Speed-changing valve group and engineering machinery

Abstract

The present invention relates to the technical field of engineering machinery, and specifically discloses a speed change valve group and engineering machinery. The speed change valve group includes a first control valve, the first control valve includes a first valve body and a first valve core, the first valve body is provided with an input oil port and an output oil port, and the first valve body is also provided with a first throttle oil channel and a second throttle oil channel, the input oil port is used to connect an oil pump, and the output oil port is used to connect a clutch; the first valve core can slide relative to the first valve body and has a left position and a right position, when the first valve core is in the left position and the right position, the first throttle oil channel is connected to the input oil port and the output oil port. At this time, the clutch is filled with oil through the first throttle oil channel and the second throttle oil channel at the same time, which can effectively improve instantaneous pressure shock and avoid sudden pressure change; when the first valve core is in the right position, the second throttle oil channel has a maximum opening and is connected to the input oil port and the output oil port, and when the first valve core moves from the right position to the left position, the opening of the second throttle oil channel gradually decreases to zero.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a speed change valve group and engineering machinery. Background Art

[0002] In the field of engineering machinery, speed changes other than continuously variable transmission mostly rely on gears in different speed ranges to achieve vehicle speed increases or decreases. Since the transmission mechanisms corresponding to different gears are different, the torque impact generated by the transmission device when switching gears varies in size, thus affecting the stability of the entire machine during movement.

[0003] The smoothness of the shifting process is a key indicator of the stability of the entire machine's operation and a crucial step in verifying the rationality of the overall matching design. Improper flow matching and the oil filling interval caused by pressure differentials can easily cause hydraulic shock at the critical filling and pressure buildup points, significantly affecting the characteristics of the clutch clamping mechanism, leading to gear engagement fluctuations and affecting the smoothness of the shifting process. Hydraulic shock refers to the phenomenon of a sudden valve closure or abrupt cessation of movement during sudden startup, shutdown, speed change, or direction reversal in the hydraulic system, resulting in the instantaneous formation of very high peak pressures in the system due to the effects of fluid pressure and the inertia of moving components.

[0004] Existing speed-shifting valve assemblies, such as those disclosed in the earlier patent application CN202010338623.5, utilize a valve core assembly that simultaneously connects the pilot oil inlet with the first oil chamber and the main oil inlet with the second oil chamber as the valve core assembly slides within the valve chamber. This allows the pilot oil provided by the pilot oil inlet and the working oil provided by the main oil inlet to simultaneously supply oil to the oil outlet, thereby rapidly filling the clutch main oil circuit. However, this speed-shifting valve assembly is prone to hydraulic shock at the moment of filling, resulting in sudden pressure changes. Summary of the Invention

[0005] The object of the present invention is to provide a speed change valve group and an engineering machine to solve the problem that the existing speed change valve group is prone to generate pressure shock during gear shifting.

[0006] In one aspect, the present invention provides a speed-changing valve group, the speed-changing valve group including a first control valve, the first control valve including:

[0007] a first valve body, the first valve body being provided with an oil input port and an oil output port, the first valve body being further provided with a first throttle oil passage and a second throttle oil passage, the oil input port being used for connecting to an oil pump, and the oil output port being used for connecting to a clutch;

[0008] A first valve core, the first valve core can slide relative to the first valve body and has a left position and a right position, the first throttle oil channel is configured to connect the input oil port and the output oil port when the first valve core is located in the left position and the right position; the second throttle oil channel is configured to reach a maximum opening when the first valve core is located in the right position and connect the input oil port and the output oil port, and when the first valve core moves from the right position to the left position, the opening of the second throttle oil channel gradually decreases to zero.

[0009] As a preferred technical solution of the speed change valve group, the flow rate of the second throttle oil passage when it is at its maximum opening is not greater than the flow rate of the first throttle oil passage.

[0010] As a preferred technical solution for the speed change valve group, the ratio of the flow rate of the second throttle oil passage when it is at its maximum opening to the flow rate of the first throttle oil passage is not greater than 0.5.

[0011] As an optimal technical solution for the speed change valve group, the speed change valve group also includes an adjusting member movably connected to the first valve body, and the moving direction of the adjusting member relative to the first valve body is the same as the sliding direction of the first valve core relative to the first valve body. When the first valve core is located in the right position, the first valve core abuts against the adjusting member, and there is a gap between the first valve core and the first valve body, and the gap connects the input oil port and the output oil port, and the gap forms the second throttling oil channel.

[0012] As an optimal technical solution for the speed change valve group, the first valve body is further provided with a second signal oil port and a third signal oil port, the second signal oil port is connected to the input oil port, and the third signal oil port is connected to the output oil port, the hydraulic oil in the second signal oil port is used to drive the first valve core to move to the right position, and the hydraulic oil in the third signal oil port is used to drive the first valve core to move to the left position, and the effective area of ​​the hydraulic oil in the third signal oil port and the first valve core is larger than the effective area of ​​the hydraulic oil in the second signal oil port and the first valve core.

[0013] As a preferred technical solution of the speed-changing valve group, the speed-changing valve group further includes a second control valve, and the second control valve includes:

[0014] a second valve body, the second valve body being provided with an oil inlet and an oil outlet, the oil outlet being communicated with the oil tank, and the oil inlet being selectively connected to the oil pump;

[0015] The second valve core can slide relative to the second valve body and has a first position and a second position. When the first valve core is located in the left position, the second valve core is located in the first position, and the oil inlet and the oil outlet are disconnected; when the first valve core is located in the right position, the second valve core is located in the second position, and the oil inlet and the oil outlet are connected.

[0016] As an optimal technical solution for the speed change valve group, the first valve body is also provided with an oil filling port, a pressure relief port and a connecting port, and the second valve body is also provided with a first signal port. The hydraulic oil in the first signal port is used to drive the second valve core to move to the first position, the connecting port is connected to the first signal port, the pressure relief port is connected to the oil tank, and the oil filling port is connected to the output port. When the first valve core is in the left position, the oil filling port is connected to the connecting port, and the pressure relief port is blocked; when the first valve core is in the right position, the oil filling port is connected to the pressure relief port, and the oil filling port is blocked.

[0017] As an optimal technical solution of the speed-changing valve group, the speed-changing valve group further includes a sequence valve, and the sequence valve is arranged in the connecting pipeline between the oil inlet and the oil pump.

[0018] As a preferred technical solution of the speed change valve group, the speed change valve group further includes a spring arranged between the sequence valve and the second control valve, the spring is used to drive the second valve core to move to the second position, and the sequence valve includes:

[0019] a third valve body, the third valve body being provided with an oil inlet interface, an oil outlet interface and a fourth signal oil port, the oil inlet interface being connected to an oil pump, the oil outlet interface being connected to the oil inlet, and the fourth signal oil port being connected to the oil inlet interface;

[0020] The third valve core is slidingly located in the third valve body, the force exerted by the hydraulic oil in the fourth signal oil port on the third valve core is opposite to the direction of the force exerted by the spring on the valve core, and when the difference between the force exerted by the hydraulic oil in the fourth signal oil port on the third valve core and the force exerted by the spring on the valve core is greater than a set value, the sequential valve opens.

[0021] On the other hand, the present invention provides an engineering machine comprising the speed change valve group in any of the above solutions.

[0022] The beneficial effects of the present invention are:

[0023] The present invention provides a speed change valve group and engineering machinery, the speed change valve group includes a first control valve, the first control valve includes a first valve body and a first valve core, the first valve body is provided with an input oil port and an output oil port, the first valve body is further provided with a first throttle oil passage and a second throttle oil passage, the input oil port is used to connect an oil pump, and the output oil port is used to connect a clutch; the first valve core can slide relative to the first valve body and has a left position and a right position, the first throttle oil passage is configured to connect the input oil port and the output oil port when the first valve core is in the left position and the right position; the second throttle oil passage is configured to reach a maximum opening when the first valve core is in the right position and connect the input oil port and the output oil port, when the first valve core moves from the right position to the left position, the opening of the second throttle oil passage gradually decreases to zero, so that when it is necessary to fill the clutch with oil, the first valve core can be placed in the right position, at this time, the clutch is filled with oil simultaneously through the first throttle oil passage and the second throttle oil passage, which can effectively improve instantaneous pressure shock and avoid pressure mutation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The structure of the speed change valve group in the embodiment of the present invention is shown as follows Figure 1 (the first valve core is in the right position, and the second valve core is in the second position);

[0025] Figure 2 The structure of the speed change valve group in the embodiment of the present invention is shown as follows Figure 2 (The first valve core is in the left position, and the second valve core is in the first position).

[0026] In the picture:

[0027] 1. First control valve; 11. Input oil port; 12. Output oil port; 13. First throttle oil passage; 14. Second throttle oil passage; 15. Second signal oil port; 16. Third signal oil port; 17. Oil filling port; 18. Pressure relief port; 19. Connecting oil port;

[0028] 2. Second control valve; 21. Oil inlet; 22. Oil outlet; 23. First signal oil port;

[0029] 3. Sequence valve; 31. Oil inlet port; 32. Oil outlet port; 33. Fourth signal oil port;

[0030] 4. Spring. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0033] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0034] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0035] like Figure 1 and Figure 2 As shown, this embodiment provides a speed change valve group, which is used for shift control of engineering machinery. The speed change valve group includes a first control valve 1, a second control valve 2 and a sequence valve 3.

[0036] The first control valve 1 comprises a first valve body and a first valve core. The first valve body is provided with an oil input port 11 and an oil output port 12. The first valve body is also provided with a first throttle oil passage 13 and a second throttle oil passage 14. The oil input port 11 is connected to the oil pump, and the oil output port 12 is connected to the clutch. The first valve core can slide relative to the first valve body and has a left position and a right position. The first throttle oil passage 13 is configured to connect the oil input port 11 and the oil output port 12 when the first valve core is in the left position or the right position. The second throttle oil passage 14 is configured to open to its maximum when the first valve core is in the right position, connecting the oil input port 11 and the oil output port 12. As the first valve core moves from the right position to the left position, the opening of the second throttle oil passage 14 gradually decreases to zero. When the clutch needs to be filled with oil, the first valve core is in the right position. At this time, the clutch is filled with oil simultaneously through the first throttle oil passage 13 and the second throttle oil passage 14, which effectively reduces transient pressure shocks and avoids sudden pressure changes.

[0037] Optionally, the flow rate of the second throttle oil passage 14 at its maximum opening is not greater than the flow rate of the first throttle oil passage 13. Specifically, in this embodiment, the ratio of the flow rate of the second throttle oil passage 14 at its maximum opening to the flow rate of the first throttle oil passage 13 is not greater than 0.5. The ratio of the flow rate of the second throttle oil passage 14 at its maximum opening to the flow rate of the first throttle oil passage 13 can be set according to the specific flow rate requirements of different clutches. For example, the ratio of the flow rate of the second throttle oil passage 14 at its maximum opening to the flow rate of the first throttle oil passage 13 can be 0.1, 0.15, 0.2, 0.3, 0.35, 0.4, or 0.45.

[0038] Optionally, the speed change valve assembly further includes an adjusting member (not shown in the accompanying drawings) movably connected to the first valve body. The adjusting member's movement relative to the first valve body is the same as the sliding direction of the first valve core relative to the first valve body. When the first valve core is in the right position, the first valve core abuts the adjusting member, and a gap is defined between the first valve core and the first valve body. The gap connects the input oil port 11 and the output oil port 12, forming a second throttle oil passage 14. With this arrangement, the flow rate of the second throttle oil passage 14 at its maximum opening can be varied by adjusting the position of the adjusting member relative to the first valve body, thereby adapting to the different flow requirements of different clutches and providing a wide range of applicability. Preferably, the adjusting member is threadedly connected to the first valve body, which facilitates operation.

[0039] Optionally, the first valve body is further provided with a second signal oil port 15 and a third signal oil port 16, the second signal oil port 15 is connected to the input oil port 11, and the third signal oil port 16 is connected to the output oil port 12, the hydraulic oil in the second signal oil port 15 is used to drive the first valve core to move to the right position, and the hydraulic oil in the third signal oil port 16 is used to drive the first valve core to move to the left position, and the effective area of ​​the hydraulic oil in the third signal oil port 16 and the first valve core is larger than the effective area of ​​the hydraulic oil in the second signal oil port 15 and the first valve core. Among them, when the oil pump is started, the oil pressure of the hydraulic oil in the second signal oil port 15 is equal to the oil pressure of the input oil port 11 of the first control valve 1, and the oil pressure of the third signal oil port 16 is equal to the oil pressure of the output oil port 12 of the first control valve 1. When the oil flows through the first control valve 1, it will inevitably be reduced in pressure by the throttling oil channel. Although the effective area of ​​the hydraulic oil in the third signal oil port 16 and the first valve core is larger than the effective area of ​​the hydraulic oil in the second signal oil port 15 and the first valve core, the hydraulic oil in the second signal oil port 15 is significantly larger than the hydraulic oil in the third signal oil port 16. The oil pressure of the hydraulic oil in the third signal oil port 16, thereby the hydraulic oil in the second signal oil port 15 can drive the first valve core to move instantaneously to the right position to flush the clutch. When the oil is full, the pressure difference on both sides of the throttle oil channel gradually drops to zero. At this time, the oil pressure of the output oil port 12 and the input oil port 11 tend to be equal. Since the effective area of ​​the hydraulic oil in the third signal oil port 16 and the first valve core is larger than the effective area of ​​the hydraulic oil in the second signal oil port 15 and the first valve core, the hydraulic oil in the third signal oil port 16 can drive the first valve core to move instantaneously to the left position.

[0040] The second control valve 2 includes a second valve body and a second valve core. The second valve body is provided with an oil inlet 21 and an oil outlet 22. The oil outlet 22 is connected to the oil tank, and the oil inlet 21 is used for selective connection with the oil pump. The second valve core can slide relative to the second valve body and has a first position and a second position. When the first valve core is in the left position, the second valve core is in the first position, and the oil inlet 21 and the oil outlet 22 are disconnected. When the first valve core is in the right position, the second valve core is in the second position, and the oil inlet 21 and the oil outlet 22 are connected. In this way, the oil pressure at the input oil port 11 can be selectively adjusted by the second control valve 2. The fact that the oil inlet 21 is used for selective connection with the oil pump means that the oil inlet 21 and the oil pump can be connected or disconnected.

[0041] Optionally, the first valve body is further provided with an oil filling port 17, a pressure relief port 18 and a connecting port 19, and the second valve body is further provided with a first signal oil port 23. The hydraulic oil in the first signal oil port 23 is used to drive the second valve core to move to the first position. The connecting port 19 is connected with the first signal oil port 23, the pressure relief port 18 is connected with the oil tank, and the oil filling port 17 is connected with the output oil port 12. When the first valve core is in the left position, the oil filling port 17 is connected with the connecting port 19, and the pressure relief port 18 is blocked; when the first valve core is in the right position, the oil filling port 17 is connected with the pressure relief port 18, and the oil filling port 17 is blocked. With such an arrangement, the second valve core can switch its position as the position of the first valve core switches, and when the first valve core is in the right position, the oil pressure of the first signal oil port 23 can be unloaded to make the second valve core in the right position. At this time, the hydraulic oil in the first signal oil port 23 flows back to the oil tank, and the output oil port 12 can realize low-pressure and rapid oil filling of the clutch; when the first valve core is in the left position, the first signal oil port 23 can be filled with oil to maintain the second valve core in the first position. At this time, the oil pressure in the first signal oil port 23 gradually increases to increase the oil pressure of the clutch.

[0042] Optionally, the speed change valve group further includes a sequence valve 3, which is arranged in the connecting pipeline between the oil inlet 21 and the oil pump. In this embodiment, the sequence valve is used to control the selective connection between the oil inlet 21 and the oil pump. Specifically, when the oil pressure at the input oil port 11 of the first control valve 1 is higher than the set pressure, the sequence valve 3 opens. It should be noted that when the first valve core is in the right position, the pressure at the input oil port 11 is low and lower than the set oil pressure. At this time, it is used to fill the clutch with low pressure. When the first valve core is in the left position, the pressure at the input oil port 11 can gradually increase to above the set pressure.

[0043] Optionally, the speed change valve group also includes a spring 4 arranged between the sequence valve 3 and the second control valve 2, and the spring 4 is used to drive the second valve core to move to the second position. The sequence valve 3 includes a third valve body and a third valve core. The third valve body is provided with an oil inlet interface 31, an oil outlet interface 32 and a fourth signal oil port 33. The oil inlet interface 31 is connected for connecting to the oil pump, the oil outlet interface 32 is connected to the oil inlet 21, and the fourth signal oil port 33 is connected to the oil inlet interface 31; the third valve core slides in the third valve body, and the hydraulic oil in the fourth signal oil port 33 exerts a force on the third valve core in an opposite direction to the force exerted on the valve core by the spring 4, and when the difference between the force exerted on the third valve core by the hydraulic oil in the fourth signal oil port 33 and the force exerted on the valve core by the spring 4 is greater than the set value, the sequence valve 3 opens. Specifically, when the first valve core is in the right position, the pressure of the fourth signal oil port 33 is equal to the pressure of the input oil port 11. At this time, the force provided by the spring 4 to the third valve core is much greater than the force provided by the hydraulic oil in the fourth signal oil port 33 to the third valve core, and the third valve core disconnects the oil inlet interface 31 and the oil outlet interface 32; conversely, when the first valve core is in the left position and the oil pressure of the fourth signal oil port 33 is increased to above the set pressure, the force provided by the hydraulic oil in the fourth signal oil port 33 to the third valve core will be greater than the force provided by the spring 4 to the third valve core, and the third valve core is driven to connect the oil inlet interface 31 and the oil outlet interface 32.

[0044] This embodiment also provides an engineering machine, including the speed change valve group in the above solution.

[0045] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A speed change valve group, characterized in that: The invention comprises a first control valve (1), wherein the first control valve (1) comprises: a first valve body, the first valve body being provided with an input oil port (11) and an output oil port (12), the first valve body also being provided with a first throttle oil passage (13) and a second throttle oil passage (14), the input oil port (11) being used for connecting to an oil pump, and the output oil port (12) being used for connecting to a clutch; a first valve core, the first valve core being capable of sliding relative to the first valve body and having a left position and a right position, the first throttle oil passage (13) being configured to connect the input oil port (11) and the output oil port (12) when the first valve core is in the left position and the right position; the second throttle oil passage (14) being configured to reach a maximum opening when the first valve core is in the right position and connect the input oil port (11) and the output oil port (12), and when the first valve core moves from the right position to the left position, the opening of the second throttle oil passage (14) gradually decreases to zero; The first valve body is further provided with a second signal oil port (15) and a third signal oil port (16), the second signal oil port (15) being communicated with the input oil port (11), and the third signal oil port (16) being communicated with the output oil port (12), the hydraulic oil in the second signal oil port (15) being used to drive the first valve core to move toward the right position, and the hydraulic oil in the third signal oil port (16) being used to drive the first valve core to move toward the left position, and the action area between the hydraulic oil in the third signal oil port (16) and the first valve core is larger than the action area between the hydraulic oil in the second signal oil port (15) and the first valve core.

2. The speed change valve assembly according to claim 1, characterized in that: The flow rate of the second throttling oil passage (14) when it is at its maximum opening is not greater than the flow rate of the first throttling oil passage (13).

3. The speed change valve assembly according to claim 2, characterized in that: The ratio of the flow rate of the second throttle oil passage (14) when it is at its maximum opening to the flow rate of the first throttle oil passage (13) is not greater than 0.

5.

4. The speed change valve assembly according to claim 2, characterized in that: The speed change valve group further includes an adjusting member movably connected to the first valve body, and the movable direction of the adjusting member relative to the first valve body is the same as the sliding direction of the first valve core relative to the first valve body. When the first valve core is located in the right position, the first valve core abuts against the adjusting member, and a gap exists between the first valve core and the first valve body, the gap communicating with the input oil port (11) and the output oil port (12), and the gap forms the second throttling oil passage (14).

5. The speed change valve assembly according to any one of claims 1 to 4, characterized in that: The speed change valve group further comprises a second control valve (2), wherein the second control valve (2) comprises: A second valve body, the second valve body being provided with an oil inlet (21) and an oil outlet (22), the oil outlet (22) being in communication with the oil tank, and the oil inlet (21) being used for selective connection with an oil pump; The second valve core is capable of sliding relative to the second valve body and has a first position and a second position. When the first valve core is located at the left position, the second valve core is located at the first position, and the oil inlet (21) and the oil outlet (22) are disconnected; when the first valve core is located at the right position, the second valve core is located at the second position, and the oil inlet (21) and the oil outlet (22) are connected.

6. The speed change valve assembly according to claim 5, characterized in that: The first valve body is further provided with an oil filling port (17), a pressure relief port (18) and a connecting port (19), and the second valve body is further provided with a first signal port (23). The hydraulic oil of the first signal port (23) is used to drive the second valve core to move toward the first position. The connecting port (19) is connected to the first signal port (23), the pressure relief port (18) is connected to the oil tank, and the oil filling port (17) is connected to the output port (12). When the first valve core is located in the left position, the oil filling port (17) is connected to the connecting port (19), and the pressure relief port (18) is blocked; when the first valve core is located in the right position, the oil filling port (17) is connected to the pressure relief port (18), and the oil filling port (17) is blocked.

7. The speed change valve assembly according to claim 5, characterized in that: The speed change valve group further comprises a sequence valve (3), and the sequence valve (3) is arranged in the connecting pipeline between the oil inlet (21) and the oil pump.

8. The speed change valve assembly according to claim 7, characterized in that: The speed change valve group further includes a spring (4) arranged between the sequence valve (3) and the second control valve (2), the spring (4) being used to drive the second valve core to move toward the second position, and the sequence valve (3) includes: A third valve body, the third valve body being provided with an oil inlet interface (31), an oil outlet interface (32) and a fourth signal oil port (33), the oil inlet interface (31) being connected to an oil pump, the oil outlet interface (32) being connected to the oil inlet (21), and the fourth signal oil port (33) being connected to the oil inlet interface (31); The third valve core is slidably located in the third valve body, and the force exerted by the hydraulic oil in the fourth signal oil port (33) on the third valve core is opposite to the force exerted by the spring (4) on the valve core, and when the difference between the force exerted by the hydraulic oil in the fourth signal oil port (33) on the third valve core and the force exerted by the spring (4) on the valve core is greater than a set value, the sequence valve (3) opens.

9. An engineering machine, characterized in that: The invention comprises the speed change valve group according to any one of claims 1 to 8.

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