CA1120828A

CA1120828A - Control means for hydraulic clutches

Info

Publication number: CA1120828A
Application number: CA000304986A
Authority: CA
Inventors: Mitsuhiro Tani; Hideo Watanabe; Shinta Tanaka
Original assignee: Iseki Agricultural Machinery Mfg Co Ltd
Current assignee: Iseki Agricultural Machinery Mfg Co Ltd
Priority date: 1977-06-09
Filing date: 1978-06-08
Publication date: 1982-03-30
Also published as: FR2393979A1; DE2825261C2; GB1601256A; DE2825261A1

Abstract

ABSTRACT
There is provided a control means for hydraulic clutches, which comprises a change-over mechanism consisting of a control lever; a shift lever rotatably connected to the fulcrum of the control lever; and a toggle spring whereby the control lever and shift lever are connected to each other, which is moved to right and left with respect to the fulcrum of the control lever, and a change-over valve actuated by the shift lever of the change-over mechanism.

Description

The present invention relates to a control means for hydraulic clutches and, more particularly, to a control means for a change-over valve for hydraulic clutches through which a pressurized oil is supplied into a hydraulic clutch whereby a rot:ary driving force from the engine is connected to or dis-connected from a PT0 drive shaft of, for example, a tractor.
A conventional hydraulic clutch of this kind is gener-ally provided with a rotary spool type or slide spool type change-over valve to which a control handle is connected via a lever. The hydraulic clutch is let in and out while opening and closing an oil passage in the change-over valve by operating the control handle to rotate or slide the spool. When the control handle is slowly operated, the spool is rotated or slid slowly. In this case, the clutch is in a half-operated state for an unduly long time. This causes the lining of the clutch to be worn early or causes inconveniences due to the unnecessary heat generated. Especially, a clutch having a paper lining which has a low resistance to heat is easily damaged.
An object of the present invention is to eliminate the above-mentioned drawbacks encountered in the prior art control means for clutches.
Another object of the present invention is to provide a control means for hydraulic clutches which permits rotating or sliding the spool of the change-over valve at an optimum speed constantly irrespective of the operation speed of the control handle to shorten the time during which the clutch is in a half-operated state and prevent an early wear on the lining and generation of unnecessary heat.
To these ends, according to the invention, there is provided a control means for hydraulic clutches, which comprises a change-over mechanism consisting of a control lever, a shift ' li;~O828 lever rotatably connected to the fulcrum of the control lever, and a toggle spring whereby the control lever and shift lever are connected to each other, which is moved to right and left with respect to the fulcrum of the control lever, and a change-over valve actuated by the shift lever of the change-over mechanism.
The above and other objects as well as advantageous features of the invention will become clear from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.
Figure 1 is a side elevational view in cross section of a principal portion of a hydraulic clutch to which a control means according to the present invention is applied;
Figure 2 is a side elevational view of an embodiment of the present invention' Figure 3 is a front elevational view of the embodiment as shown in Figure 2, Figure 4 is a side elevational view of another embodi-ment of the present invention, and Figure 5 is a plan view of the embodiment as shown in Figure 4.
The construction of the present invention will be described in detail with reference to the accompanying drawings.
Referring to Figure l,,reference numeral 1 denotes a transmission case for a tractor, 2 a multiple disc clutch provided in the transmission case 1, 3 a rotary change-over valve provided on the outer surface of the transmission case 1, 4 a spool, and 5 a valve lever mounted on the spool 4. When the valve lever 5 is engaged with a stopper 6 or when the valve lever 5 is moved to a position as shown in a solid line in Figure 1, where the 11i~0828 clutch is let in, a pressurized oil introduced into the change-over valve 3 through a pipe 7 flows through an oil passage 8 to forwardly move a piston 10 fitted in a clutch cylinder 9, so that the rotary driving force of a clutch shaft 11 is transmitted from the clutch cylinder 9 to a PTO drive shaft 12. When the valve lever 5 is engaged with a stopper 13 or when the valve lever is moved to a position as shown in a chain line in Figure 1, where the clutch is let out, the change-over valve 3 is so operated as to stop the flow of the pressurized oil into the passage 8 so that the rotary drive force of the hydraulic clutch

2 is stopped due to the resilient force of a spring 14.
The control means according to the present invention for such a hydraulic clutch 2 is constructed as shown in Figures 2 and 3.
Referring to Figures 2 and 3, a valve lever 5 and a shift lever 15 are rotatably mounted on a spool 4 of a change-over valve 3. The shift lever 15 is connected to a control handle 17 via a link mechanism 16. The valve lever 5 and shift lever 15 mounted on the spool 4 are provided with support pins 18, 19, respectively, to which both ends of a toggle 'spring 20 are fastened to there~y connect these levers 5, 15 to each other.
Outside the outer end portions of the levers 5, 15, stoppers 6, 13, 21, 22 are provided. The effective length /1 of the shift lever 15 is longer than that R2 of the valve lever 5.
When the valve lever 5 is moved to a position as shown in a chain line in Figure 2 where the valve lever 5 is out of operation, the shift lever 15 and valve lever 5 are supported by the right-hand stoppers 13, 22, respectively, with the support pins 19, 18 positioned on the right of the spool 4. At this time, the levers 15, 5 are in the shape of a dogleg. When the control handle 17 is then rotated counter-clockwise, the shift lever 15 is rotated in the same direction via the link mechanism 16.

11'~08Z8 When an imaginary straight line passing the axes of the support pins 18, 19 is on the right of the center of the spool 4 during the rotation of the shift lever 15, the valve lever 5 is urged in the counter-clockwise direction by the toggle spring 20 to prevent the valve lever 5 from being moved. However, when the above-mentioned imaginary line, i.e. the axis line of the toggle spring 20 has passed to any extent the center of the spool 4 the valve lever 5 is urged in the clockwise direction by the toggle spring 20. As a result, the lever 5 is rotated clockwise so as to be engaged with the lefthand stopper 6, , while the shift lever 15 reaches the end of its stroke or is engaged with the stopper 21. Namely, the levers 5, 15 are at this time in positions as shown in solid lines in Figure 2.
In short, the change-over valve 3 is opened and closed while the spool 4 is rotated in accordance with the rotary movement of the valve lever 5. During the operation of the change-over valve 3, a back pressure of the pressurized oil is exerted on the piston 10 of the hydraulic clutch 2 as shown in Figure l so as to let in the same.
When the control handle 17 is rotated clockwise with the hydraulic clutch 2 let in, the letting-out operation therefor is carried out in substantially the same manner as in the above case ex~ept that the shift lever 15 and valve lever 5 are rotated in the direction opposite to that in which they are rotated in the above case. The operation for letting out the hydraulic clutch 2 is carried out by the action of the change-over valve 3 in accordance with the rotation of the spool 4 to release the piston 10 of the clutch 2 from the back pressure of the pressurized oil.
In the control means for hydraulic clutches according to the present invention, which is constructed as mentioned above, the valve lever 5 is never rotated while the toggle spring 20 0~32B

does not reach the center of the spool 4 after the shift lever 15 has begun to be rotated by operating the control handle 17, it is rotated by the resilient force of the toggle spring 20 when the spring has exceeded the center of the spool 4 to any extent. The change over valve 3 is opened and closed via the spool 4 by the rotation of the valve lever 5. Namely, the change-over valve 3 can be opened and closed at a predetermined high speed at any time irrespective of the operation speed of the control handle 17.
Therefore, the control means according to the present invention permits preventing the hydraulic clutch from being slipped to be put into a half-operated state. It also permits preventing an early wear on the lining and generation of unnece$sary heat.
When the effective length ~1 of the shift lever 15 is greater than that ~2 of the valve lever 5 as shown in Figure 2 so as to render the angle of rotation ~ of the shift lever 15 greater than that ~ of the valve lever 5, the time of operation of the valve lever 5 may be shortened.
The control means for hydraulic clutches according to - the present invention may also be constructed as shown in Figures 4 and 5.
Referring to Figures 4 and 5, a shaft 25 of a control handle 32 is rotatably fixed at its base end portion to a bearing plate 24 which is disposed below a meter panel 23 of a tractor.
A control lever 27 provided vertically with a support pin 26 is secured at its base portion to the shaft 25, and a shift lever 29 provided vertically with a support pin 28 is rotatably fitted at its base portion in the shaft 25. Between the support pins 26, 28, a toggle spring 30 is so provided that it is out of the axis of the shaft 25. A valve lever 5 and the shift lever 29 are pivotally connected to each other with a connecting rod 31.
The upper portion of the shaft 25 is passed through the meter panel 23, and the control handle 32 is secured to the upper end of the shaft 25.

)8Z8 When the control handle 32 is moved to a position as shown in chain line in Figure 5, where the clutch is let in, the support pins 26, 28 are engaged with stoppers 33, 34, respectively, which are provided in recesses in the bearing plate 24, and the control lever 27 works to retain by the toggle spring 30 the shift lever 29 in a position as shown in solid line in Figure 5.
When the control handle 32 is rotated to a position as shown in solid line in Figure 5, the support pin 26 is engaged with a stopper 35, and the control lever 27 reaches a position as shown in chain line to rotate the toggle spring 30 beyond the center of the shaft 25. At this time, the toggle spring 30 causes the shift lever 29 to be rotated until the support pin 28 has been engaged with a stopper 36 or to a posi-tion as shown in chain line in Figure 5, where the clutch is let out, while the connecting rod 31 is rearwardly rotated until the valve lever 5 has been engaged with a stopper 13.
When the control handle 32 as shown in Figures 4 and 5 is then rotated, the control lever 27 is actuated to rotate the shift lever 29 via the toggle spring 30 so that the shift lever 29 is retained by the toggle spring 30 in a position where the clutch is let in or in a position where the clutch is let out.
Thus, the clutch can be prevented from being unnecessarily moved.
Therefore, when the control lever 27 is rotated to allow the toggle spring 30 to be moved beyond the center of the shaft 25, the shift lever 29 is forcibly and accurately rotated in a desired direction.
Thus, the present invention provides a control means of a very simple construction for hydraulic clutches, which per-mits letting in and out a hydraulic clutch at a predeterminedhigh speed at any time irrespective of the operation speed of the . - 6 -)8Z8 control handle 32 so that the hydraulic clutch is never put into a half-operated state, and which permits preventing an early wear on the lining and generation of unnecessary heat.
Incidentally, when a slide spool type change-over valve, in which a spool inserted in a sleeve is axially slidingly moved to open and close the oil passage, is used in the present invention, a push arm which can be rotated as it is always in contact with the tip of the spool may be provided, which arm has, for example, a link mechanism as shown in Figure 2 or a connecting rod 31 as shown in Figure 4 pivotally connected to the tip thereof, to obtain the same effect.
The present invention is not, of course, limited to the above-described embodiments; it may be modified in various ways within the scope of the appended claims.

Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. For use with a hydraulic clutch, and a valve means operatively connected to said hydraulic clutch for control-ling the flow of fluid pressure to said clutch for effecting the operation of said clutch between an operative engaged position and an inoperative disengaged position wherein said valve means is remotely disposed from said clutch, the improve-ment of control means for uniformly activating said clutch in a positive manner so as to prohibit any delay in the transi-tion interval of shifting said clutch between an operative and inoperative position comprising a shift lever and a control lever, pivot means for pivotally mounting said shift lever relative to said control lever, whereby said pivot means defines a fulcrum about which said levers are relatively pivoted; an actuating means connected to one of said levers to pivot therewith about said pivot means, and a spring means interconnected between said levers whereby said spring is disposed to one side of said pivot means in the engaged posi-tion of said clutch and to the other side of said pivot means in the disengaged position of said clutch and means inter-connecting said valve means to said shift lever whereby the actuation of said valve means is rendered immediately responsive.

2. The invention as defined in claim 1, and including a valve lever connected to said valve means for actuating said valve means; and means interconnecting said valve lever with said shift lever whereby said valve lever and connected valve means is rendered responsive to the displacement of said shift lever.

3. The invention as defined in claim 1, wherein said actuating means is connected to said control lever and pivoted about said pivot means.

4. The invention as defined in claim 3, wherein said means interconnecting said shift lever to said valve lever comprises a connecting rod whereby the actuation of said valve lever is directly responsive to the movement of said shift lever.

5. The invention as defined in claim 1, wherein said actuating means comprises a control handle, said control handle being connected to said control lever whereby said control lever is rendered responsive to the displacement of said control handle.

6. A hydraulic clutch, a valve means connected to said clutch for controlling the flow of fluid pressure to said clutch for effecting the operation of said clutch between an operative engaged position and an inoperative disengaged position wherein said valve means is remotely dis-posed from said clutch and a control means for uniformly activating said clutch in a positive responsive manner so as to prohibit any delay in the transition interval of shifting said clutch between an operative and inoperative position to minimize wear, said control means comprising a shift lever and a control lever, pivot means pivotally connecting said levers whereby said shift lever can pivot relative to said control lever, a control handle connected to said control lever for effecting the displacement of said control lever between a first and second position, a spring drive inter-connected between said shift lever and control lever whereby said spring drive effects the positive drive of said shift lever in response to said control lever whereby said spring means is disposed to one side of said pivot means in the first position of said control lever and to the other side of said pivot means in the second position of said control lever, said valve means including a valve stem, a valve lever connected to said valve stem, and a means interconnecting said shift lever to said valve lever whereby said valve means is rendered directly responsive to the displacement of said shift lever respective of the operational speed at which the control handle is actuated.