmitting (when starting the engine), the outer and the inner are locked via the roller, and the rotation of the inner is transmitted to the outer. After the engine is started, the roller is idled so that the outer and the inner are free, thereby interrupting the power transmission from the engine side to the starter motor side.
[0003]
[Patent Document 1]
Japanese Utility Model Publication No. 52-15631 [0004]
[Problems to be solved by the invention]
However, in the prior art disclosed in Patent Document 1 above, since the pulley on the engine side and the pulley on the starter motor side are coupled by a belt, the engine torque is always applied to the starter motor side pulley even after the engine is started. Communicated. As a result, until the roller is separated from the inner (while the roller is idling), wear occurs on the contact surface of the roller that contacts the outer peripheral surface of the inner. If this wear progresses, the shape and dimensions necessary for torque transmission at the time of engine start will not be established, resulting in a problem that torque transmission becomes impossible.
[0005]
In particular, the clutch shown in the above prior art is compared with a clutch employed in a gear meshing release type starter (a starter that engages a pinion gear with a ring gear to start the engine and then releases the pinion gear from the ring gear after the engine is started). Since the time that is turned by the engine is much longer (approximately 5000h VS 50h), it is extremely important to ensure the durability of the clutch.
The present invention has been made based on the above circumstances, and an object of the present invention is to provide an engine starter having a centrifugal clutch in which an outer always rotates (rotated by the engine) during engine rotation. It is to ensure durability.
[0006]
[Means for Solving the Problems]
(Invention of Claim 1)
The present invention is an engine starter in which a centrifugal clutch is disposed between a starter motor and an output member,
The centrifugal clutch has an inner driven by a starter motor to rotate, an outer rotating integrally with an output member, and a roller disposed between the inner and the outer, and the roller is accommodated on the inner periphery of the outer This is an outer cam type roller clutch that has a cam chamber that uses the engine rotation speed that maximizes the product of the surface pressure generated between the roller and the inner and the relative rotation speed of the roller and the inner. It is characterized by being set so as to be lower than the frequent engine speed.
[0007]
When the relative rotational speed (V) between the roller and the inner is constant, the wear of the roller increases as the surface pressure (P) generated between the roller and the inner increases. Further, if the surface pressure generated between the roller and the inner is constant, the surface pressure increases as the relative rotational speed between the roller and the inner increases.
However, since the centrifugal force acting on the roller increases as the engine speed increases, the surface pressure generated between the roller and the inner decreases, and becomes zero when the roller is separated from the inner. On the other hand, the relative rotational speed between the roller and the inner increases as the engine rotational speed increases.
[0008]
Accordingly, when the product of P and V is taken, a maximum value appears, so that it is understood that the wear of the roller is maximized at the engine speed at which the maximum value appears. Further, since PV value × time (frequency of use) ∝amount of wear, the engine rotation speed at the time when the wear of the roller is maximized (the PV value is maximized) is lower than the most frequently used engine rotation speed. If set in such a manner, the frequency of use of the engine when the PV value becomes maximum can be suppressed, so that the durability of the centrifugal clutch can be sufficiently ensured.
[0009]
(Invention of Claim 2)
The present invention is an engine starter in which a centrifugal clutch is disposed between a starter motor and an output member,
The centrifugal clutch has an inner that is driven by a starter motor to rotate, an outer that rotates integrally with an output member, and a roller that is disposed between the inner and the outer. The roller is accommodated on the inner periphery of the outer. This is an outer cam type roller clutch in which a cam chamber is formed. When the engine rotation speed when the roller is separated from the inner by centrifugal force after the engine is started is called the separation rotation speed, the separation rotation speed is set as the starter. It is characterized by being set higher than the no-load rotation speed of the motor.
[0010]
For example, if the rotational speed decreases due to a misfire after starting the engine, if the clutch separation rotational speed is lower than the no-load rotational speed of the starter motor, the clutch is engaged (the roller contacts the inner and idling stops. ), An excessive impact load is generated according to the difference between both rotation speeds.
On the other hand, if the separation rotational speed of the clutch is set higher than the no-load rotational speed of the starter motor, when the engine speed decreases and the clutch is connected after the engine misfires, the two are connected without any difference in rotational speed. Thus, an excessive impact load does not occur, and a smooth clutch connection is possible.
[0011]
(Invention of Claim 3)
The engine starter according to claim 1,
For the centrifugal clutch, when the engine rotation speed when the roller is separated from the inner by centrifugal force after the engine is started is called the separation rotation speed, the separation rotation speed is set higher than the no-load rotation speed of the starter motor. It is characterized by.
In this invention, the effect described in claim 1 (the durability of the centrifugal clutch can be ensured) and the effect described in claim 2 (excessive impact when the rotational speed is reduced due to engine misfire and the clutch is connected) Load is not generated).
[0012]
(Invention of Claim 4)
The engine starter according to any one of claims 1 to 3,
The output member is a starter pulley provided integrally with the outer,
The power transmission means is constituted by connecting a starter pulley and a crank pulley attached to the crankshaft by a belt.
In the present invention, since the outer clutch is integrated with the starter pulley, the centrifugal clutch can be arranged inside the starter pulley, so that the size of the entire apparatus can be reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows the relationship between the usage distribution of the engine speed and the clutch PV value.
As shown in FIG. 2, the engine starter of the present embodiment includes a starter motor 2 that generates a rotational force for starting the engine 1, and a bearing 4 (see FIG. 3) for the output shaft 3 of the starter motor 2. The starter pulley 5 is attached to the crankshaft 6 of the engine 1 by a belt 8. The starter pulley 5 is attached to the crankshaft 6 of the engine 1.
[0014]
The starter motor 2 is, for example, a known DC motor (or AC motor), and a built-in armature (not shown) is energized to generate a rotational force.
The output shaft 3 is connected to the rotation shaft (armature shaft) of the starter motor 2 via, for example, a planetary gear reduction device (not shown), and the rotation of the armature is reduced by the reduction device and transmitted.
A centrifugal clutch 9 is disposed between the output shaft 3 and the starter pulley 5 so that the rotational force of the engine 1 is not transmitted to the starter motor 2 (armature) after the engine 1 is started.
[0015]
As shown in FIG. 3, the centrifugal clutch 9 has an inner 9b and an outer 9c that are opposed to each other in the radial direction via a roller 9a, and a cam chamber 9d (see FIG. 3) that accommodates the roller 9a on the inner periphery of the outer 9c. 4) is an outer cam type roller clutch. The inner 9 b is fitted to the outer periphery of the output shaft 3 so as to be rotatable integrally with the output shaft 3, and is driven by the starter motor 2 when the engine 1 is started.
The outer 9c is provided integrally with the starter pulley 5, and is supported so as to be rotatable relative to the inner 9b by a pair of bearings 4 disposed on both axial sides of the roller 9a (left and right sides in FIG. 3). .
[0016]
The roller 9a is disposed in a wedge-shaped space formed between the inclined surface of the cam chamber 9d and the outer peripheral surface of the inner 9b, and is urged by a spring 9e (see FIG. 3) in a direction in which the wedge-shaped space is narrowed. ing.
In the centrifugal clutch 9, when the inner 9b is driven by the starter motor 2 and rotates integrally with the output shaft 3, the inner 9b and the outer 9c are locked via the roller 9a as shown in FIG. Thus, the rotation of the inner 9b is transmitted to the outer 9c. The rotation of the outer 9 c is transmitted from the starter pulley 5 to the crank pulley 7 by belt transmission, and rotates the crankshaft 6 of the engine 1.
[0017]
When the engine 1 is cranked by the rotation of the crankshaft 6 and the rotation speed of the outer 9c exceeds the rotation speed of the inner 9b (becomes an overrun state), as shown in FIG. 4B, the roller 9a is moved to the inner 9b. As a result, the outer 9c and the inner 9b become free and the power transmission from the outer 9c to the inner 9b is interrupted.
Thereafter, when the engine rotational speed increases and the rotational speed difference between the outer 9c and the inner 9b increases, the roller 9a is separated from the inner 9b by the centrifugal force as shown in FIG. 4C (the roller 9a and the inner 9b). 9b is completely non-contact). The engine rotation speed when the roller 9a separates from the inner 9b is referred to as a separation rotation speed.
[0018]
Here, after the engine 1 is cranked, the roller 9a and the inner 9b are not completely in non-contact (the roller 9a is not in contact) while the roller 9a is idling (the state shown in FIG. 4B). Wears on the contact surface of the roller 9a that contacts the outer peripheral surface of the inner 9b.
The wear of the roller 9a can be represented by the product of the surface pressure (P) generated between the roller 9a and the inner 9b and the rotational speed difference (relative rotational speed: V) between the roller 9a and the inner 9b. By multiplying the PV value by the total time of the overrun state (the lifetime of the vehicle in which the roller 9a idles), a numerical value that directly affects the amount of wear of the roller 9a can be obtained.
[0019]
By the way, as shown in FIG. 5A, the surface pressure (P) generated between the roller 9a and the inner 9b decreases as the engine speed increases and the roller 9a is separated from the inner 9b. 0 (separation rotation speed). On the other hand, the relative rotational speed (V) between the roller 9a and the inner 9b increases as the engine rotational speed increases as shown in FIG. 5 (b). As a result, the PV value has a maximum value as shown in FIG. 5C, and it can be seen that the wear of the roller 9a is the largest at the engine speed at which the maximum value appears.
[0020]
Therefore, in order to reduce the amount of wear of the roller 9a, the frequency of use of the engine speed when the PV value becomes maximum may be reduced. The engine rotation speed at which the PV value becomes maximum increases as the separation rotation speed of the centrifugal clutch 9 increases. That is, when the separation rotational speed is set to be high, generally the load of the spring 9e that urges the roller 9a is increased (or the weight of the roller 9a is increased), so that it occurs between the roller 9a and the inner 9b. The surface pressure (P) increases and the PV value itself increases. In addition, since the separation rotation speed is increased, the time during which the roller 9a is idling also becomes longer, so that the engine rotation speed when the PV value is maximized is increased as shown in FIG.
[0021]
As a result, if the separation rotational speed of the centrifugal clutch 9 is set high, the wear amount of the roller 9a is greatly increased by that amount, so that the life of the centrifugal clutch 9 is shortened. Therefore, as shown in FIG. 1, the centrifugal clutch 9 of the present embodiment has the highest engine rotation speed (for example, about 1000 rpm) when the wear of the roller 9a is maximum (the PV value is maximum). It is designed to be lower than a high engine speed (for example, about 1800 rpm). In addition, the graph A shown in the figure represents the PV value, and the graph B represents the usage distribution of the engine speed (rpm). Further, the most frequently used engine rotation speed refers to an engine rotation speed that is most frequently used (highly used, long time) in the engine 1 mounted on the vehicle.
[0022]
(Effects of the first embodiment)
The centrifugal clutch 9 described above is designed so that the engine rotation speed when the PV value becomes maximum is lower than the engine rotation speed that is most frequently used, so that the PV value itself can be lowered and the vehicle travels. The frequency of use at the time can be reduced (the total time during which the roller 9a idles can be shortened). As a result, the amount of wear of the roller 9a can be reduced, so that the durability of the centrifugal clutch 9 can be sufficiently ensured.
[0023]
(Second embodiment)
In the centrifugal clutch 9 of this embodiment, the separation rotational speed is set higher than the no-load rotational speed of the starter motor 2.
For example, after the engine 1 is started, when the rotational speed is suddenly decreased due to misfire or the like, and the separation rotational speed of the centrifugal clutch 9 is lower than the no-load rotational speed of the starter motor 2, the clutch is engaged (roller When 9a comes into contact with the inner 9b and idling is stopped), an excessive impact load is applied to the starter motor 2 in accordance with the difference between both rotational speeds (see FIG. 7A).
[0024]
On the other hand, if the separation rotation speed of the centrifugal clutch 9 is set higher than the no-load rotation speed of the starter motor 2, the no-load rotation speed of the starter motor 2 when the rotation speed rapidly decreases due to misfire of the engine 1 Since the clutch can be engaged, an excessive impact load does not occur when the clutch is engaged, and a smooth clutch connection is possible (see FIG. 7B).
As described above, the separation rotational speed of the centrifugal clutch 9 can be set by the load of the spring 9e that urges the roller 9a, the weight of the roller 9a, the wedge angle of the cam chamber 9d, or the like.
[0025]
(Third embodiment)
The centrifugal clutch 9 of the present embodiment is configured by combining the first embodiment and the second embodiment. That is, the engine rotation speed when the PV value is maximized is designed to be lower than the most frequently used engine rotation speed, and the separation rotation speed is set higher than the no-load rotation speed of the starter motor 2. .
Thereby, the centrifugal clutch 9 having both the effect of the first embodiment and the effect of the second embodiment can be realized.
[Brief description of the drawings]
FIG. 1 is a characteristic diagram showing a relationship between a distribution of use of engine rotation speed and a clutch PV value.
FIG. 2 is a view showing an example of use of an engine starter.
FIG. 3 is a sectional view showing a configuration of a centrifugal clutch.
FIG. 4 is an operation explanatory view of a centrifugal clutch.
FIG. 5 is an explanatory diagram of a PV value of a centrifugal clutch.
FIG. 6 is a characteristic diagram showing a relationship between a PV value and a separation rotation speed.
FIG. 7 is a drawing showing the relationship between the separation rotational speed and the no-load rotational speed of the starter motor.
[Explanation of symbols]
1 Engine 2 Starter motor 5 Starter pulley (output member)
6 Crankshaft 7 Crank pulley 8 Belt (power transmission means)
9 Centrifugal clutch 9a Roller 9b Inner 9c Outer

Claims (4)

A starter motor that generates rotational force;
An output member for outputting the rotation of the starter motor;
A power transmission means for constantly connecting the output member and the crankshaft of the engine to transmit the rotation of the output member to the crankshaft;
An engine starter in which a centrifugal clutch that interrupts power transmission from the output member side to the starter motor side is disposed between the starter motor and the output member,
The centrifugal clutch includes an inner driven by the starter motor to rotate, an outer rotating integrally with the output member, and a roller disposed between the inner and the outer, An outer cam type roller clutch in which a cam chamber for accommodating the roller is formed on the inner periphery;
The engine rotation speed at which the product of the surface pressure generated between the roller and the inner and the relative rotation speed between the roller and the inner is maximized is set to be lower than the most frequently used engine rotation speed. An engine starter characterized by that. A starter motor that generates rotational force;
An output member for outputting the rotation of the starter motor;
A power transmission means for constantly connecting the output member and the crankshaft of the engine to transmit the rotation of the output member to the crankshaft;
An engine starter in which a centrifugal clutch that interrupts power transmission from the output member side to the starter motor side is disposed between the starter motor and the output member,
The centrifugal clutch includes an inner driven by the starter motor to rotate, an outer rotating integrally with the output member, and a roller disposed between the inner and the outer, An outer cam type roller clutch in which a cam chamber for accommodating the roller is formed on the inner periphery;
When the engine rotation speed when the roller is separated from the inner by centrifugal force after the engine is started is called a separation rotation speed, the separation rotation speed is set higher than the no-load rotation speed of the starter motor. A characteristic engine starting device. The engine starter according to claim 1,
When the engine rotation speed when the roller is separated from the inner by centrifugal force after the engine is started is referred to as a separation rotation speed, the separation rotation speed is referred to as a no-load rotation speed of the starter motor. An engine starter characterized by being set higher. The engine starter according to any one of claims 1 to 3,
The output member is a starter pulley provided integrally with the outer;
The engine starter characterized in that the power transmission means is configured by connecting the starter pulley and a crank pulley attached to the crankshaft by a belt.

Images