Claims:WE CLAIM:
1. A control valve assembly (100) for controlling a two-speed power shift transmission for providing intermediate Hi-Low speeds for a selected gear of a work vehicle, said control valve assembly (100) comprising:
• a housing (101) with an inlet (102) defined thereon;
• a priority valve (105) configured downstream of said inlet (102), said priority valve (105) configured for allowing a steady flow of oil through said control valve assembly (100);
• an adjustable relief valve (110) positioned downstream of said priority valve (105), said adjustable relief valve (110) configured for limiting the pressure in said control valve assembly (100);
• a solenoid operated four-way two-position (4/2) directional control valve (115), said directional control valve (115) operable by an activation means (116), said directional control valve (115) in an non-actuated state being configured to permit flow of oil to a first clutch (120a), while in an actuated state said directional control valve (115) directs the flow of oil to a second clutch (120b);
• two pairs of filling and dumping valves (130) configured to provide modulation of hydraulic pressure, wherein a first pair of filling and dumping valves (130a) is configured to control the raising and lowering of hydraulic pressure for facilitating smooth engagement and disengagement of said first clutch (120a), while a second pair of filling and dumping valves (130b) is configured to control the raising and lowering of hydraulic pressure for facilitating smooth engagement and disengagement of said second clutch (120b);
• a first accumulator (150a) provided downstream of said first pair of filling and dumping valves (130a), said first accumulator (150a) being configured for controlling high speed modulation time; and
• a second accumulator (150b) provided downstream of said second pair of filling and dumping valves (130b), said second accumulator (150b) being configured for controlling low speed modulation time.
2. The control valve assembly (100) as claimed in claim 1, wherein said control valve assembly (100) is configured for changing the direction of flow of fluid from said first clutch (120a) to said second clutch (120b), and vice versa, thereby facilitating shifting of gears without the need of de-clutching by engaging said first clutch (120a) while simultaneously disengaging said second clutch (120b) within a predetermined period of time.
3. The control valve assembly (100) as claimed in claim 1, wherein said control valve assembly (100) includes a disengagement valve (160) fluidly connected between a main pressure line and a reservoir tank line, said disengagement valve (160) configured to keep said control valve assembly (100) in an idle condition by bypassing the oil to a reservoir tank by energizing the solenoid of said disengagement valve (160) when there is no requirement of the two intermediate speeds.
4. The control valve assembly (100) as claimed in claim 3, wherein said disengagement valve (160) is connected parallel to said adjustable relief valve (110).
5. The control valve assembly (100) as claimed in claim 3, wherein a disengagement valve manifold is defined in said housing (101) for housing said disengagement valve (160).
6. The control valve assembly (100) as claimed in claim 1, wherein said first clutch (120a) is connected to an intermediate high speed drive arrangement, while said second clutch (120b) is connected to an intermediate low speed drive arrangement.
7. The control valve assembly (100) as claimed in claim 1, wherein said first accumulator (150a) and said second accumulator (150b) are integrated with said housing (101).
8. The control valve assembly (100) as claimed in claim 1, wherein said activation means (116) includes a button or a lever (not shown in figures) capable of being operated by a finger, said activation means (116) being provided near a main gear shifting lever of a tractor.
9. The control valve assembly (100) as claimed in claim 1, wherein a plate (124) with an orifice (125) defined therein is provided between said directional control valve (115) and each of said accumulators (150a and 150b) to provide a restricted passage to the flow of oil therebetween.
10. The control valve assembly (100) as claimed in claim 1, wherein each of said accumulators (150a and 150b) includes a piston (151), a spring (152), and an end-stop (153) assembled therein.
, Description:FIELD
The present disclosure relates to the field of control valves for controlling power shift transmissions.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicate otherwise.
Priority valve: - The term “priority valve” hereinafter refers to a valve whose function is to allow hydraulic fluid flow to certain functions within a hydraulic system when the pressure is greater than or equal to a specified level
Four ways two position directional control valve (4/2 valve): - The term “Four way two position directional control valve” hereinafter refers to a valve having four ports and two spool positions.
Adjustable relief valve: - The term “adjustable relief valve” hereinafter refers to a type of safety valve used to control or limit the pressure in a system, wherein the limiting pressure can be adjusted.
Filling and dumping valve: - The term “filling and dumping valve” hereinafter refers to a valve that is used to get proper modulation of pressure during engagement and disengagement of clutches.
Accumulator: - The term “filling and dumping valve” hereinafter refers to a pressure storage reservoir in which a non-compressible hydraulic fluid is held under pressure that is applied by an external source of mechanical energy. The external source can be an engine, a spring, a raised weight, or a compressed gas
Disengagement valve: - The term “disengagement valve” hereinafter refers to a valve that is used to bypass the control valve assembly by directing the entire flow of oil to an oil reservoir tank.
Modulation time: - The term “modulation time” hereinafter refers to a time required for the achieving a predetermined hydraulic pressure for carrying out any further action.
High speed modulation time: - The term “high speed modulation time” hereinafter refers to a time required for the achieving a predetermined hydraulic pressure required for engaging a clutch corresponding to a high speed drive.
Low speed modulation time: - The term “low speed modulation time” hereinafter refers to a time required for the achieving a predetermined hydraulic pressure required for engaging a clutch corresponding to a low speed drive.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Typically, tractor transmission is required to get the desired torque on wheels depending upon various applications. In a conventional mechanical transmission clutch multiple pairs of gears are used to achieve a fixed speed and a fixed torque. However, these fixed speeds become a problem when there is a need of providing in-between speeds for a selected gear. This results in less productivity as the driver gets less time to handle any difficult situation, such as a sudden torque requirement when it is needed to overcome slope or mud.
The problem is conventionally solved by adding intermediate hi-low speeds for each gear. The best provision to operate the hi-low speed is to use separate wet clutches dedicated to high and low speed gears in the transmission system. This system shifts gears by engaging one clutch while simultaneously disengaging another clutch within a certain period of time. This calls for a need of a control valve to operate these wet clutches. The existing solutions available in the market use two different control valves for high and low speed. However, these control valves include external accumulator as a pressure modulation device, which consumes more space and provides less control over the modulation time. Presently, there is no provision to disengage the hi-low valve when there is no need thereof.
There is, therefore, felt a need of a control valve assembly for controlling a two-speed power shift transmission that alleviates the above mentioned drawbacks.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a control valve assembly for controlling a two-speed power shift transmission.
Another object of the present disclosure is to provide a control valve assembly for controlling a two-speed power shift transmission that is small in size.
Another object of the present disclosure is to provide a control valve assembly for controlling a two-speed power shift transmission that is quick in operation.
Yet another object of the present disclosure is to provide a control valve assembly for controlling a two-speed power shift transmission that includes internal accumulators.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure is about a control valve assembly that is used for controlling a two-speed power shift transmission for providing intermediate Hi-Low speeds for a selected gear of a work vehicle such as tractor. The control valve assembly comprises a housing with an inlet defined thereon, a priority valve configured downstream of the inlet for allowing a steady flow of oil through the valve assembly, an adjustable relief valve positioned downstream of the priority valve, the adjustable relief valve configured for limiting the pressure in the valve assembly, a solenoid operated four-way two-position (4/2) directional control valve operable by an activation means, a first pair of filling and dumping valves configured for controlling the raising and lowering of hydraulic pressure such as to facilitate smooth engagement and disengagement of a first clutch, a second pair of filling and dumping valves configured for controlling the raising and lowering of hydraulic pressure such as to facilitating smooth engagement and disengagement of a second clutch, a first accumulator provided downstream of the first pair of filling and dumping valves for controlling high speed modulation time, a second accumulator provided downstream of the second pair of filling and dumping valves for controlling low speed modulation time.
In an embodiment, the directional control valve in an non-actuated state is configured to permit flow of oil to a first clutch, while in an actuated state the directional control valve directs the flow of oil to a second clutch.
In an embodiment, the control valve is configured for changing the direction of flow of fluid from the first clutch to the second clutch, and vice versa. This helps in facilitating shifting of gears without the need of de-clutching by engaging the first clutch while simultaneously disengaging the second clutch within a predetermined period of time.
In an embodiment, the control valve assembly includes a disengagement valve that is fluidly connected between a main pressure line and a reservoir tank line. The disengagement valve is configured to keep the control valve assembly in an idle condition by bypassing the oil to a reservoir tank by energizing the solenoid of the disengagement valve when there is no requirement of the two intermediate speeds.
In an embodiment, the first clutch is connected to an intermediate high speed drive arrangement, while the second clutch is connected to an intermediate low speed drive arrangement.
In an embodiment, the first accumulator and the second accumulator are integrated with the housing of the valve assembly .
In an embodiment, the disengagement valve is connected parallel to the relief valve.
In an embodiment, the activation means includes a button or a lever capable of being operated by a finger. The activation means is provided near a main gear shifting lever of the tractor.
In an embodiment, a disengagement valve manifold is defined in the housing for housing the disengagement valve.
In an embodiment, a plate an orifice defined therein is provided between the directional control valve and each of the accumulators, to provide a restricted passage to the flow of oil therebetween.
In an embodiment, each of the accumulators includes a piston, a spring, and an end-stop assembled therein.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWING
The control valve for controlling a two-speed power shift transmission of the present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 shows a front view of the control valve assembly, in accordance with an embodiment of the present disclosure;
Figure 2 shows a side view of the control valve assembly of the Figure 1;
Figure 3 shows a top view of the control valve assembly of the Figure 1;
Figure 4 shows a cross-sectional view of the control valve assembly of the Figure 1;
Figure 5 shows a cross-sectional view of an accumulator of the control valve assembly; and
Figure 6 shows the flow of oil through the control valve assembly.
LIST OF REFERENCE NUMERALS USED IN DETAILED DESCRIPTION AND DRAWING
100 – Control valve assembly
101 – Housing
102 – Inlet
105 – Priority valve
110 – Adjustable relief valve
115 – Directional control valve
116 – Actuation means
120a – First clutch
120b – Second clutch
124 – Plate
125 – Orifice
130 – Filling and dumping valves
130a – First pair of filling and dumping valves
130b – Second pair of filling and dumping valves
150a – First accumulator
150b – Second accumulator
151 – Piston
152 – Spring
153 – End-stop
160 – Disengagement valve
161 – Disengagement valve manifold

DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a”, “an”, and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises”, “comprising”, “including”, and “having”, are open ended transitional phrases and therefore specify the presence of stated features, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, elements, components, and/or groups thereof.
When an element is referred to as being “mounted on”, “engaged to”, “connected to”, or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Terms such as “inner”, “outer”, “beneath”, “below”, “lower”, “above”, “upper”, and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
A control valve assembly 100 for controlling a two-speed power shift transmission is disclosed in the present application. The control valve assembly 100 controls the intermediate Hi-Low speeds for a selected gear of a tractor. The intermediate Hi-Low speed is achieved by the selective engagement and disengagement of a first clutch 120a and a second clutch 120b. The housing of the control valve assembly 100 comprises a plurality of ports, a plurality of galleries, and is further configured to accommodate a plurality of valves.
In an embodiment, the first clutch 120a is connected to an intermediate high speed drive while the second clutch 120b is connected to an intermediate low speed drive.
The control valve assembly 100 in accordance with an embodiment of the present disclosure is described with the help of Figures 1-6.
Figure 1 shows a front view of the control valve assembly 100, while the Figure 2 and Figure 3 show a side view and a top view of the valve assembly of Figure 1.
The control valve assembly 100 comprises a housing 101 with an inlet 102 defined thereon, a priority valve 105, an adjustable relief valve 110, a directional control valve 115, an actuation means 116, a first pair of filling and dumping valves 130a, a second pair of filling and dumping valves 130b, a first accumulator 150a, a second accumulator 150b, and a disengagement valve 160. All these components of the control valve assembly 100 are fluidly connected to each other via internally defined ports and passages.
The flow of pressurized oil gets divided into two streams in the inlet 102. One stream of oil enters the control valve assembly through the priority valve 105 while any excess oil flows to the clutches for lubrication. The oil stream from the priority valve 105 reaches the adjustable relief valve 110 first. The directional control valve 115 is connected in parallel to the adjustable relief valve 110. Downstream of the directional control valve 115 the entire valve assembly is divided into two identical sections. One of the sections corresponds to the intermediate high speed while another section corresponds to the intermediate low speed. These two sections generates optimum pressure modulation curves during engagement and disengagement of the clutches.
After passing through the directional control valve 115 the oil stream passes through an orifice 125 defined in a plate 124 and then pilot operated pressure modulation valve and then to the accumulator (150a or 150b).
Downstream of the first or second accumulator (150a or 150b), the flow stream is connected to the first or second clutch (120a or 120b). The disengagement valve 160 is also fluidly connected in parallel to the adjustable relief valve 110. In an actuated position the adjustable relief valve 110 directs the entire flow of oil to a reservoir tank.
The priority valve 105 is configured downstream of the inlet 102. The priority valve 105 is configured for allowing a steady flow of oil through the control valve assembly 100. The adjustable relief valve 110 is positioned downstream of the priority valve 105 and is configured to limit the maximum pressure in the control valve assembly 100. The solenoid operated four-way two-position (4/2) directional control valve 115 is provided between the priority valve 105 and the adjustable relief valve 110. The directional control valve 115 is operated by the activation means 116. In a non-actuated state the directional control valve 115 permits flow of oil to the first clutch 120a, while in an actuated state the directional control valve 115 directs the flow of oil to the second clutch 120b. Two pairs of filling and dumping valves 130 are provide modulation of hydraulic pressure, wherein the first pair of filling and dumping valves 130a is configured to control the raising and lowering of hydraulic pressure for facilitating smooth engagement and disengagement of the first clutch 120a, while the second pair of filling and dumping valves 130b is configured to control the raising and lowering of hydraulic pressure for facilitating smooth engagement and disengagement of the second clutch 120b. The first accumulator 150a is provided between the first pair of filling and dumping valves 130a and the first clutch 120a. The first accumulator 150a controls high speed modulation time. The second accumulator 150b is provided downstream of the second pair of filling and dumping valves 130b and before the second clutch 120b. The second accumulator 150b control low speed modulation time.
Figure 4 shows a cross-sectional view of the control valve assembly 100, while Figure 5 illustrates a cross-sectional view of an accumulator (150a or 150b) used in the control valve assembly 100.
The flow of oil through the control valve assembly 100 is depicted in Figure 6.
The control valve assembly 100 is configured for changing the direction of flow of fluid from the first clutch 120a to the second clutch 120b, and vice versa. This facilitates shifting between the intermediate Hi-Low speeds without the need of de-clutching by engaging the first clutch 120a while simultaneously disengaging the second clutch 120b within a predetermined period of time.
In an embodiment, the control valve assembly 100 includes the disengagement valve 160 that is fluidly connected between a main pressure line and the reservoir tank line, the disengagement valve 160 is configured to keep the control valve assembly 100 in an idle condition by bypassing the oil to a reservoir tank by energizing the solenoid of the disengagement valve 160 when there is no requirement of the two intermediate speeds. The disengagement valve 160 is connected parallel to the adjustable relief valve 110. The disengagement valve 160 acts as a safety feature to drain the oil so as to control the pressure. This improves the safety rating of the tractor and associated machinery.
The first clutch 120a is connected to an intermediate high speed drive arrangement, while the second clutch 120b is connected to an intermediate low speed drive arrangement.
In another embodiment of the present disclosure, the first accumulator 150a and the second accumulator 150b are integrated with the housing 101.
In an embodiment, the activation means 116 includes a button or a lever that can be operated by a finger. The activation means 116 is provided near a main gear shifting lever of the tractor.
A disengagement valve manifold 161 is defined in the housing 101 for housing the disengagement valve 160.
The functions of the control valve assembly 100 are as follows:
i) Changing the direction of flow, from one clutch to another;
ii) Setting the hydraulic pressure require to engage each of the clutches;
iii) Modulation of hydraulic pressure at the time of engagement and disengagement of the clutches;
iv) Providing lubrication for clutches; and
v) Disengaging both the clutches when there is no intermediate speed (two speed) requirement.
The function and details of various components of the control valve assembly 100 are the followings-
i) Priority valve: The priority valve maintains a steady flow irrespective of pump speed. The priority valve is designed and tuned to the requirement of the control valve assembly 100.
ii) Adjustable relief valve: The function of the relief valve is to limit max pressure. This is a kind of adjustable relief valve, it can be used for different pressure setting depends on clutch requirement.
iii) Solenoid operated directional control valve: A four way two position solenoid operated directional control valve is energized by an actuation means provided on main gear shifting lever of the tractor. It normally allows oil flow to the first clutch, which is connected on a high speed gear arrangement. When an actuation signal is received, the solenoid valve allows the flow of oil to the second clutch, which is connected on a low speed gear arrangement.
iv) Filling and dumping valve: Filling and dumping valves are used to get the required modulation of hydraulic pressure during engagement and disengagement of clutches. There are four identical filling and dumping valves are used, two valves are used to control the raise and lower pressure of high speed clutch engagement and remaining two controls the same for low speed clutch engagement. These filling and dumping valves are internally connected with accumulator. These valves are mainly contributing to decide the ramp up and ramp down modulation time.
v) Accumulator: There are two accumulator used in the control valve assembly 100, one for controlling high speed modulation time and the another is for controlling low speed modulation time. Both accumulators are identical in design. The accumulator is designed in such a way that, they start working at the end of the stroke of the respective pairs of filling and dumping valves. This creates the next step of the pressure modulation curve. The accumulators are integrated with the housing of the valve assembly.
vi) Disengagement valve: When there is no requirement of two speed, to keep the control valve in idle by bypassing the entire oil to tank by energizing this solenoid operated valve. The valve is placed between the main pressure line and tank line. It is placed outside of the control valve manifold, with the help of a separate manifold with the required cavity. The same valve can be used for tow start of the tractor, when the hydraulic system fails.
The plate 124 with the orifice 125 defined therein is provided between the directional control valve 115 and each of the accumulators (150a and 150b). The orifice 125 provides a restricted passage to the flow of oil.
In an embodiment, each of the accumulators (150a and 150b) includes a piston 151, a spring 152, and an end-stop 153 assembled therein.
The control valve manifold design is easily manufactures by a 3D printing process to avoid excess weight and to avoid unwanted machining. This simplifies the manufacturing process thereof.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a control valve for controlling a two-speed power shift transmission that:
• provides a jerk free on the go shifting of speed ratios without the need of de-clutching;
• improves productivity of the driver;
• incorporates inbuilt accumulators and reduces the number of parts/components;
• is simple in construction; and
• provides a disengagement valve which acts as a safety feature to drain the oil, thus improving the safety rating of the machine.
The foregoing description of the specific embodiments so fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, or group of elements, but not the exclusion of any other element, or group of elements.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.