JPS5815653B2 - Overload buffer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overload buffer device in a variable speed device using, for example, a wet multi-plate clutch.

Conventionally, in a variable speed device using a wet multi-disc clutch, the rotation speed of the output shaft is maintained at a constant value, and the output -
As shown in FIG. 1, the input shaft 2 can be freely rotated by the force of the body 1 of the variable speed device via a bearing (not shown) to buffer the excessive load torque applied to the input shaft. At the same time, the output shaft 4 is rotatably mounted on the body 1 through the bearings 3, and the tips of the input shaft 2 and the output shaft 4 are connected inside the body 1 with a gap 5 therebetween. A large number of friction plates 6 are fixed to the outer peripheral surface of the input shaft 2 at appropriate intervals, and a large number of friction plates 7 integral with the output shaft 4 are slid into the gaps between these friction plates 6. A pressure ring 8 which is freely fitted and presses one end surface of the friction plate 7 to provide frictional resistance to the sliding surfaces of each of the friction plates 6 and 7, and a supply pressure fluid passage 9 which supplies the operating pressure thereof. A friction plate provided on the output shaft side and further pushing the suppression ring 8 automatically adjusts the working pressure of the suppression fluid to maintain the rotational speed of the output shaft 4 at an arbitrary constant speed and prevent excessive load torque of the output shaft 4. There is one in which a centrifugal speed control drive mechanism 10 for buffering the input shaft 2 is provided on the output shaft 4 side.

This centrifugal speed control drive mechanism 10 includes a passage 28 provided with a centrifugal speed control valve 11 on the outer circumferential surface of the large diameter portion 4a of the output shaft 4 via a throttle resistor 22 in the supply pressure fluid passage 9.
It was installed facing the centrifugal speed control valve 11.
A governor weight 13 that can move forward and backward in the radial direction is fluid-tightly fitted inside the valve body 12, and the passage 28 is opened at the inner end of the governor weight 13, and the passage 28 is opened at the outer end of the governor weight 13. A passage 14 for a control pressure fluid that presses the governor weight 13 inward is opened, and a port 15 is further provided on the side wall of the valve body 12 to be opened and closed by the governor weight 13 to throttle and adjust the outflow resistance of the friction plate suppression fluid. Control pressure fluid is supplied to the passage 14 through a passage 16 bored inside the output shaft 4 .

Note that when supplying pressure fluid to the bullet path 9 and the passage 16 from the outside, the supply hole 17° 17 of the body 1 is replaced with a groove 19, 1 which is annularly bored in the outer peripheral surface of the intervening ring 18.
If the through holes 21 and 21 of the intervening rings 18 and 20 are communicated with the passages 9 and 16, pressure fluid can be constantly supplied to the output shaft during rotation.

Next, the operation of the above-mentioned general centrifugal speed control drive mechanism 10 will be explained based on the graphs shown in FIGS. 2 to 4.

Here, the fluid pressure in the passage 9 is the supply pressure P5, and the fluid pressure acting on the suppression ring 8 through the restriction resistor 22 in the passage 9 is the operating pressure Pa1, the fluid pressure P in the suppressing fluid passage 14.16.

Furthermore, when the output shaft rotates, the centrifugal force acting on the governor weight 13 of the centrifugal speed control valve 11 is converted into pressure, and the centrifugal force equivalent pressure Pω is defined as the pressure.

At this time, considering various pressures acting on the governor weight 13, equation P is obtained.

=Pa+Pω holds true. Here, the control pressure P is necessary to transmit a constant torque T to the output shaft 4 when the rotational speed of the output shaft 4 is in the range from 15 Orpm to 150 Orpm.

, the operating pressure Pa1 and the centrifugal force equivalent pressure P2 are respectively illustrated based on the above equations.

Note that the control pressure actually supplied is a constant pressure P regardless of the rotation speed.

0, and 1500 rpm is the rotational speed of the input shaft 2, and at this time the output shaft 4 is completely connected to the input shaft 2.

Now, in Fig. 2, the normal rotational speed N1 of the output shaft 4
Assuming that the rotational speed N2 changes to a smaller rotational speed N2 for some reason, the operation of the centrifugal speed control drive mechanism 10 to maintain the rotational speed of the output shaft 4 at a constant value will be explained.

Here, the torque T applied to the output shaft 4 and the control pressure PCo=
Pc1 is assumed to be constant.

At this time, the control pressure Pc1 of the rotation speed N1 and the rotation speed N2
The differential pressure P between the control pressure PC2 and the control pressure PC2 required to transmit the torque T.

1-P (2 further hangs on the outer end surface of the governor weight 13, pushes the governor weight 13 inward, and increases the outflow resistance of the opening 15.

Therefore, the working pressure Pa□' of the friction plate suppressing fluid applied to the suppressing ring 8 is P lower than the working pressure Pa2 required to transmit the torque T at this time.

1-Pc2, the frictional resistance of the sliding surfaces of the friction plates 6.7 increases, the torque transmitted to the output shaft 4 is increased, the rotational speed of the output shaft 4 is increased, and the rotational speed is stabilized at N1.

Conversely, if the rotational speed of the output shaft 4 increases from normal,
It stabilizes to its original state using the opposite principle.

The above is an explanation of the constant speed control operating mechanism of the centrifugal speed control valve.

Next, based on FIG. 3, we will discuss the buffering effect of the centrifugal speed control drive mechanism 10, assuming a case where an excessive load is suddenly applied to the output shaft 4 compared to the torque T transmitted to the output shaft 4 under normal conditions. explain.

At this time, the torque T transmitted to the output shaft 4 is insufficient, and the sliding of each of the friction plates 6 and 7 increases, and a buffering effect against the impact load appears, but normally the rotational speed of the output shaft 4 increases. As the governor weight 13 decreases,
The centrifugal force applied to the output shaft 4 decreases, the governor weight 13 moves inward, increases the operating pressure of the friction plate suppression fluid, and the output shaft 4
The transmission torque is increased to transmit the load.

When the operating pressure Pa' required to transmit this load V changes as shown in the figure, the centrifugal force equivalent pressure Pω' applied to the governor weight 13 is expressed as PCo-Pa', which is illustrated in FIG. It becomes like this.

Therefore, the rotational speed of the output shaft 4 decreases to a rotational speed N3 at which the load T' can be transmitted.

However, at this rotational speed N3, for example, the supply pressure P supplied to the passage 9 is the control pressure P as shown in the figure.

If it is set smaller than 0, the operating pressure Pa' is obtained from this supply pressure Ps via the throttling resistor 22, so it cannot be greater than the supply pressure PS, so actually at this rotation speed N3. The operating pressure "a3" required to transmit the load V cannot be obtained.

Therefore, the rotation of the output shaft 4 is stopped, and a buffering effect against the load T' can be obtained.

In this way, the centrifugal speed control drive mechanism 10 has the function of maintaining the rotational speed of the output shaft 4 at an arbitrary constant value and the operation pressure P.
This has the effect of buffering the excessive load applied to the output shaft 4 from reaching the input shaft 2 in a low speed range where a is close to the supply pressure Ps.

By the way, in the high speed range, the working pressure Pa required for equal torque transmission decreases as the rotation speed increases, and the -force and supply pressure PS need to have a margin to match the maximum Pa value in the low speed range. In the high speed range, the operating pressure Pa and supply pressure P8
The difference is getting bigger.

Therefore, as mentioned above, the increase in the required operating pressure due to overload does not exceed the supply pressure Ps, and as a result, the rotation of the output shaft does not stop, and the overload continues as it is on the input shaft 2.
, so no buffering effect can be obtained.

Furthermore, regarding the operation when the clutch is fully engaged, the actual control pressure in the vicinity of the clutch fully engaged due to oil pressure adjustment becomes a value larger than the necessary control pressure Po due to, for example, over-insertion of the operating lever.

Therefore, when the input shaft 2 and the output shaft 4 are completely coupled, that is, at 1500 rpm in this case, if a higher control pressure P is set as shown in FIG.
In the high speed range, the operating pressure Pa'' is represented by the value Pc''-Pω.

As shown in Fig. 4, the torque T'' transmitted by this operating pressure Pa' increases rapidly around 1500 rpm, and this is three to four times the rated torque T at the control pressure Pa. Equivalent to.

Therefore, when the clutch is fully engaged, even if an excessive load of 3 to 4 times the rated torque T of the output shaft 4 is applied, the load will not be buffered and will be applied to the input shaft 2, causing the input shaft side prime mover and this variable speed device to It may also cause damage.

In this way, when fully coupled, a slight setting error in the control pressure will cause a sudden increase in the transmitted torque, so great care must be taken.

Also in that case, there is no certainty that an appropriate control pressure has been set.

The present invention aims to improve these points, and by increasing the operating pressure P8 of the friction plate suppression fluid adjusted by the centrifugal speed control valve to the supply pressure Ps due to overload, the transmitted torque increases from T to T''. As a safety measure to prevent the increasing danger, the operating pressure Pa''', which is separate from the centrifugal speed control valve and is slightly higher than the above operating pressure Pa, is provided.
By installing a dump valve on the output shaft side that is adjusted to maintain the
The operating pressure of the friction plate suppression fluid is adjusted by a centrifugal speed control valve when the rotation speed is relatively low, and by a dump valve when the input shaft and output shaft are fully connected and in a high speed range,
The operating pressure of this friction plate pressurizing fluid can be easily and reliably adjusted over the entire rotation range, and in particular, when the output shaft is rotating at low speed, appropriate transmission torque and buffering effects can be achieved when the output shaft is fully engaged and at high speeds. The purpose is to obtain the same thing.

An embodiment of the present invention will be described based on FIGS. 4 to 7.

Note that the parts common to those in FIG.

In the centrifugal speed control drive mechanism 10, a dump valve 23 is provided at a symmetrical position on the large diameter portion 4a with respect to the centrifugal speed control valve 11.

This dump valve 23 has the large diameter portion 4. An easily replaceable valve body 24 is integrally attached to the outer peripheral surface of the valve body 24, and a governor weight 25 that can move forward and backward in the radial direction is fitted in a fluid-tight manner inside this valve body 24.
A friction plate suppressing fluid passage 28 for pushing the suppressing ring 8 formed through the throttle resistor 22 is opened on the inner end side of the governor weight 25, and operating pressure in the direction of external force is applied to the inner end surface of the governor weight 25. A coil spring 26 of an appropriate spring constant that is fitted into the inside of the valve body 24 and biases the governor weight 25 inward is attached to the outer end of the weight 25, and a coil spring 26 is attached to the base of the side wall of the valve body 24. A port 27 is provided in the port 27, which is opened and closed by the governor weight 25 to throttle and adjust the outflow resistance of the friction plate suppressing fluid.As shown in FIG. and at the point of complete coupling, the supply pressure P8
centrifugal speed control valve 11 when lower than and not overloaded.
When the operating pressure Pa given by starts increasing to the supply pressure P8 due to overload, the governor weight 25 controls the throttle of the port 27 to increase the pressure Pa slightly higher than the pressure Pa.
The coil spring 26 has an energizing pressure Pω' corresponding to the centrifugal force of the governor weight 25 acting radially outward on the governor weight 25 and an operating pressure Pa acting radially inward so as to be suppressed at energizing pressure Pk
The weight of the governor weight 25 and the spring constant of the coil spring 26 are set so as to satisfy the condition of equilibrium with Pk=Pa'''10Pω'.

Coil spring 2 so as to apply an appropriate pressure Pa″
In order to change the spring constant of 6, the coil spring 26 is designed to be easily replaceable.

Since the coil spring 26 has a biasing pressure Pk that is slightly larger than the sum of the biasing pressure Pω' due to the centrifugal force acting on the governor weight 25 and the operating pressure Pa in the high-speed range, in the high-speed range Normally, the port 27 remains closed, but when an overload is applied in a high-speed range, the operating pressure Pa of the friction plate suppression fluid increases due to the action of the centrifugal speed control valve 11, and the operating pressure Pa increases to
When ``/'' is reached, the port 27 is opened and the operating pressure is maintained at this pa''/, and the friction plate 6.7 slides to provide a damping effect.

As shown in FIG. 4, when the clutch is engaged, the operating pressure pae''/ controlled by the dump valve 23 is changed to the operating pressure Pae''/ controlled by the centrifugal speed control valve 11 when the clutch is engaged.
When adjusted to about 1.5 times e, the transmitted torque for the operating pressure Pae'' when the clutch is engaged becomes Te'', which is 1.5 times the steady torque T given by the operating pressure Pae of the centrifugal speed control valve 11. This is about 5 times, which is much lower than 3 to 4 times the control pressure Pc'' mentioned above, and provides a buffering effect against overload when the clutch is engaged.

Further, the operating pressure changes as pa''/ as the rotational speed decreases due to the dump valve 23, and finally matches the supply pressure P8.

By maintaining the pressure Pa″′ slightly higher than the pressure P3, the change in the transmitted torque at this time is almost constant T″
', which shows a value lower than the transmitted torque T'' when there is no dump valve.

In this way, there is a similar buffering effect even in the high speed range.

As described above, the dump valve 23 causes the pressure Pa''/ to increase from pae''/=1.5 pae at the complete coupling point as the rotational speed of the output shaft decreases, and finally the supply pressure Ps
matches.

As shown in FIG. 7, the governor weight 25 operates at the position indicated by the solid line at the connection point, and operates according to the biasing pressure Pke of the coil spring 26 and the biasing pressure Pωe' due to the centrifugal force of the governor weight 25. The port 27 is throttled so that the pressure is balanced, and the operating pressure is adjusted to Pae'''.

That is, Pke=Pae'''+Pωe'. Next, when the rotational speed of the output shaft decreases, the biasing pressure Pω' due to the centrifugal force of the governor weight 25 decreases, so the governor weight 25 Force P
k, it moves in the direction of the position shown by the dashed line in FIG. 7, that is, so as to narrow the port 27.

As a result, the working pressure Pa″′ is expressed by the equilibrium relational expression Pk=Pa
``''+Pω', but since Pω' has a larger decreasing rate than Pk, the operating pressure pa''/ continues to increase during the process, and finally, the energizing pressure Pω1' due to the centrifugal force of the governor weight 25 and the coil The biasing pressure Pkt of the spring 26 and the operating pressure are balanced to close the port 27, and the operating pressure at this time becomes equal to the supply pressure Ps.

That is, Pk,=Ps+P product 1'.

In the above explanation, it is assumed that Pωe' and Pω,' and Pke and Pkl are given, that is, the weight of the governor weight 25 and the spring constant of the coil spring 26 are known, but in reality, the governor weight 25 is Determine the weight of and calculate Pωe' and Pω1' from this,
Then, the formula Pke=1.5Pae+Pωe′ and Pk
The biasing pressure of the coil spring 26 is determined from t=P3+Pω1', and the spring constant is calculated from this.

Next, another embodiment of the present invention will be described based on FIGS. 8 and 9.

This combines the control pressure to the centrifugal speed control valve and the pressure supplied to the friction plate into one pressure fluid.The pressure of this pressure fluid corresponds to the control pressure, and is adjusted by the centrifugal speed control valve. The resulting pressure corresponds to the operating pressure.

The centrifugal speed control drive mechanism 103 in this embodiment has a centrifugal speed control valve 11a installed on the outer surface of the large-diameter portion 4a of the output shaft 4 so as to face the pressure fluid connection 29. The speed control valve 11a includes a governor weight 1 that can move forward and backward in the radial direction inside the valve body 12a.
3a in a fluid-tight manner, the passage 29 is communicated with the outer end of the governor weight 13a through the through hole 31 of the throttle resistor 30, and the governor weight 13a is connected to the inner end of the governor weight 133 with an external force. A coil spring 32 is attached to the side wall of the valve body 12a, and a coil spring 32 is attached to the side wall of the valve body 12a.
A port 15a1 that is opened and closed by the governor weight 13a to throttle and adjust the operating pressure Pa of the press ring 8, and a through hole 15b that conducts the operating pressure P3 to the inner end surface of the governor weight 13a are formed.

Here, the governor weight 13 supplied from the passage 29
Fluid pressure P acting on the outer end surface of a.

is balanced with the sum of the operating pressure Pa acting on the inner end surface of the governor weight 13a, the centrifugal force equivalent pressure Pω acting on the governor weight 13a during rotation, and the energizing pressure Pk of the coil spring 32, and the equation P.

=Pa+Pω+Pk holds true.

In addition, in the one provided with the centrifugal speed control drive mechanism 10a, the large diameter portion 4a is different from the centrifugal speed control valve 11a.
A dump valve 23a is also provided at a symmetrical position.

This dump valve 23a has an easily replaceable valve body 24a integrally mounted on the outer surface of the large-diameter portion 4a, and a governor weight 25a that can move forward and backward in the radial direction inside the valve body 24a in a liquid-tight manner. A friction plate suppressing fluid passage 28a for pushing the pressure ring 8 is opened on the inner end side of the governor weight 25a, and the governor weight 25a is fitted on the inner end side of the governor weight 25a in the direction of external force. Coil spring 3 with appropriate spring constant to energize
3 is attached, and the passage 29 for the pressure fluid is opened on the outer end side of the governor weight 253 so as to apply inward pressure to the outer end surface thereof, and the side wall of the valve body 24a is mounted by the governor weight 25a. A port 27a that is opened and closed to throttle and adjust the outflow resistance of the friction plate suppression fluid.
Establish and configure.

Note that the coil spring 33 is designed to be easily replaceable.

Here, the governor weight 25 is supplied from the passage 29.
The upper two fluid pressures P acting on the outer end surface of a.

are the operating pressure Pa''1 that acts on the inner end surface of the governor weight 25 when the dump valve 23a operates during overload, the centrifugal force equivalent pressure Pω' that acts on the governor weight 25a during rotation, and the bias of the coil spring 33. Equation P.

port 27 so that =Pa'+Pω'+Pk' holds true.
The weight of the governor weight 25a that narrows a and the spring constant of the coil spring 33 are determined.

If the operating pressure Pae''' when the clutch is fully engaged is set in advance so that the transmitted torque at that time is 1.5 times the steady transmitted torque T given by the centrifugal speed control valve, the output when the clutch is fully engaged is set in advance. Even if an excessive load torque is applied to the shaft 4, the governor weight 25a opens the port 27a as in the above embodiment, and the actual operating pressure of the friction plate suppressing fluid does not exceed the operating pressure Pa''/. Therefore, the transmitted torque is suppressed to T'', and load torque exceeding this can be buffered.

Applications of the present invention include a slipping clutch that uses a centrifugal speed control valve to control the speed of rolling mills, reciprocating pumps, blowers, etc. whose normal operation is under a constant torque load.

In either case, overloads are likely to occur due to foreign matter getting caught, and the centrifugal speed control valve cannot be expected to provide a buffering effect when the clutch is fully engaged and at high speeds. It can be prevented.

According to the present invention, in a variable speed device using a friction plate, the operating pressure P of the friction plate suppression fluid is adjusted by the centrifugal speed control valve, which is separate from the centrifugal speed control valve.
Since we also use a dump valve that can be adjusted to maintain an extremely high operating pressure P'' and suppress a sudden increase in operating pressure, the operating pressure will be adjusted by the centrifugal speed control valve due to overload. It is possible to prevent the risk of the transmitted torque increasing from T to T'' due to the increase in supply pressure Ps, and the operating pressure of the friction plate suppression fluid controlled by the centrifugal speed control valve can be easily and reliably maintained over the entire rotation range. As with the case when the output shaft rotates at low speed, the dump valve can provide an appropriate transmission torque and buffering effect even when fully connected and at high speed.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an embodiment of a centrifugal speed control drive mechanism with an overload buffer function, Figs. 2 to 4 are graphs explaining its operation, and Fig. 5 is an overload buffer according to the present invention. FIG. 6 is a sectional view taken along the line A-A of the device, FIG. 7 is an enlarged sectional view of the main part thereof, and FIG. 8 is a sectional view showing another embodiment of the present invention. , FIG. 9 is an enlarged sectional view of the main part thereof. 2...Input shaft, 4...Output shaft, 6, 7...Friction plate, 10
, 10a... Centrifugal speed control drive mechanism, 11.11a...
- Centrifugal speed control valve, 23゜23a...tanf valve,
24, 24a... Valve body, 25, 25a... Governor weight, 26... Coil spring, 27, 27a...
...Port, 28.28a...Friction plate suppression fluid passage, 3
3...Coil spring.

Claims (1)

[Claims] 1. On the output shaft side of a variable speed device using a friction plate, by adjusting the control pressure, the operating pressure of the friction plate suppressing fluid is automatically adjusted, and the rotational speed of the output shaft is set to an arbitrary constant value. A friction plate is installed on the output shaft side of the centrifugal speed control valve so that the centrifugal speed control valve maintains the rotational speed of the output shaft constant due to overload. Adjusting the control pressure of the centrifugal speed control valve over the entire rotational speed range when operating to rapidly increase the operating pressure of the suppressing fluid to the supply pressure, when this operating pressure is lower than the supply pressure and when not overloaded. By the predetermined weight of a governor weight that slides radially within the valve body, the restriction of the port in the valve body that discharges the working fluid is maintained so as to maintain a working pressure slightly higher than the set working pressure. a biasing pressure corresponding to the generated radially outward centrifugal force, a biasing pressure in the radial direction by a coil spring with a predetermined spring constant attached to press the governor weight in the radial direction J, and the governor weight. 1. An overload shock absorber comprising a dump valve which is controlled to open and close in balance with a radial biasing pressure caused by a pressure fluid acting on a plane perpendicular to the direction of sliding force of the damper. 2. The dump valve has a governor weight that is liquid-tightly fitted inside the valve body and can move forward and backward in the radial direction, and a passage that conducts the working pressure of the friction plate suppression fluid is opened at the inner end of the governor weight. At the same time, the governor weight is energized inwardly, and a port is provided in the side wall of the valve body to throttle and adjust the outflow resistance of the friction plate suppressing fluid, which is opened and closed by the governor weight. The overload buffer device according to claim 1, wherein the overload buffer device is energized by a coil spring provided on the end side. 3. The dump valve has a governor weight that is liquid-tightly fitted inside the valve body and is movable in the radial direction, and a passage is opened at the inner end of the governor weight to conduct the working pressure of the friction plate suppression fluid. At the same time, the governor weight is energized inwardly, and a port is provided in the side wall of the valve body to throttle and adjust the outflow resistance of the friction plate suppressing fluid, which is opened and closed by the governor weight. 2. The overload buffer device according to claim 1, wherein the overload buffer device is energized by a pressure fluid conducted to the end side and a coil spring attached to the inner end side of the governor weight.