A low constant speed running system for rail transit vehicles

Abstract

A low-constant-speed running system for rail transit vehicles includes a running gear, a hydraulic motor, a motor valve assembly, a two-position six-way solenoid directional valve, a speed control valve, and a hydraulic oil source supplying oil to the hydraulic motor. This running hydraulic system serves as a second power source to drive the running gear. A first power source, powered by other vehicle components, also drives the running gear. The second power source is connected in parallel with the first power source and, together with the first power source, acts on the axle gearbox to drive the running gear and propel the vehicle. The hydraulic motor of the running hydraulic system is mounted on the input port of the axle gearbox, which has a clutch function connected to the hydraulic motor. The running system of this invention features good speed stability, a large speed difference between low and very low speeds, and linear adjustment across a wide speed range.

Description

Technical Field

[0001] This invention relates to a rail transit vehicle, and more specifically to a power transmission control system for a rail transit vehicle. Background Technology

[0002] Currently, when rail transit vehicles in my country operate under both high-speed and low-speed conditions, they are often driven by a fully hydraulic system or by feedback control through electric or hydraulic transmissions. However, a fully hydraulic system makes it difficult to guarantee safety during high-speed operation, while feedback control through electric or hydraulic transmissions makes it difficult to guarantee control accuracy at low speeds, especially on long downhill slopes where runaway is likely to occur, affecting vehicle safety.

[0003] One of the first and second axles of a rail transit vehicle is located near the end beam of the vehicle. The layout of the running gear, where the axle gearbox is located, is compact. How to design a running system in a limited space to overcome the above problems has become a challenge. Summary of the Invention

[0004] This invention proposes a hydraulic system for driving rail transit vehicles at low constant speeds. The hydraulic motor is mounted on the axle gearbox using a clutch mechanism. The hydraulic system employs a load-balancing valve to maintain vehicle speed stability under reverse running loads. A speed control valve regulates the motor speed and maintains a constant speed. A two-position six-way solenoid directional valve switches between two running speeds, thus meeting some special operational requirements of rail transit vehicles. This hydraulic system features good speed stability, a large speed difference between low and very low speeds, and linear adjustment across a wide speed range.

[0005] The technical solution of this invention is: a low constant speed running system for rail transit vehicles, comprising a running gear and a running hydraulic system consisting of a hydraulic motor, a motor valve group, a two-position six-way solenoid directional valve, and a speed control valve as a second power source for driving the running gear, and further comprising a first power source for driving the running gear; the first power source is connected to an axle gearbox via a drive shaft; the running gear includes an axle gearbox, an axle, and wheelsets; the motor valve group is a hydraulic valve group that installs a load balancing valve and a solenoid directional valve; The hydraulic motor is installed at the input port of the axle gearbox and provides rotational driving force. The axle gearbox has a clutch function for connecting to the hydraulic motor: the hydraulic motor is connected to the drive shaft in the axle gearbox via a clutch device or shift fork, realizing the transmission or disengagement of the rotational driving force output by the hydraulic motor to the axle gearbox; the hydraulic oil source controls the rotation of the hydraulic motor after passing through the speed control valve, the two-position six-way solenoid directional valve, and the motor valve group; the clutch device or shift fork of the axle gearbox is operated to switch gears, so that the hydraulic motor engages or disengages from the drive shaft of the axle gearbox; when the hydraulic motor engages with the drive shaft of the axle gearbox, the hydraulic motor drives the axle gearbox to make the vehicle move; When the vehicle needs to operate at a low constant speed, the axle gearbox, through gear shifting, disconnects the transmission route for driving the running gear from the primary power source connected to the axle gearbox via the drive shaft. The clutch device or shift fork of the axle gearbox is operated to shift gears, engaging the hydraulic motor with the drive shaft of the axle gearbox. The speed control valve provides speed control with two flow adjustment ranges: low speed and ultra-low speed. A two-position six-way solenoid valve is operated to switch between the two oil circuits. If low speed control is selected, the flow output of the speed control valve is adjusted and input to the hydraulic motor via the motor valve assembly, driving the axle gearbox to move the vehicle.

[0006] The inlet and outlet oil routes of the hydraulic motor are controlled by the solenoid directional valve of the motor valve assembly. The solenoid directional valve is operated to switch the direction of rotation of the hydraulic motor.

[0007] Under the action of the load counterbalancing valve of the motor valve group, the reverse load pressure is maintained for the hydraulic motor drive, so that the vehicle's travel speed is kept stable because the pressure change of the reverse load of the travel system caused by downhill or operation will not cause the hydraulic motor speed to change.

[0008] The speed control valve is an electro-proportional flow control valve with pressure compensation, or an electro-proportional multi-way directional valve with pressure compensation. Under the pressure compensation of the speed control valve, the hydraulic flow of the system supplied to the hydraulic motor through the speed control valve remains constant without being affected by changes in vehicle travel resistance, allowing the vehicle to travel at a constant speed.

[0009] The two-position six-way solenoid directional valve is a hydraulic solenoid directional valve that selects and switches between two hydraulic oil circuits through electromagnetic control, providing hydraulic motors with two flow rate options: low speed and very low speed.

[0010] The second power source also includes a hydraulic oil source for supplying oil to the hydraulic motor.

[0011] This invention employs a novel hydraulic power transmission scheme, utilizing limited space to expand functional modules. The transmission or disengagement of the rotational driving force output by the hydraulic motor to the axle gearbox is achieved directly at the transfer input port of the expanded axle gearbox via a clutch device or gear shifting fork. Through a rationally designed low-speed constant-speed hydraulic system, employing a speed control strategy for the low-speed travel motor and a power switching control strategy for the high-low dual-power transmission system, this invention caters to the high-precision speed control requirements of onboard work devices at different gear levels.

[0012] This invention proposes a low-constant-speed traveling system that, based on a first power source acting on the axle gearbox, adds a hydraulic motor as a second power source for hydraulic transmission. This achieves speed control with a two-stage flow rate adjustment range providing a speed difference of 8:1 or higher between the large and small speeds of the hydraulic motor. The low-constant-speed traveling system features good speed stability and linear adjustment across a wide speed variation range. Through a clutch connection, the low-constant-speed traveling system can flexibly switch power with the first power source, meeting the high-precision speed control requirements of onboard operating devices in rail transit vehicles at different speeds. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the present invention; In the diagram: 1. Hydraulic oil source; 2. System return oil; 3. Speed ​​control valve; 4. Two-position six-way solenoid directional valve; 5. Motor valve group; 6. Hydraulic motor; 7. Axle gearbox; 8. First power source. Detailed Implementation

[0014] The present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0015] like Figure 1 As shown, the first power source 8 is connected to the axle gearbox 7 via a drive shaft to drive the running gear, which includes the axle gearbox 7, axles, wheelsets, and other components. The hydraulic motor 6 is mounted on the extended input port of the axle gearbox, and the axle gearbox 7 has a clutch function for connecting to the hydraulic motor 6. The hydraulic oil source 1, serving as the second power source, drives the hydraulic motor 6 to rotate via the speed control valve 3, the two-position six-way solenoid directional valve 4, and the motor valve group 5. The axle gearbox 11 is driven by the clutch device of the axle gearbox 7 or by gear shifting via the shift fork, thus enabling the vehicle to move.

[0016] The motor valve assembly 5 preferably consists of a hydraulic valve assembly with a load balancing valve and a solenoid directional valve, which provides reverse load pressure to maintain the drive of the hydraulic motor 6, so that the vehicle's travel speed remains stable because the pressure change of the reverse load of the travel system caused by downhill or operation does not cause the speed change of the hydraulic motor 6. The inlet and outlet oil routes of the hydraulic motor 6 are controlled by the solenoid directional valve on the motor valve assembly 5, and the solenoid directional valve is operated to switch the direction of rotation of the hydraulic motor 6.

[0017] The speed control valve 3 provides speed control for the hydraulic motor 6 with two flow adjustment ranges: low speed and ultra-low speed. The speed control valve 6 is preferably an electro-proportional flow control valve with pressure compensation, but it can also be an electro-proportional multi-way directional valve with pressure compensation. The pressure compensation is a disclosed technology, featuring a differential pressure reducing valve that maintains a constant pressure difference across the valve orifice, thus ensuring that the system flow rate is unaffected by load changes. The electro-proportional flow control valve is a hydraulic valve that controls the flow rate through the valve orifice proportionally to the magnitude of the control current by electrically controlling the valve orifice size.

[0018] The two-position six-way solenoid directional valve 4 is a hydraulic solenoid directional valve that selects and switches between two hydraulic oil circuits through electromagnetic control, providing the hydraulic motor 6 with two speed ranges: low speed and very low speed.

[0019] like Figure 1 As shown, the specific control strategy in practical applications is as follows: when the vehicle needs to operate at a low constant speed, the axle gearbox 7 switches gears, disconnecting the transmission route used to drive the running gear from the first power source 8 via the drive shaft. The clutch device or shift fork of the axle gearbox 7 is then operated to switch gears, engaging the hydraulic motor 6 with the drive shaft of the axle gearbox. The speed control valve 3 provides speed control with two flow adjustment ranges: low speed and ultra-low speed. The two-position six-way solenoid directional valve 4 is operated to switch between the two oil circuits. If low speed control is selected, the flow output of the speed control valve 3 is adjusted and input to the hydraulic motor 6 via the motor valve group 5, driving the axle gearbox 7 to move the vehicle. Under the action of the load counterbalancing valve of the motor valve group 5, the vehicle's travel speed remains stable because the pressure change of the reverse load of the travel system caused by downhill or operation does not cause the speed change of the hydraulic motor 6. Under the action of the pressure compensation of the speed control valve 3, the hydraulic flow of the system supplied to the hydraulic motor 6 through the speed control valve 3 remains constant without being affected by the change of the vehicle's travel resistance, thus enabling the vehicle to travel at a constant speed.

[0020] The above description, in conjunction with the accompanying drawings, is merely a description of one specific embodiment of the present invention and does not limit the technical solution of the present invention to this. All equivalent changes or external modifications made based on the spirit and principle of the present invention should fall within the protection scope of the present invention.

Claims

1. A low constant speed running system for rail transit vehicles, characterized in that: The traveling hydraulic system, consisting of a running section, a hydraulic motor (6), a motor valve group (5), a two-position six-way solenoid directional valve (4), and a speed control valve (3), serves as the second power source for driving the running section. It also includes a first power source (8) for driving the running section. The first power source (8) is connected to the axle gearbox (7) via a drive shaft. The running section includes the axle gearbox (7), axles, and wheelsets. The motor valve group (5) is a hydraulic valve group equipped with a load-balancing valve and a solenoid directional valve. The speed control valve (3) is an electro-proportional flow control valve with pressure compensation or an electro-proportional multi-way directional valve with pressure compensation. Under the pressure compensation of the speed control valve (3), the system hydraulic flow supplied to the hydraulic motor (6) through the speed control valve (3) remains constant without being affected by changes in vehicle running resistance, allowing the vehicle to travel at a constant speed. The hydraulic motor (6) is installed in the input port of the axle gearbox (7) and provides rotational driving force. The hydraulic motor (6) is connected to the drive shaft in the axle gearbox (7) via a clutch device or shift fork, so that the rotational driving force output by the hydraulic motor (6) can be transmitted to or disengaged from the axle gearbox (7). The hydraulic oil source (1) controls the rotation of the hydraulic motor (6) after passing through the speed control valve (3), the two-position six-way solenoid directional valve (4), and the motor valve group (5). The clutch device or shift fork of the axle gearbox (7) is operated to switch gears, so that the hydraulic motor (6) engages or disengages from the drive shaft of the axle gearbox (7). When the hydraulic motor (6) engages with the drive shaft of the axle gearbox (7), the hydraulic motor (6) drives the axle gearbox (7) to make the vehicle move. When the vehicle needs to travel at a low constant speed, the axle gearbox (7) switches gears to disconnect the transmission route of the first power source (8) connected to the axle gearbox (7) via the drive shaft to drive the running gear and make the vehicle travel. The clutch device or shift fork of the axle gearbox (7) is operated to switch gears, so that the hydraulic motor (6) engages with the drive shaft of the axle gearbox. The speed control valve (3) provides speed control with two flow adjustment ranges of low speed and ultra-low speed. The two-position six-way solenoid directional valve (4) is operated to switch between the two oil circuits. If the low speed control is selected, the flow output of the speed control valve (3) is adjusted and input to the hydraulic motor (6) through the motor valve group (5) to drive the axle gearbox (7) and make the vehicle travel.

2. The low constant speed running system for rail transit vehicles according to claim 1, characterized in that: The inlet and outlet oil routes of the hydraulic motor (6) are controlled by the solenoid directional valve of the motor valve group (5). The solenoid directional valve is operated to change the direction of rotation of the hydraulic motor (6).

3. The low constant speed running system for rail transit vehicles according to claim 1, characterized in that: Under the action of the load counterbalance valve of the motor valve group (5), the reverse load pressure is maintained for the hydraulic motor (6) drive, so that the vehicle travel speed is kept stable because the pressure change of the reverse load of the travel system caused by downhill or operation will not cause the speed change of the hydraulic motor (6).

4. The low constant speed running system for rail transit vehicles according to claim 1, characterized in that: The two-position six-way solenoid directional valve (4) is a hydraulic solenoid directional valve that selects and switches between two hydraulic oil circuits by electromagnetic control, providing two speed ranges of low speed and very low speed for the hydraulic motor (6).

5. The low constant speed running system for rail transit vehicles according to claim 1, characterized in that: The second power source also includes a hydraulic oil source for supplying oil to the hydraulic motor.

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