TWI608172B - Hydraulic drive - Google Patents

Description

Hydraulic drive

The invention relates to a hydraulic actuator for a hydraulic consumer according to the first reference of the patent application.

According to EP 1 387 090 A2, there is a known hydraulic drive of this type which is provided with a variable speed electric motor which in this case drives two constant speed pumps. At least one pump is activated/turned off depending on the actual kerometer pressure, wherein the pump preferably selectively switches rotation with a larger stroke volume. In this way, the motor drive is designed to have a low torque.

EP 0 805 922 B1 discloses a hydraulic pump control system for aircraft which uses a hydraulic pump with a variable displacement (stroke volume) which is driven by a variable speed motor. Here, the motor speed is adjusted such that when the system requirements are reduced, the rate of decrease is less than the rate at which the system increases as the system requirements increase. This means that, for example, when the pressure is required to decrease, the stroke volume of the pump is first reduced, and when the required pressure is increased, the motor speed is first increased.

Another prior art is EP 404 286 B1, in which an electric oil pressure drive unit is also mentioned, which uses an electric motor that can be operated in a variable speed manner to drive an adjustment pump. Here, the adjustment pump is adjusted to a position with a maximum stroke volume by means of a spring, and if the pressure in the oil pressure system rises above a certain pressure value, it is adjusted in this direction to the direction of the minimum stroke volume.

US 6,048,177 discloses an oil pressure system in which the pump is driven by an internal combustion engine.

Finally, DE 10 2007 007 005 A1 discloses an electric oil pressure control device having a variable displacement pump which is driven by a variable speed electric motor. To control the pump, a two-point regulator is provided. The pump switches to a maximum or minimum transport position and is switched relative to a pressure threshold that is above and below this value.

Starting from the above prior art, an object of the present invention is to provide a hydraulic actuator for a hydraulic system which is at least a variable medium (variable stroke volume) pressure medium (hydraulic pump) and a variable speed The drive motor is constructed in which the drive has better properties than the prior art. One purpose is to make the hydraulic drive cost-effective. Another purpose is to reduce the cost of conditioning technology. Finally, it is an object of the present invention to reduce the power of the drive motor, particularly by the "downsizing" principle, without compromising the functional safety of the downstream hydraulic system.

This object is achieved by a hydraulic actuator having the features of claim 1 of the patent application, and other advantageous features of the invention are found in the dependent claims.

Accordingly, the present invention relates to a hydraulic actuator for a hydraulic consuming or hydraulic system having a variable stroke volume pump for mechanically coupling a pump to a variable speed drive motor; A control means for adjusting the stroke volume of the pump, according to the invention, the pump is adjusted according to the torque.

In other words, the drive pump must not exceed a certain torque, as long as a torque (which is obtained by multiplying the system pressure by the stroke volume, we call it the pressure medium required for each revolution of the pump) even at the maximum stroke Below this certain torque, the torque does not have to be adjusted. If a pressure (which is measured by the load, or can be preset at the stop with a pressure valve during the acceleration process and during the load) is such that the product of the pressure multiplied by the stroke volume reaches this preset value, the pump turns to small The stroke volume direction is adjusted and the product of the pressure multiplied stroke volume remains at least constant.

In this case it is possible to drive the motor with a smaller maximum torque, so that the drive is less expensive overall and its operation is less economical due to the reduced power requirements of the motor.

The term "torque detection and/or measuring device" is used herein to refer to the actual torque load that the device is suitable for feeding back to the drive motor. For example, the device can be a torque sensor placed on the drive motor or its output shaft, or a current measuring device that measures the amount of current actually consumed by the motor and thereby determines its output torque. It is also possible to detect the actual pressure in the oil pressure system downstream of the pump and adjust or adjust the stroke volume so that the preset maximum torque is not exceeded.

In a particularly preferred manner, the "torque detection and/or measuring device" is a conventionally-adjusted torque regulator in which a valve piston of a "regulating valve" receives a spring force in an adjustment direction (it is pre- The maximum torque is set and in the other direction is generated by another force (which is caused by a piston of the pump pressure acting on a lever (this point is related to the stroke volume).

The drive motor is variable in speed, if the stroke volume of the pump is reduced accordingly Less, to limit the torque required by the motor, this will slow the movement caused by the oil pressure of one or several energy consuming devices (such as a reciprocating cylinder). If we want to maintain this movement, the speed of the drive motor can be increased when the stroke volume of the pump is reduced. Thus, the volume flow generated by the pump that is pivoted back is increased according to the rotational speed without increasing the output torque.

However, if the hydraulic consumer receives only one pressure at a stop when the pressure is increased, the rotational speed of the drive motor does not increase or even decrease.

By adjusting the pressure medium directly/indirectly according to the rotational speed, the power consumption of the motor can be kept below a substantially (as if) constant value, so that the motor can be designed to be smaller in its maximum possible power output.

The invention will be described in detail below with reference to the drawings in a preferred embodiment.

According to Figure 1, the left side is a conventional hydraulic actuator which uses two independently driven constant pumps, each driven by a motor which is itself variable (variable speed). This configuration is cumbersome and costly, and in addition to the large space requirements, this solution is not economical. The middle of Figure 1 is an improvement of the same conventional hydraulic actuator. This drive also uses two constant pumps, but they are driven together by a single motor. One of the constant motors can be selectively switched directly to an oil sump via a valve (here a 2/2 switching valve with an open and a blocked position) so that the pump is removed by the downstream hydraulic system. The motor can be unloaded.

The right side of the figure is a hydraulic actuator (1) of the present invention.

According to this, only a single pump (2) is provided, which is designed to have a variable stroke volume. For example, The pump (2) can be made into a swash plate pump, the slanting plate inclination can be changed continuously or in sections, and the detection end of the pump (2) is connected to a hydraulic system (4), for example, by an "action valve". (6) The configuration utilizes an energy consuming device (8) (here a piston cylinder unit).

The single stroke variable volume pump (2) is driven by a single (preferably variable speed) drive motor (10) (eg an electric motor) that is mechanically coupled to the pump (2) via a drive shaft .

Finally, a control unit (11) is provided to control the drive motor (10), at least one torque sensor and another sensor (for detecting the actual adjusted stroke volume of the pump (2) (inclination disc inclination) 〕 is connected to the control unit (all sensors are not shown). Here, the control unit (11) is programmed or programmable to cause the hydraulic actuator (1) to generate a predetermined (inputtable) consuming or system pressure and to maintain this pressure.

According to the invention, a smaller power drive motor (10) is constructed which allows the maximum output torque to be small, so when this maximum output torque is reached or when it is already large (for example, when the pressure in the hydraulic system rises) The variable volume pump (2) is moved back, in other words, its transport capacity is reduced, so that the actual output torque of the drive motor (10) is reduced. In this way, the pump (2) or its stroke volume is adjusted to be unaffected by the downstream oil. The pressure state of the pressure system affects the ground, the actual output torque of the motor (10) does not exceed or remain below a maximum torque value, and in an advantageous case, the output torque can remain substantially constant. In other words, it satisfies this formula: P × V = constant = T

Where: actual pressure in the P hydraulic system

Actual stroke volume of the V pump

The actual output torque of the T motor.

If the transport capacity of the pump (2) is moved back in this manner, the hydraulic pressure on the damper is lowered, or the sump is slowed by the hydraulic action. In order to avoid this, according to a preferred embodiment of the present invention, the drive motor (10) can be changed to a variable speed as needed, so that when the pump (2) has a reduced transport capacity, the motor (10) can be rotated to maintain the output. The torque is constant to maintain the actual consuming energy or kinetic energy speed required.

Regarding the control of such a pressure medium or a variable stroke pump (2), reference may be made to the piping diagram of Fig. 2, which shows a diagram of the pressure medium pump of the present invention. In the figure, there is a hydraulic actuator in a casing (12) having a cylinder drum (40), a drive shaft (22), a swash plate (43), and an outer pivot piston (75) (it Enclosing an adjustment chamber (101): a return spring (85) stopping at the outer pivoting piston (75), and an inner pivoting piston (76) (which encloses an adjustment chamber (102)) housing (12) There is a high pressure channel (103) and a low pressure (or suction) channel (104). The adjustment chamber (101) is connected to a high pressure channel (103) for a long time via a channel (105). A regulating valve (80) is constructed to the housing. (12) The regulating valve is composed of a "torque adjusting part valve" (106) and a "pressure regulating part valve" (107), which in a rest position passes through a first input end and its "regulated output end" A regulating output of the torque regulating portion valve (106) is connected to a control line (108), and the control line leads to an adjustment chamber (102) of the "internal pivoting piston" (76). The pressure regulating portion valve (107) The second input end is connected to the high pressure passage (103). Similarly, one input end of the torque adjustment portion valve (106) is connected to the high pressure passage (103), and the second input end of one of the torque adjustment portion valves (106) To the inside of the housing (12) Pressure groove) open put. One of the pressure regulating portion valves (107) "adjusting the piston" is subjected to the pressure of the high pressure line (103) to reduce the pivoting angle of the swash plate (43) and is biased in the opposite direction by an adjustable spring.

A two-arm lever (115) is supported in the housing (95) of the valve (80), a piston (116) is embedded in a lever arm, and the piston is guided in a housing of the reversing element, and The pressure in the high pressure passage (103) is supplied via the passage (105), the adjustment chamber (101) and the hole (92) in the outer pivot piston (75), and the distance of the fitting point is pivoted with the swash plate (43). The angle changes. The other arm of the lever (115) is located between one end of the adjustment piston (106) adjusting the piston and an adjustable spring (117), the spring (117) being at least substantially oppositely fitted on the lever arm, in addition, the moment The adjustment piston of the adjustment portion valve (106) is biased toward the lever arm by an adjustable spring (118) which is in contact with the spring (118) which is weaker than the spring (117). 115) a fixed moment is generated in one direction of the upper edge, and the high pressure in the passage (103) generates a moment by the action area of the piston (116) on the lever (115), which is resistant to the above fixed torque and externally pivoted The position of the piston (75) is generally related to the pivoting angle of the swashplate (43). At a given pressure, the torque generated by the two springs will remain balanced only at a certain pivot angle. When the pressure change breaks the balance, the valve piston of the torque adjustment portion valve (106) is moved out of its adjustment position, so that the pressure medium can flow to the adjustment chamber (102) or flow out of the adjustment chamber (102) until another pivot is reached. Up to the angle (at this pivoting angle, the torque on the lever (115) is again balanced).

Therefore, if the pressure of the hydraulic system is increased, the pressure in the pipeline (103) is increased, and according to Fig. 2, the valve piston of the torque regulating portion valve (106) is pulled to the right, so that the system pressure acts through the pipeline (108) to the inside. Pivot the piston" (76). It This reduces the inclination of the swash plate (43) until the torque of the lever arm (115) is balanced, so that the driving torque to be output from the motor to the shaft (22) can be kept constant.

(1)‧‧‧Hydraulic drive

(2) ‧‧ ‧ pump

(4) ‧‧‧Hydraulic system

(8) ‧‧‧ energy consuming devices

(10)‧‧‧Drive motor

(12) ‧‧‧Shell

(22)‧‧‧Drive shaft

(40) ‧‧‧Cylinder Drum

(43)‧‧‧Sloping disk

(75) ‧‧‧ external pivoting piston

(76) ‧‧‧ pivoting piston

(80)‧‧‧Regulators

(85)‧‧‧Return spring

(92) ‧‧‧ holes

(95) ‧‧‧Shell

(101) ‧ ‧ adjustment room

(102) ‧ ‧ adjustment room

(103)‧‧‧High-pressure passage

(104)‧‧‧Low pressure (suction) channel

(105) ‧‧‧ channels

(106)‧‧‧Torque adjustment part valve

(107)‧‧‧Pressure regulating part valve

(108)‧‧‧Control lines

(115) ‧ ‧ arms lever

(116) ‧‧‧Pistons

(117) ‧ ‧ spring

(118) ‧ ‧ spring

Figure 1 shows the opposite position: - one hydraulic drive according to the prior art, two individually driven pumps with a small stroke volume; - a hydraulic drive according to the prior art, with a permanent or a A switchable constant pump; a hydraulic actuator according to a preferred embodiment of the present invention, having a torque-controlled variable stroke volume pump and a variable speed drive.

Figure 2 is a hydraulic pressure adjustment/control means for a pressure medium (a pump having a variable stroke volume) according to the present invention.

(12) ‧‧‧Shell

(22)‧‧‧Drive shaft

(40) ‧‧‧Cylinder Drum

(43)‧‧‧Sloping disk

(75) ‧‧‧ external pivoting piston

(76) ‧‧‧ pivoting piston

(80)‧‧‧Regulators

(85)‧‧‧Return spring

(92) ‧‧‧ holes

(95) ‧‧‧Shell

(101) ‧ ‧ adjustment room

(102) ‧ ‧ adjustment room

(103)‧‧‧High-pressure passage

(104)‧‧‧Low pressure (suction) channel

(105) ‧‧‧ channels

(106)‧‧‧Torque adjustment part valve

(107)‧‧‧Pressure regulating part valve

(108)‧‧‧Control lines

(115) ‧ ‧ arms lever

(116) ‧‧‧Pistons

(117) ‧ ‧ spring

(118) ‧ ‧ spring

Claims (1)

A hydraulic actuator for a hydraulic damper (8) or a hydraulic system (4) having: a variable stroke pump (2) and a variable speed drive motor, the pump The variable speed drive motor (10) is mechanically coupled; the drive motor (10) is an electric motor; and has a control means (12) for adjusting the stroke volume of the pump (12), characterized by: a pump (2) A mechanical hydraulic torque regulator is provided, in the form of a torque regulating partial valve (106), wherein a valve piston of a regulating valve (80) is pressed by a spring (118) to a first adjustment The direction is pressed by another force to a second adjustment direction, the spring (118) presets a maximum torque, and the other force is a piston (116) biased by the pressure of the pump (2) in one arm a fitting point on the lever (115) is generated, the fitting point being related to the stroke volume of the variable volume pump (2), and wherein the variable speed drive motor (10) is dependent on the pump (2) The actual stroke volume is determined to be adjusted so that the hydraulic consumer (8) has a predetermined speed of movement.