CN209164221U - 2D PWM Mechanism - Google Patents

Abstract

Two-dimentional pulsewidth modulation mechanism, transmission shaft shift fork stir spool by roll wheel assembly, slide axially while so that spool is rotated in valve pocket, valve core rotation with slide axially relatively independent, zero-bit spring is mounted among spool and transmission shaft and in compressive state；Transmission shaft one end connects transmission mechanism；Spool is located in the central through hole of valve pocket；It is control oil groove respectively from left to right that the outer circle of valve pocket, which is set there are four annular groove, goes out oil groove, oil-feed tank and oil-recovery tank, controls on oil groove, goes out on oil groove, is uniformly provided with several identical radial holes on oil-feed tank, on oil-recovery tank；Center spool is axially arranged with center flow channels, and the first circular through hole and the second circular through hole are linked up by center spool runner；It is respectively left triangle oil-distribution port, right triangle oil-distribution port that the staggered triangle oil-distribution port of two column is provided on the second shoulder of spool, and vertex is in the same plane and the plane is perpendicular to valve core axis.

Description

2D PWM Mechanism

technical field

The utility model belongs to the technical field of fluid transmission and control, and relates to a two-dimensional pressure feedback flow distribution mechanism, in particular to a two-dimensional pulse width modulation mechanism.

Background technique

During the working process of the plunger pump, the plunger reciprocates in the cylinder, resulting in the change of the working volume of the seal to achieve oil absorption and oil discharge. Each plunger cavity of the axial plunger pump periodically switches back and forth between the oil suction port and the oil discharge port, and the switching process of the oil port needs to be realized by the flow distribution mechanism of the pump.

According to the distribution mode, the axial piston pump is mainly divided into valve distribution and end distribution. The valve distribution is mainly realized by the one-way valve. Two one-way valves are installed at the oil inlet and outlet of the pump respectively. The plunger cavity opens the one-way valve of the corresponding oil port in the oil suction and discharge stage, so as to realize the oil suction and discharge. The valve distribution method does not require cylinder rotation, and is generally used in single-piston pumps. The one-way valve has a certain opening pressure, and the response has a certain hysteresis, which makes the self-priming ability of the pump poor, which is easy to cause cavitation and limit the speed of the pump. The end face distribution is the main distribution method of the plunger pump at present. This distribution method requires the cylinder block of the plunger pump to rotate so that the plunger cavity and the oil suction window and the oil discharge window on the distribution plate are alternately connected for oil suction and discharge. The cylinder of the plunger pump has multiple plunger holes, the diameter of the cylinder is large, and the high pressure and high speed require higher design requirements for the key friction pair of the cylinder and the valve plate; in order to reduce the start-up time of the motor, increase the The response speed of the system, the traditional method is to install the unloading valve at the outlet of the hydraulic pump, which increases the complexity of the design and processing of the mechanical system and the control system.

The existing two-dimensional (2D) pumps all use two-dimensional unloading valves, two-dimensional pressure-stabilizing valves and other valve groups to realize the adjustment of pressure and flow.

SUMMARY OF THE INVENTION

In order to overcome the problems of poor self-priming, low rotational speed, large cylinder diameter, high technical requirements for friction pairs, and complex mechanical systems and control systems caused by valve distribution and end-face distribution of the plunger pump, and also in order to overcome the existing two-dimensional ( 2D) The shortage of the pump to adjust the flow distribution mode of multiple hydraulic valves, the utility model provides a novel and compact structure, small size, light weight, simple transmission, no friction pair, easy to achieve high pressure and high speed, and realizes the realization of the double degree of freedom structure of the valve core. The two-dimensional pressure feedback flow distribution mechanism for flow distribution is a two-dimensional pulse width modulation mechanism. The utility model not only solves the shortcomings and deficiencies of the flow distribution of the plunger pump, but also facilitates and optimizes the flow distribution mechanism of the two-dimensional (2D) pump. At the same time, the unloading valve at the outlet of the hydraulic pump can be omitted. Zero pressure start, suitable for distribution of hydraulic pumps, motors, etc.

The technical scheme adopted by the utility model is as follows:

The two-dimensional pulse width modulation mechanism is characterized in that it includes a transmission shaft, a zero spring, a roller shaft, a left roller assembly, a right roller assembly, a front concentric ring, a valve core, a valve sleeve, a rear concentric ring, and a valve core plug. . The drive shaft shift fork and the roller assembly cooperate to move the valve core through the roller shaft, so that the valve core rotates circumferentially in the valve sleeve and slides axially at the same time. The valve core rotation and axial sliding are relatively independent. The front concentric ring and the rear concentric ring They are respectively fixed on both ends of the valve sleeve, and the zero-position spring is installed between the valve core and the transmission shaft and is in a compressed state.

One end of the transmission shaft is a cylindrical end, which is connected to the transmission mechanism; the other end of the transmission shaft is in the shape of a door frame and is connected with two U-shaped shifting forks. The valve core rotates in the circumferential direction and slides axially at the same time; there is a circular groove on the axial middle end face of the transmission shaft, which is used to fix the zero-position spring.

The two flat end surfaces of the zero-position spring are respectively fixed at the circular groove of the transmission shaft and the stepped shaft at the left end of the valve core. The zero-position spring is in a compressed state at the beginning and during the working process, so as to ensure that the valve core is at the rightmost end in the initial state and keep the valve core. zero.

The roller shaft is a stepped cylindrical shaft with a shoulder in the middle, and the diameter of the middle cylinder is larger than the diameter of the two cylinders; the middle shoulder shaft is inserted into the cylindrical hole at the left end of the valve core and fixedly connected, and the shafts at both ends are respectively inserted into the center of the left roller assembly and the right roller assembly. round holes and fixed.

The right roller assembly has the same structure as the left roller assembly, including a bearing sleeve and a deep groove ball bearing. The outside of the bearing sleeve is spherical, the inside is a round hole, and both ends are flat end surfaces. The inner hole of the bearing sleeve is sleeved outside the deep groove ball bearing. Round and fixed, the spherical surface of the bearing sleeve is matched with the cylindrical surface of the U-shaped shift fork of the transmission shaft.

The front concentric ring is in the shape of a circular ring, the two ends are flat, the outer circle of the front concentric ring is fixedly connected with the valve sleeve, and the inner hole is sleeved on the left end shaft of the valve core.

The rear concentric ring is a circular ring, the two ends are flat, the inner hole has a stepped hole to provide a space for the second circular through hole of the valve core, the outer circle of the rear concentric ring is fixedly connected with the valve sleeve, and the inner hole is sleeved on the valve. on the right shaft of the core.

The inner hole of the valve sleeve is a central through hole, which is matched with the valve core, and the two ends are respectively provided with a front stepped hole and a rear stepped hole, which are respectively fixed with the front concentric ring and the rear concentric ring; the outer circle of the valve sleeve is provided with four annular From left to right, the grooves are the control oil groove, the oil discharge groove, the oil input groove and the oil return groove. The control oil groove is evenly provided with several identical radial control oil holes, and the oil discharge groove is evenly provided with several identical radial oil discharge holes. The oil inlet groove is evenly provided with a number of identical radial rhombus distribution windows, the apex of the diamond distribution window is in the same plane and the plane is perpendicular to the axis of the valve core, and the oil return groove is evenly provided with a number of the same radial oil return holes .

The leftmost end of the valve core has a stepped shaft, which is used to install the zero-position spring. The right side of the stepped shaft is provided with a circular through hole of the roller shaft, which is fixedly connected with the roller shaft to transmit torque to the valve core to make the valve core rotate; the valve core There are three shoulders, a first shoulder, a second shoulder and a third shoulder in sequence from left to right, and the spool shaft between the first shoulder and the second shoulder is radially provided with a first circular through hole , the spool shaft near the right end face of the third shoulder is radially provided with a second circular through hole, the center of the spool is axially provided with a central flow channel, the central flow channel port is blocked with a spool screw, and the first circular through hole is provided. The hole and the second circular through hole are communicated through the center flow channel of the valve core; there are two rows of staggered triangular distribution windows on the second shoulder of the valve core, which are the left triangular distribution window and the right triangular distribution window, and their vertices are in the same plane. And the plane is perpendicular to the spool axis.

Preferably, the outer spherical surface of the bearing sleeve and the U-shaped shift fork of the transmission shaft are in clearance fit, and are in unilateral contact under force to realize forward and reverse rotation. The transmission shaft drives the valve core through the left roller assembly, the right roller assembly and the roller shaft. Rotating, the valve core slides axially under the action of hydraulic pressure, which drives the bearing sleeve to roll axially on the U-shaped shift fork of the transmission shaft.

Preferably, the outer circles of the front concentric ring and the rear concentric ring are respectively fixed in the front stepped hole and the rear stepped hole on both ends of the valve sleeve, and the inner hole of the front concentric ring is sleeved on the left end shaft of the valve core, which is a gap seal, and the rear The inner hole of the concentric ring is sleeved on the shaft at the right end of the valve core to seal the gap.

Preferably, the valve core is rotatably arranged in the valve sleeve, the front concentric ring and the first shoulder of the valve core seal the inner cavity of the valve sleeve to form a control cavity, and the control cavity communicates with the control oil groove through the control oil hole, and the control The oil groove is connected to the control pressure oil; the first shoulder and the second shoulder of the spool seal the inner cavity of the valve sleeve to form a high-pressure cavity. The oil inlet groove is connected to the high pressure oil of the hydraulic pump, and the oil outlet groove is connected to the system oil circuit; the second shoulder and the third shoulder of the valve core seal the inner cavity of the valve sleeve to form a low pressure cavity, and the low pressure cavity communicates with the oil return tank through the oil return hole, and the return The oil tank is connected to the low-pressure oil tank; the third shoulder of the valve core and the rear concentric ring seal the inner cavity of the valve sleeve to form a feedback cavity, and the feedback cavity passes through the first circular through hole of the valve core, the central flow channel, and the second circular through hole. The high-pressure chambers communicate with each other, and the two chambers have the same pressure; the valve sleeve control oil tank, oil outlet tank, oil inlet tank and oil return tank do not communicate with each other outside the valve sleeve. There are two rows of staggered triangular distribution windows on the second shoulder of the valve core, which are respectively the left triangle distribution window and the right triangle distribution window. The inner sleeve rotates at a constant speed while sliding axially under the action of hydraulic pressure, so that the left triangular distribution window and right triangular distribution window of the spool change the distribution time ratio of the valve sleeve diamond distribution window respectively, thereby changing the oil flow to realize the flow distribution.

The specific working process is as follows:

Driven by the drive shaft, the valve core rotates at a constant speed, and the two rows of staggered triangular distribution windows on the second shoulder of the valve core and the diamond-shaped distribution window of the valve sleeve groove rotate relative to each other in the circumferential direction; the liquid pressure in the control cavity acts on the valve core The annular area on the left end face of the first shoulder produces an axial rightward thrust on the spool, and the liquid pressure in the feedback cavity acts on the annular area on the right end face of the third shoulder of the spool to produce an axial leftward thrust on the spool. The compression of the zero spring produces an axial rightward thrust on the valve core. If the resultant force of the axial rightward thrust on the valve core and the spring force is greater than the axial leftward thrust, the valve core slides axially to the right. The resultant force of the right thrust and the spring force is smaller than the axial left thrust, and the spool slides axially to the left. When the forces at both ends of the valve core are balanced, the valve core stays at a certain working position of the valve sleeve. As the valve core rotates, the left triangular distribution window of the valve core, the right triangle distribution window and the valve sleeve diamond distribution window alternately communicate and change periodically. Due to the large number of the left and right triangular distribution windows of the valve core and the diamond distribution windows of the valve sleeve, the gradient of the valve port area is very large, so that the opening of the valve port has little effect on the flow rate through the valve port, and the flow rate through the valve port can be considered as a The amount that is independent of the valve opening and only related to the opening time of the valve, that is, the time required for the left triangular distribution window of the spool and the right triangular distribution window to alternately sweep through the diamond-shaped distribution window of the valve sleeve in any period respectively accounts for the total amount of time. The ratio of time is the distribution ratio of the inlet oil flow, and the flow distribution of the oil outlet flow and the oil return flow is carried out according to this ratio.

When the valve core is at the zero position, the valve core is at the rightmost end in the valve sleeve, the valve sleeve oil inlet groove and the oil outlet groove are connected to the maximum, and the oil inlet groove and the oil return groove are not communicated, so as to ensure that the high pressure oil of the pump flows into the system before the pressure is established. , so that the system can quickly build up pressure until the system pressure flow is stable and the spool is in a balanced state. When the valve core is at the leftmost end in the valve sleeve, the valve sleeve inlet oil groove and the oil outlet groove are not connected, the oil inlet groove and the oil return groove are connected to the maximum, the high pressure oil of the pump all flows into the oil tank, and the hydraulic pump is in the unloading state; at this time, if the hydraulic pressure The pump stops working and the system is in the state of maintaining pressure. When the hydraulic pump is started with pressure again, the oil outlet of the valve sleeve communicates directly with the oil return trough, that is, the oil outlet of the hydraulic pump communicates directly with the oil tank, and the hydraulic pressure can be realized under the condition of system pressure maintaining. The pump starts at almost zero load.

When the control chamber pressure remains unchanged, the system pressure does not change, and the system demand flow changes, the system pressure changes slightly, resulting in corresponding changes in the pressure of the high-pressure chamber and the feedback chamber. Sliding in the direction of the valve core, and the axial sliding of the spool causes the left triangular distribution window and the right triangular distribution window of the spool to alternately sweep through the diamond-shaped distribution window of the valve sleeve respectively. Corresponding changes occur, the flow entering the system changes accordingly, and the pressure in the feedback chamber changes accordingly until the valve core reaches a new equilibrium state; when the system pressure needs to be changed, the control chamber pressure is changed, and the valve core acts on the axial resultant force When the lower axis slides, the left triangular distribution window and right triangular distribution window of the spool alternately sweep through the diamond-shaped distribution window of the valve sleeve respectively. The flow of the system changes accordingly, and the pressure of the feedback chamber changes accordingly. When the axial resultant force of the valve core is balanced again, the system pressure rises and the valve core reaches a new equilibrium state.

The axial sliding of the spool changes the proportion of the distribution time, thereby changing the oil flow into the hydraulic system. Therefore, using this structure to adjust the system flow can be regarded as pulse width modulation controlled by the position of the valve core. Because the valve core rotates very fast, and there are many triangular distribution windows on the circumference of the valve core, and corresponding diamond distribution windows on the circumference of the valve sleeve, the frequency of the pulse width modulation is very high, and the pressure pulsation and flow pulsation are almost reflected in the system. not come out.

The dual-degree-of-freedom structure of the valve core means that the valve core can slide axially while rotating in the circumferential direction, and the circumferential rotation and axial sliding of the valve core are independent of each other; the rotation of the valve core is caused by the external torque transmitted to the valve core through the transmission shaft. Yes, the axial sliding of the valve core is caused by the different forces on both ends of the valve core.

The axial direction refers to the direction in which the central axis of the spool is located or parallel to the central axis of the spool; the radial direction refers to the direction perpendicular to the central axis of the spool; the circumferential direction refers to the direction of the spool around the center The direction in which the axis rotates.

The time required for the left triangular distribution window of the valve core and the right triangular distribution window to sweep through the diamond-shaped distribution window of the valve sleeve alternately respectively refers to the left triangular distribution window of the valve core and the right triangle distribution window of the valve sleeve respectively in any cycle. Coincidence time from opening to closing.

The beneficial effects of the present utility model are embodied in:

1. Drawing on the traditional spool valve structure, it adopts a new flow distribution method with double free structure of the valve core. The structure is simple and the performance is reliable. There is pressure feedback in the axial direction of the valve core, which can adjust the system pressure and output flow at the same time.

2. The rotation of the valve core makes the frequency of pulse width modulation very high, which greatly improves the pressure and flow pulsation in the system.

3. It replaces the previous two-dimensional (2D) pump valve group to control the flow, reduce the adjustment mechanism and simplify the design.

4. Compared with the end face distribution of the traditional plunger pump, the friction pair structure is cancelled, the wear is reduced and the efficiency is improved.

5. The hydraulic pump can be started with almost zero load in the high pressure system.

Description of drawings

FIG. 1 is a schematic structural diagram of a two-dimensional pulse width modulation mechanism.

Figure 2 is a schematic diagram of the structure of the valve sleeve.

FIG. 2a is a C-C cross-sectional view of FIG. 2 .

Figure 3 is a schematic diagram of the structure of the valve core.

FIG. 3a is a D-D cross-sectional view of FIG. 3 .

Figure 4 is a schematic diagram of the structure of the transmission shaft.

FIG. 5 is a schematic structural diagram of the right roller assembly.

FIG. 6 is a schematic view of the structure of the roller shaft.

Figure 7a is a schematic diagram of the principle of the valve sleeve matching flow window.

Figure 7b is a schematic diagram of the principle of the valve core distribution window.

Figure 7c is a schematic diagram of the flow distribution principle when the spool is in the neutral position.

Figure 7d is a schematic diagram of the flow distribution principle when the spool moves down.

Detailed ways

The technical solution of the present utility model is further described below with reference to FIGS. 1 to 7d .

The two-dimensional pulse width modulation mechanism is characterized in that: a transmission shaft 1, a zero spring 2, a roller shaft 3, a left roller assembly 4, a right roller assembly 5, a front concentric ring 6, a valve sleeve 7, a valve core 8, The rear concentric ring 9 and the valve core screw plug 10 are composed. The fork of the transmission shaft 1 cooperates with the left roller assembly 4 and the right roller assembly 5 to toggle the valve core 8 through the roller shaft 3, so that the valve core 8 rotates circumferentially in the valve sleeve 7 and slides axially at the same time. The axial sliding is relatively independent, the front concentric ring 6 and the rear concentric ring 9 are respectively fixed on both ends of the valve sleeve 7, and the zero-position spring 2 is installed between the valve core 8 and the transmission shaft 1 and is in a compressed state.

One end of the transmission shaft 1 is a cylindrical end, which is connected to the transmission mechanism to make the transmission shaft 1 rotate; the other end of the transmission shaft 1 is in the shape of a door frame, connecting two U-shaped forks, and the fork surface is an incomplete cylindrical surface track extending axially. , cooperate with the left roller assembly 4 and the right roller assembly 5 to make the valve core 8 rotate in the circumferential direction and slide axially at the same time; there is a circular groove on the axial middle end face of the transmission shaft 1 for fixing the zero position spring 2 .

The two flat end surfaces of the zero-position spring 2 are respectively fixed at the groove of the transmission shaft 1 and the stepped shaft at the left end of the valve core 8. The zero-position spring 2 is in a compressed state both initially and during the working process, ensuring that the valve core 8 is at the rightmost end in the initial state. , keep the spool 8 at zero position.

The roller shaft 3 is a stepped cylindrical shaft with a shoulder in the middle, and the diameter of the middle cylinder is larger than the diameter of the two cylinders; the middle shoulder shaft is inserted into the cylindrical hole at the left end of the valve core 8 and fixedly connected, and the shafts at both ends are respectively inserted into the left roller assembly 4, right The central circular hole of the roller assembly 5 is fixed.

The right roller assembly 5 has exactly the same structure as the left roller assembly 4, including a bearing sleeve 51 and a deep groove ball bearing 52. The outside of the bearing sleeve 51 is a spherical surface, the inside is a round hole, and both ends are flat end surfaces. The inner hole of the bearing sleeve 51 is sleeved. The deep groove ball bearing 52 is externally circled and fixedly connected, and the spherical surface of the bearing sleeve 51 is matched with the cylindrical surface of the U-shaped shifting fork of the transmission shaft 1 .

The front concentric ring 6 is a circular ring with flat surfaces at both ends.

The rear concentric ring 9 is annular, and the two end faces are flat surfaces. There is a stepped hole in the inner hole to provide an escape space for the second circular through hole B2 of the valve core 8. The outer circle of the rear concentric ring 9 is fixedly connected with the valve sleeve 7. The inner hole is sleeved on the shaft at the right end of the valve core 8 .

The inner hole of the valve sleeve 7 is a central through hole, which cooperates with the valve core 8, and has a front stepped hole and a rear stepped hole at both ends, which are respectively fixed with the front concentric ring 6 and the rear concentric ring 9; the outer circle is provided with four From left to right, the annular grooves are respectively the control oil groove K, the oil discharge groove A, the oil input groove P and the oil return groove T. The control oil groove K is evenly provided with a number of control oil holes k with the same radial direction, and the oil discharge groove A is evenly provided with a number of control oil holes k. The same radial oil outlet hole a and the oil inlet groove P are evenly provided with several identical radial rhombus distribution windows p. The apex of the rhombus distribution window p is in the same plane and the plane is perpendicular to the spool axis, and the oil return groove T Several identical radial oil return holes t1 are evenly arranged on the upper part.

The leftmost end of the valve core 8 has a stepped shaft for installing the zero position spring 2, and the right side of the stepped shaft has a circular through hole for the roller shaft, which is fixedly connected with the roller shaft 3 to transmit torque to the valve core 8 to make the valve core 8 Rotation; the spool 8 has three shoulders from left to right with a first shoulder 81, a second shoulder 82 and a third shoulder 83, the spool shaft between the first shoulder 81 and the second shoulder 82 A first circular through hole B1 is arranged radially, a second circular through hole B2 is arranged radially on the spool shaft close to the right end face of the third shoulder 83, and a central flow channel B is arranged in the center axis of the spool 8. The flow channel mouth is blocked by the valve core plug 10, the first circular through hole B1 and the second circular through hole B2 communicate through the central flow channel B of the valve core 8; the second shoulder 82 of the valve core 8 has two staggered rows The triangular distribution windows are respectively the left triangular distribution window p1 and the right triangular distribution window p2, the vertices of which are in the same plane and the plane is perpendicular to the valve core axis.

The outer spherical surface of the bearing sleeve 51 is in clearance fit with the U-shaped shift fork of the transmission shaft 1. When the force is applied, the unilateral contact can realize forward and reverse rotation. The transmission shaft 1 passes through the left roller assembly 4, the right roller assembly 5 and the roller shaft. 3. Drive the valve core 8 to rotate, the valve core 8 slides axially under the action of hydraulic pressure, and drives the bearing sleeve 51 to roll axially on the U-shaped shift fork of the transmission shaft 1.

The outer circles of the front concentric ring 6 and the rear concentric ring 9 are respectively fixed in the front stepped hole and the rear stepped hole on the two ends of the valve sleeve 7, and the inner hole of the front concentric ring 6 is sleeved on the left end shaft of the valve core 8, which is a gap seal. , the inner hole of the rear concentric ring 9 is sleeved on the right end shaft of the valve core 8 to seal the gap.

The valve core 8 is rotatably arranged in the valve sleeve 7. The front concentric ring 6 and the first shoulder 81 of the valve core seal the inner cavity of the valve sleeve 7 to form a control chamber K1, which is connected to the control chamber K1 through the control oil hole k. The control oil tank K communicates, and the control oil tank K is connected to the control pressure oil; the first shoulder 81 and the second shoulder 82 of the valve core 8 seal the inner cavity of the valve sleeve 7 to form a high-pressure chamber A1, and the high-pressure chamber A1 passes through the oil outlet hole a and The oil outlet tank A communicates with the oil inlet tank P through the diamond-shaped distribution window p. The oil inlet tank P is connected to the high pressure oil of the hydraulic pump, and the oil outlet tank A is connected to the system oil circuit; the second shoulder 82 and the third shoulder 83 of the valve core 8 connect the valve. The inner cavity of the sleeve 7 is sealed to form a low-pressure cavity T1. The low-pressure cavity T1 communicates with the oil return tank T through the oil return hole t1, and the oil return tank T is connected to the low-pressure oil tank; the third shoulder 83 of the valve core 8 and the rear concentric ring 9 connect the valve sleeve 7 The inner cavity is sealed to form a feedback cavity A2, and the feedback cavity A2 communicates with the high-pressure cavity A1 through the first circular through hole B1, the central flow channel B, and the second circular through hole B2 of the valve core 8, and the pressures of the two cavities are the same; The sleeve control oil tank K, the oil outlet tank A, the oil inlet tank P and the oil return tank T do not communicate with each other outside the valve sleeve. There are two rows of staggered triangular distribution windows on the second shoulder 82 of the valve core 8, which are respectively the left triangular distribution window p1 and the right triangular distribution window p2. The diamond-shaped distribution window p of the valve sleeve 7 is located on the second shoulder 82 of the valve core 8. On the movement track, the valve core 8 rotates at a constant speed in the valve sleeve 7 and slides axially under the action of hydraulic pressure, so that the left triangular distribution window p1 and the right triangular distribution window p2 of the valve core 8 are distributed with the diamond distribution window p of the valve sleeve 7 respectively. The time proportion changes, thereby changing the oil flow to realize the flow distribution.

The working principle of this embodiment:

The valve core 8 rotates at a constant speed under the drive of the transmission shaft 1, and the staggered left triangular distribution window p1 and right triangular distribution window p2 provided on the second shoulder 82 of the valve core 8 are circumferentially opposite to the diamond-shaped distribution window p of the valve sleeve 7. Rotate; the liquid pressure in the control chamber K1 acts on the annular area S1 of the left end face of the first shoulder 81 of the valve core 8 to generate an axial rightward thrust on the valve core 8, and the liquid pressure in the feedback volume A2 acts on the third valve core 8. The annular area S2 on the right end face of the shoulder 83 generates an axial leftward thrust on the valve core 8, and the zero-adjusting spring 2 is compressed to generate an axial rightward thrust on the valve core 8. If the axial rightward thrust on the valve core 8 is the same as The resultant force of the spring force is greater than the axial leftward thrust, that is, the resultant force at the left end of the valve core 8 is greater than the right end resultant force, and the valve core 8 slides axially to the right. Thrust, that is, the resultant force at the left end of the valve core 8 is less than the resultant force at the right end, and the valve core 8 slides axially to the left. The resultant force at the right end keeps the spool 8 in its axial position and is in a balanced state.

In order to illustrate the flow distribution principle of the two-dimensional pulse width modulation mechanism, the left triangular distribution window p1 of the valve core 8, the right triangular distribution window p2, and the rhombic distribution window p of the valve sleeve 7 are expanded circumferentially, and simplified as a schematic diagram, as shown in Fig. 7a and Fig. 7b, Fig. 7c, Fig. 7d. The left and right linear motion of the valve core in the schematic diagram represents the circumferential rotation of the valve core in the schematic diagram, and the vertical movement of the valve core up and down in the schematic diagram represents the axial sliding of the valve core in the schematic diagram. In Figure 7a and Figure 7b, P0 is the oil inlet, which is equivalent to the oil inlet tank P, A0 is the oil outlet, which is equivalent to the oil outlet tank A, and T0 is the oil return port, which is equivalent to the oil return tank T.

The valve core 8 can freely rotate and slide axially in the valve sleeve 7. As the valve core 8 rotates, the left triangular distribution window p1 and the right triangular distribution window p2 of the valve core 8 communicate alternately with the valve sleeve 7 diamond distribution window p in a periodic manner. Due to the large number of the left and right triangular distribution windows p1 and p2 of the valve core 8 and the diamond distribution window p of the valve sleeve 7, the valve port area gradient is very large, so that the valve opening has little effect on the flow through the valve port. The flow rate of the port can be regarded as a quantity that is independent of the opening of the valve port but only related to the opening time of the valve port, that is, the left triangular distribution window p1 and the right triangular distribution window p2 of the spool 8 alternately sweep across the valve sleeve in any cycle. 7. The ratio of the time required by the diamond-shaped flow distribution window p to the total time, which is the distribution ratio of the oil inlet flow, and the flow distribution of the oil outlet flow and the oil return flow is carried out according to this ratio;

As shown in Fig. 7c and Fig. 7d, the ordinate is the flow rate Q of the oil inlet P0, the abscissa time t, within any cycle time Δt, the left triangular distribution window p1 of the spool 8 sweeps the valve sleeve 7 diamond distribution window p required Time Δt1, the time Δt2 required for the right triangular distribution window p2 of the spool 8 to sweep through the diamond distribution window p of the valve sleeve 7, the flow rate of the oil outlet A0 is Q·Δt1/Δt, and the flow rate of the oil return port T0 is Q·Δt2/Δt . Comparing Figure 7c and Figure 7d, it can be seen that the axial sliding of the spool changes the proportion of Δt1 and Δt2, thereby changing the oil flow into the hydraulic system. Therefore, the method of using this structure to adjust the system flow can be regarded as Pulse width modulation controlled by spool position. Because the valve core 8 rotates very fast, and there are many left and right triangular distribution windows p1 and p2 on the circumference of the valve core 8, and the corresponding diamond distribution window p is set on the circumference of the valve sleeve 7, the frequency of the pulse width modulation is very high, and the pressure pulsation And flow pulsation is barely reflected in the system.

When the spool 8 is at the zero position, the spool 8 is at the rightmost end in the valve sleeve 7, the oil inlet port P0 and the oil outlet port A0 are in maximum communication, and the oil inlet port P0 and the oil return port T0 are not communicated to ensure that the system is building up the pressure Before the hydraulic pump, all the high-pressure oil of the hydraulic pump flows into the system, so that the system can quickly build up the pressure, and the valve core is in a balanced state until the system pressure and flow are stable. When the valve core 8 is at the leftmost end in the valve sleeve 7, the oil inlet port P0 and the oil outlet port A0 do not communicate, the oil inlet port P0 communicates with the oil return port T0 at the maximum, and the high pressure oil of the hydraulic pump all flows into the oil tank, and the hydraulic pump is in Unloading state; at this time, if the hydraulic pump stops working, the system is in a pressure-holding state. When the hydraulic pump starts with pressure again, the oil inlet P0 communicates directly with the oil return port T0, that is, the oil outlet of the hydraulic pump directly communicates with the oil tank Communication, the hydraulic pump can be started with almost zero load under the system pressure maintaining state.

If the control pressure remains unchanged, the system pressure remains unchanged, and the system demand flow changes, the system pressure also changes slightly. When the system demand flow increases and the system pressure decreases, the pressure of the high-pressure oil chamber A1 and the feedback chamber A2 decreases, the pressure of the control chamber K1 remains unchanged, the balance state of the valve core 8 is broken, and the resultant force at the left end of the valve core 8 is greater than that at the right end. The spool 8 slides axially to the right. At this time, the opening of the oil inlet P0 and the oil outlet A0 increases, the opening of the oil inlet P0 and the oil return port T0 decreases, and the left triangular distribution window p1 of the spool 8 sweeps over the valve sleeve 7. The time of the diamond-shaped distribution window p becomes longer, and the right triangular distribution window p2 of the spool 8 sweeps over the valve sleeve. 7. The time of the diamond-shaped distribution window p becomes shorter, and the flow of the oil outlet A0 becomes larger to supply energy to the system until the system pressure rises and returns to its original state. When there is pressure, the pressure of the high-pressure chamber A1 and the feedback chamber A2 rises and returns to the original pressure, the resultant force at the left end of the valve core 8 is equal to the resultant force at the right end, and the valve core 8 reaches the equilibrium state again. On the contrary, when the system demand flow decreases and the system pressure increases, the pressure of the high-pressure oil chamber A1 and the feedback chamber A2 increases, the pressure of the control chamber K1 remains unchanged, the balance state of the valve core 8 is broken, and the left end of the valve core 8 The resultant force is less than the resultant force at the right end, and the spool 8 slides axially to the left. At this time, the opening of the oil inlet port P0 and the oil outlet port A0 decreases, the opening degree of the oil inlet port P0 and the oil return port T0 increases, and the valve spool 8 is distributed in a left triangle. Window p1 sweeps through the valve sleeve 7 diamond-shaped distribution window p time becomes shorter, the spool 8 right triangular distribution window p2 sweeps through the valve sleeve 7 diamond distribution window p time becomes longer, and the flow rate of return port T0 increases, so that more oil flows back to the tank , the flow of the oil outlet A0 becomes smaller, the flow into the system becomes smaller until the system pressure decreases and returns to the original pressure, the pressure of the high-pressure chamber A1 and the feedback chamber A2 decreases and returns to the original pressure, the resultant force of the left end of the spool 8 is equal to the resultant force of the right end, The spool 8 is in equilibrium again.

If you need to change the system pressure, you only need to change the pressure value of the control oil port to break the original balance state of the valve core and establish a new balance state. When the pressure of the control chamber K1 increases, the resultant force at the left end of the spool 8 is greater than the resultant force at the right end, and the spool 8 slides axially to the right. At this time, the opening of the oil inlet P0 and the oil outlet A0 becomes larger, and the oil inlet P0 and the return The opening of the oil port T0 becomes smaller (until it is completely closed), and the pressure of the oil outlet A0 increases with the increase of the oil flow into the system, until the resultant force at both ends of the spool 8 is equal again, the spool reaches a new equilibrium state . When the pressure of the control chamber K1 decreases, the resultant force at the left end of the spool 8 is smaller than the resultant force at the right end, and the spool 8 slides axially to the left. At this time, the opening of the oil inlet port P0 and the oil outlet port A0 becomes smaller (until it is completely closed), and the oil inlet The opening of the port P0 and the oil return port T0 becomes larger, and the pressure of the oil outlet A0 decreases with the decrease of the oil flow into the system. When the resultant force at both ends of the spool 8 is equal again, the spool reaches a new equilibrium state.

By reasonably setting the size relationship between the annular area S1 of the left end face of the first shoulder 81 of the valve core 8, the annular area S2 of the right end face of the third shoulder 83 of the valve core 8, and the stiffness of the zero-position spring, the outlet of the two-dimensional pulse width modulation mechanism can be established. The proportional relationship between the pressure and the control oil port pressure, so that the outlet pressure value can be adjusted by changing the value of the control oil port pressure, so as to achieve the adjustment of the system pressure and flow.

The content described in the embodiments of the present specification is only an enumeration of the realization forms of the inventive concept, and the protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments, and the protection scope of the present invention also extends to the present invention. Equivalent technical means that can be conceived by those skilled in the art according to the inventive concept.

Claims (4)

1. Two-dimensional pulse width modulation mechanism, it is characterized in that: comprise drive shaft, zero spring, roller shaft, left roller assembly, right roller assembly, front concentric ring, valve core, valve sleeve, rear concentric ring, valve core screw plug ;The drive shaft fork and the roller assembly cooperate to move the valve core through the roller shaft, so that the valve core rotates circumferentially in the valve sleeve and slides axially at the same time, the valve core rotation and axial sliding are relatively independent, the front concentric ring and the rear concentric ring The rings are respectively fixed on both ends of the valve sleeve, and the zero-position spring is installed between the valve core and the transmission shaft and is in a compressed state; One end of the transmission shaft is a cylindrical end, which is connected to the transmission mechanism; the other end of the transmission shaft is in the shape of a door frame and is connected with two U-shaped shifting forks. assembly, so that the valve core rotates in the circumferential direction and slides axially at the same time; there is a circular groove on the axial middle end face of the transmission shaft, which is used to fix the zero-position spring; The two flat end surfaces of the zero-position spring are respectively fixed at the circular groove of the transmission shaft and the stepped shaft at the left end of the valve core. The zero-position spring is in a compressed state at the beginning and during the working process, so as to ensure that the valve core is at the rightmost end in the initial state and keep the valve core. zero; The roller shaft is a stepped cylindrical shaft with a shoulder in the middle, and the diameter of the middle cylinder is larger than the diameter of the two cylinders; the middle shoulder shaft is inserted into the cylindrical hole at the left end of the valve core and fixedly connected, and the shafts at both ends are respectively inserted into the center of the left roller assembly and the right roller assembly. round holes and fixed connection; The right roller assembly has the same structure as the left roller assembly, including a bearing sleeve and a deep groove ball bearing. The outside of the bearing sleeve is spherical, the inside is a round hole, and both ends are flat end surfaces. The inner hole of the bearing sleeve is sleeved outside the deep groove ball bearing. Round and fixed, the spherical surface of the bearing sleeve is matched with the cylindrical surface of the U-shaped shift fork of the transmission shaft; The front concentric ring is a circular ring, the two ends are flat, the outer circle of the front concentric ring is fixedly connected with the valve sleeve, and the inner hole is sleeved on the left end shaft of the valve core; The rear concentric ring is a circular ring, the two ends are flat, the inner hole has a stepped hole to provide a space for the second circular through hole of the valve core, the outer circle of the rear concentric ring is fixedly connected with the valve sleeve, and the inner hole is sleeved on the valve. On the right end shaft of the core; The inner hole of the valve sleeve is a central through hole, which is matched with the valve core, and the two ends are respectively provided with a front stepped hole and a rear stepped hole, which are respectively fixed with the front concentric ring and the rear concentric ring; the outer circle of the valve sleeve is provided with four annular From left to right, the grooves are the control oil groove, the oil discharge groove, the oil input groove and the oil return groove. The control oil groove is evenly provided with several identical radial control oil holes, and the oil discharge groove is evenly provided with several identical radial oil discharge holes. The oil inlet groove is evenly provided with a number of identical radial rhombus distribution windows, the apex of the diamond distribution window is in the same plane and the plane is perpendicular to the axis of the valve core, and the oil return groove is evenly provided with a number of the same radial oil return holes ; The leftmost end of the valve core has a stepped shaft, which is used to install the zero-position spring. The right side of the stepped shaft is provided with a circular through hole of the roller shaft, which is fixedly connected with the roller shaft to transmit torque to the valve core to make the valve core rotate; the valve core There are three shoulders, a first shoulder, a second shoulder and a third shoulder in sequence from left to right, and the spool shaft between the first shoulder and the second shoulder is radially provided with a first circular through hole , the spool shaft near the right end face of the third shoulder is radially provided with a second circular through hole, the center of the spool is axially provided with a central flow channel, the central flow channel port is blocked with a spool screw, and the first circular through hole is provided. The hole and the second circular through hole are communicated through the center flow channel of the valve core; there are two rows of staggered triangular distribution windows on the second shoulder of the valve core, which are the left triangular distribution window and the right triangular distribution window, and their vertices are in the same plane. And the plane is perpendicular to the spool axis. 2. The two-dimensional pulse width modulation mechanism according to claim 1, characterized in that: the outer spherical surface of the bearing sleeve and the U-shaped shift fork of the transmission shaft are in clearance fit, and they are in unilateral contact when being stressed, and can realize forward and reverse rotation. , The drive shaft drives the valve core to rotate through the left roller assembly, the right roller assembly and the roller shaft, the valve core slides axially under the action of hydraulic pressure, and drives the bearing sleeve to roll axially on the U-shaped shift fork of the transmission shaft. 3. The two-dimensional pulse width modulation mechanism according to claim 1, wherein the outer circles of the front concentric ring and the rear concentric ring are respectively fixed in the front stepped hole and the rear stepped hole on both ends of the valve sleeve, and the front The inner hole of the concentric ring is sleeved on the left end shaft of the valve core, which is a gap seal, and the inner hole of the rear concentric ring is sleeved on the right end shaft of the valve core, which is a gap seal. 4 . The two-dimensional pulse width modulation mechanism according to claim 1 , wherein the valve core is rotatably arranged in the valve sleeve, and the front concentric ring and the first shoulder of the valve core seal the inner cavity of the valve sleeve to form a seal. 5 . The control cavity is communicated with the control oil tank through the control oil hole, and the control oil tank is connected to the control pressure oil; the first shoulder and the second shoulder of the valve core seal the inner cavity of the valve sleeve to form a high-pressure cavity, and the high-pressure cavity passes through the outlet. The oil hole communicates with the oil outlet groove, and at the same time communicates with the oil inlet groove through the diamond-shaped distribution window. The oil inlet groove communicates with the high pressure oil of the hydraulic pump, and the oil outlet groove communicates with the system oil circuit; the second shoulder and the third shoulder of the valve core seal the inner cavity of the valve sleeve to form Low-pressure chamber, the low-pressure chamber communicates with the oil return tank through the oil return hole, and the oil return groove leads to the low-pressure fuel tank; the third shoulder of the valve core and the rear concentric ring seal the inner cavity of the valve sleeve to form a feedback chamber, and the feedback chamber passes through the valve core. A circular through hole, a central flow channel, and a second circular through hole communicate with the high-pressure chamber, and the pressures of the two chambers are the same; the valve sleeve control oil groove, oil outlet groove, oil inlet groove and oil return groove are not communicated with each other outside the valve sleeve; the valve core There are two rows of staggered triangular distribution windows on the second shoulder, which are the left triangular distribution window and the right triangular distribution window. The valve sleeve diamond distribution window is located on the movement trajectory of the second shoulder of the valve core, and the valve core is in the valve sleeve. While rotating at a constant speed, it slides axially under the action of hydraulic pressure, so that the left triangular distribution window and right triangular distribution window of the spool change the distribution time ratio of the valve sleeve diamond distribution window respectively, thereby changing the oil flow to realize the flow distribution.