JPH02238179A - Variable displacement pump - Google Patents

Abstract

PURPOSE:To change a pulsation pressure in a piston chamber so as to reduce production of noise by generating a control signal having a functional relation with a basic frequency of the pulsation pressure in the piston chamber, and controlling a fluid pressure in driving a stroke control member. CONSTITUTION:For a variable displacement pump where the stroke of a plurality of pistons 2 engaged freely reciprocally in a cylinder block 2 is controlled by a stroke control member of an inclined plate 5, the inclined plate 5 has its inclination angle adjusted by action of a bias cylinder 7 which applies a bias force to an operation cylinder 6 and the inclined plate 5 receiving a discharge fluid pressure. In this case, a control device 12 generates a control signal having a functional relation with the basic frequency of a pulsation pressure in a piston chamber relating to noise. A servo valve 13 is controlled by this control signal to control a fluid pressure, and a controlled fluid pressure is supplied to the bias cylinder 7 to control an inclination angle of the inclined plate 5.

Description

[Detailed description of the invention] Industrial application fields> Industrial application fields> This invention relates to a variable displacement pump.

BACKGROUND ART Conventionally, as a variable displacement pump designed to reduce noise, there is one described in Japanese Patent Laid-Open No. 54-43302. This variable displacement pump consists of a piston that reciprocates within a piston chamber provided in a cylinder block, a main shaft that rotationally drives the cylinder block, a swash plate that determines the stroke of the piston, and a swash plate that determines the stroke of the piston. It includes an operating cylinder that drives the plate, a bias cylinder that applies a bias force to the above-mentioned slant, and a valve plate that has a V-notch that communicates with the suction boat and the discharge boat. By gradually releasing the high-pressure fluid pressurized by the piston to the suction port through the V-notch near the top dead center, the pressurized fluid is prevented from being suddenly discharged to the suction port, causing vibration and noise. This is intended to reduce noise by reducing the excitation force that occurs. Also, similarly,
Near the bottom dead center, the V-notch communicating with the discharge port eliminates the rapid backflow from the discharge port to the piston chamber that occurs when the discharge port and the piston chamber communicate with each other, thereby reducing excitation force noise.

By the way, in a variable displacement pump having a plurality of reciprocating pistons, even if a notch is provided, suction pressure and discharge pressure inevitably remain in the piston chamber due to the rectifying action of the valve plate. Since it acts in the form of a rectangular wave, this becomes a direct excitation force for pump noise, and the fluid in the suction port and discharge boat that communicate with this piston chamber has a pulsating pressure as shown in Figure 13 due to its own compressibility. occurs. This pulse pressure becomes the second cause of noise and excitation force in devices including the pump. This pulsating pressure also causes pressure pulsations within the pipeline. Also,
In the above-mentioned conventional variable displacement pump, when the plurality of pistons move to a place where they communicate with the suction port or the discharge port, the inside of the piston is communicated with the discharge port and the suction boat through the V notch of the valve plate. but,
Even if the discharge pressure, rotation speed, etc. fluctuate, the V
Since the timing of communication between the discharge boat and suction boat and the interior of the piston through the notch cannot be changed, and the flow rate passing through the V-notch cannot be controlled, there is a problem in that noise is generated.

Therefore, the purpose of this invention is to provide a suction system for a plurality of pistons. The object of the present invention is to provide a low-noise variable displacement pump by alleviating the excitation force and noise caused by the discharge action and rectification action.

<Means for Solving the Problems> In order to achieve the above object, a first invention provides a piston that reciprocates within a piston chamber provided in a cylinder block, a main shaft that rotationally drives the cylinder block, and a stroke of the piston. A variable displacement pump comprising a stroke control member for controlling the stroke control member and an operation member for driving the stroke control member, the variable displacement pump having a rotation speed detector for detecting the rotation speed of the main shaft and receiving a signal from the rotation speed detector. hand,
A control device that outputs a control signal that has a functional relationship with the fundamental frequency of the pulse pressure in the piston chamber that is related to noise, and a fluid pressure that receives the control signal from the control device and that has a functional relationship with the fundamental frequency of the pulse pressure. The stroke control member is actuated via the operating member so as to change the pulse pressure in the piston chamber and reduce noise. It is characterized by

A second invention also provides a piston that reciprocates within a piston chamber provided in a cylinder block, a main shaft that rotationally drives the cylinder block, a stroke control member that controls the stroke of the piston, and a stroke control member that drives the stroke control member. In a variable displacement pump, the variable displacement pump is equipped with a pressure sensor that detects the pressure in the main line connected to the discharge port, and a signal from the pressure sensor that detects the basic pulse pressure in the piston chamber that is related to noise. a control device that outputs a control signal that has a functional relationship with frequency; and a fluid pressure that receives the control signal from the control device, generates fluid pressure that has a functional relationship with the fundamental frequency of the pulse pressure, and causes it to act on the operating member. The present invention is characterized in that a control valve is provided to operate a noise control member by changing the pulse pressure within the piston chamber.

Further, a third invention provides a piston that reciprocates within a piston chamber provided in a cylinder block, a main shaft that rotationally drives the cylinder block, a stroke control member that controls the stroke of the piston, and a stroke control member that drives the stroke control member. a control valve that controls fluid pressure applied to the operating member; and a control valve that operates in conjunction with the main shaft to control the control valve as a function of the fundamental frequency and pulse pressure of the pulsation pressure in the piston chamber. and a cam mechanism for actuating the control valve to output a related fluid pressure, the stroke control member being controlled via the operating member to change pulse pressure in the piston chamber and reduce noise. It is characterized by being made to operate.

Function> In the first invention, the rotation speed detector detects the rotation speed of the main shaft and outputs a signal corresponding to the rotation speed to the control device. Based on the signal from the rotational speed detector, the control device sends a control signal to the control valve, having a frequency that is in a functional relationship with the frequency of the pulse pressure in the piston chamber, and a phase that is in a functional relationship with the phase of the pulse pressure. Output. Based on this control signal, the control valve generates fluid pressure having a frequency and phase that are functionally related to the frequency and phase of the pulse pressure, and applies this fluid pressure to the operating member to move the stroke control member into the piston chamber. The pulse pressure is reduced. Therefore, noise is reduced.

Further, in the second invention, the pressure sensor detects the main line pressure, and the control device has a frequency that is in a functional relationship with the frequency of the pulse pressure in the piston chamber based on the signal from the pressure sensor, and A control signal having a phase that is in a functional relationship with the phase of the pulse pressure is output to the control valve. Based on this control signal, the control valve generates fluid pressure having a frequency and phase that are functionally related to the frequency and phase of the pulse pressure, and applies this fluid pressure to the operating member to move the stroke control member into the piston chamber. The pulse pressure is reduced. Therefore, noise is reduced.

Further, in the third invention, the cam mechanism works in conjunction with the main shaft to control the fluid pressure output from the control valve to a pressure having a frequency and phase that are in a functional relationship with the frequency and phase of the pulse pressure in the piston chamber. do. Therefore, the operating member receives this pressure and operates the stroke control member so that the pulse pressure within the piston chamber is reduced. Therefore, noise and vibration are reduced.

Example Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

In FIG. 1, 1 is a cylinder block, 2 is nine pistons (only two are shown) that reciprocate within a piston chamber provided in the cylinder block 1, 3 is a main shaft that rotationally drives the cylinder block l, and 5 is a main shaft that rotates the cylinder block l. A swash plate 6 which is an example of a stroke control member that controls the stroke of the piston 2
7 is an operating cylinder that is an operating member that drives the swash plate 5 in response to the pressure of the discharged fluid and controls the discharge amount of the variable pump; 7 is a bias ring that is an operating member that applies a bias force to the swash plate 5; 8 is the main line connected to the discharge port,
9 is a suction passage, which is basically the same as in the conventional technology.

Further, 11 is a rotary encoder as a rotation speed detector for detecting the rotation angle of the main shaft 3, and I2 receives a signal from the rotary encoder 11 and has a functional relationship with the frequency and phase of the pulse pressure in the piston chamber. A control device 13 that outputs a control signal is a servo valve serving as a control valve that receives a control signal from the control device 12 and outputs fluid pressure to the bias cylinder 7 according to the control signal.

The control device 12 has a configuration shown in FIG. 2, which will be described later, and the low-return encoder 11 outputs a signal representing zero phase and 3600 pulses per rotation of the main shaft 3. ing.

Next, the operation of the variable displacement pump having the above configuration will be explained.

As shown in FIG. 2, when the rotary encoder 11 outputs zero phase, the T flip-flop 21 is reset.
The τ output becomes "B", the AND gate 23 opens, and the pulse from the low reencoder 11 is passed through the AND gate 2.
Up-down counter 24 through 3
input to the side.

The up output and down output of the up/down counter 24 are inputted to the up side and the down side of an up/down counter 25, respectively. Up/down counters 24 and 25 each output 4 bits. The coincidence detection circuit 26 is designed to detect 100 pulses, and lO
Detect O pulse or 64H (H represents hexadecimal number). That is, the up/down counter 24 is 4H,
The coincidence detection circuit 26 detects whether or not the up-down counter 25 is 6H, and based on the output from the up-down counter 24.25, the coincidence detection circuit 26 detects the T of the T flip-flop 2l when it detects 100 pulses. A high level signal is input to the terminal, the T flip-flop 2l is inverted, the Q output is set to "B", the Q output is set to "0", the AND gate 22 is opened, the AND gate 23 is closed, and the up/down counter 24 is down. A pulse from the rotary encoder 11 is input to the (DOWN) side.When a signal is input to the down side of the up/down counter 24, both the up/down counters 24 and 25 count down.

Then, the coincidence detection circuit 26 uses an up/down counter 24
．． When it detects that a signal from 25 to 00 is input,
Input the match signal to the T terminal of the T Frisob Flob 2l,
Invert the T flip-flop 2l again and set the Q output to “0”
, the τ output is set to "B" and the above operations are repeated 18 times, the main shaft 3 rotates once, and the rotary encoder 11 outputs a zero-phase signal.At this time, the state of the T flip-flop 2l and the up/down counter 24.25 are The state of the output is shown in Figure 3.

In the above case, it is assumed that for each rotation of the main shaft 3, two pulsating pressures are generated in each piston chamber, and 18 pulsating pressures are generated in all 9 pistons, and the second harmonic component is large. , the coincidence detection circuit 26 detects 100 pulses, but when the fundamental wave component is large and there are 9 pulse pressures per rotation of the main shaft 3, the coincidence detection circuit 26 detects 200 pulses. Make it. Furthermore, when the pulsation of the 3rd and 4th harmonics is large, the number of pulses to be detected is changed accordingly.

On the other hand, the outputs of the up/down counters 24 and 25 are input to a ladder circuit 27, which generates 18 stepped triangular waves per rotation of the main shaft 3 to a sine wave generating circuit 28, as shown in FIG. Output (in Fig. 4,
steps are omitted). The sine wave generation circuit 28 generates a triangular wave created in a step-like manner in the ladder circuit 27.
Shape the waveform into a sine wave. The amplifier 29 converts the output from the sine wave generating circuit 28 into the output of a command signal from a manual setting device, a sensor (not shown) that detects the tilt of the swash plate, or a pressure sensor (not shown) that detects the magnitude of the discharge pressure. Accordingly, the amplitude is amplified according to the magnitude of the discharge pressure. Note that the amplifier 29 may be provided in the ladder circuit 27 to control the size of the step of the stairs.

The phase control circuit 30 uses a signal from a manual setting device, for example, to match the sine wave waveform from the rotary encoder 11 with the phase of the pulse pressure, or to advance the phase in accordance with the increase in the rotational speed of the main shaft 3. or based on the zero-phase output. The phase-controlled signal in this phase control circuit 30 is transmitted to the servo valve 1 in FIG.
3 is output.

The servo valve 13 receives the second signal from the phase control circuit 30.
Based on the harmonic control signal, the output fluid is controlled to act on the bias cylinder 7 to drive the swash plate 5 so as to reduce the pulsation pressure component in the piston chamber that is harmful to noise.

This occurs when fluid pressure is applied to the swash plate 5 by the bias cylinder 7 to reduce the excitation force in the piston chamber using the rotary encoder 11, the control device 12, and the servo valve 13 as in the above embodiment. After controlling the noise,
The noise generated in the conventional case without such control was subjected to frequency analysis. The results of the frequency analysis of the above embodiment are shown in the upper part of FIG. 5, and the results of the frequency analysis of the conventional variable displacement pump are shown in the lower part of FIG. From this, it can be seen that the noise in the above example is reduced at the second harmonic. (The fundamental wave is not shown in FIG. 5.) In this way, the bias cylinder 7 has a frequency. phase. By operating the swash plate 5 by applying the fluid force of the second harmonic with controlled amplitude, in addition to the effect of the notch, pump solid output noise is further alleviated, and noise reduction can be achieved. .

Further, the control device 12 adjusts the phase, amplitude, and frequency of the control signal to adjust the operation timing of the swash plate 5. Since the amplitude can be adjusted, the phase, amplitude, and frequency can be optimally set according to the discharge pressure, rotation speed, etc. of the variable displacement pump, thereby significantly reducing noise and vibration.

FIG. 6(a) shows a modification of the control device. This control device 112 includes an N-ary counter 113, an 8-bit read-only memory (hereinafter referred to as ROM) 114, and a D/A converter 1.
15, a gain phase adjustment circuit 116, and an amplifier 117, and further includes a central processing unit (CPU) not shown. The 8-bit ROM stores data values as shown in FIG. 6(b) corresponding to addresses 0 to (N-1). That is, the waveform shown in FIG. 6(b) is a waveform in which a fundamental wave and a third harmonic are superimposed. A waveform in which the fundamental wave and the third harmonic are synthesized in this way is stored in the 8-bit ROM 114 in advance.

Now, the rotary encoder 11 outputs a pulse of 9XN per revolution of the main shaft 3 shown in FIG. Then, the counter 113 counts the pulses from the low reencoder 11 and outputs the count value to the ROM 114 as an address signal. ROM 114 is the counter 11
3 and outputs a data signal to the D/A converter 115 to form a waveform as shown in FIG. 6(b). The D/A converter 115 D/A converts the data signal from the ROM 114 and outputs a waveform as shown in FIG. 6(b) to the gain/phase adjustment circuit 116.

The gain/phase adjustment circuit 116 adjusts the gain and also the phase of the signal having the waveform shown in FIG. 6(b) manually or by a command from the CPU, and outputs it to the servo valve 13 as a control signal via an amplifier 117. The control after the servo valve 13 is the same as in the embodiment shown in FIG.

In this control device 112, the waveform that is a combination of the fundamental wave and the third harmonic wave is stored in advance in the ROM 114, so the optimum control signal can be obtained with a simple configuration, and the pulse pressure in the piston chamber can be easily adjusted. This can be reduced accurately through configuration.

FIG. 7 shows another embodiment of the control device. This control device 212 includes an N-ary counter 113 and a ROM2 2 1, 2.
2 2, -, 2 2+++ and D/A converter 23l, 2
32,..., 23m and gain/phase adjustment circuit 241,
242, -, 24m, an adder circuit 251, an amplifier 252, and a CPU (not shown). The counter 113 counts 0 to (N-1). ROM221, 22,
. . , 22m stores data of O to 2π associated with each address in order to form a fundamental wave and each harmonic. The rotary encoder 11 outputs 9XN pulses per revolution of the main shaft 3 shown in FIG. The counter 113 counts the pulses from the low encoder and stores the count value from 0 to (N-1) in the ROM 221.
, 222, . . . , 22m as an address signal. The ROM2 2 1, 2 2 2, -, 22m converts the address signal from the counter 113 into a data signal for forming a fundamental wave and each harmonic to a D/A converter 231.
Output to 2 3 2, -, 2 3n+. The D/A converters 231, 232, . . . , 23m transmit signals representing respective sine wave patterns to a gain/phase adjustment circuit 241.2'.
42.・・・． Output to 24m. Then, these sine waves are transmitted to gain/phase adjustment circuits 241, 242, . . . , 2
4m, the gain and phase are appropriately adjusted manually or automatically and output to the adder circuit 251.

In the adder circuit 251, the signals forming the fundamental wave and the harmonics are added together and outputted to an amplifier 252, and outputted from the amplifier 252 to the servo valve 13 as a control signal.

In this way, in the control device 212 shown in FIG. 7, after adjusting an arbitrary number of harmonics and fundamental waves to an arbitrary gain and phase, it is possible to add them to form a control signal. Therefore, a control signal having an arbitrary waveform can be easily and inexpensively formed to reduce noise.

Note that in this embodiment, the rotary encoder 11 is connected to the main shaft 3.
Although it is designed to output 9XN pulses per revolution, if necessary, 18XN or 36X pulses can be output per revolution.
It is also possible to output N pulses.

FIG. 8 shows another embodiment of the control device.

This control device 312 includes an N-ary counter l13, a microprocessor 313, and a ROM3 1 53 1 6.3
1 7, D/A converter 327, and gain/phase adjustment circuit 3
28 and an amplifier 329.

The encoder 11 outputs 9XN pulses per revolution of the main shaft 3 shown in FIG. N-ary counter 113
counts 0 to (N-1) and outputs the count value to the microprocessor 313. ROM3 1 5
, 3 1 6, 3 1 7 have fundamental waves and harmonics stored in advance, and the microprocessor 313 stores data values corresponding to the count values in the ROM 3 1 5.3 1
6, 3 1 7, and add them to output a signal in which the fundamental wave and harmonics are synthesized to the D/A converter 327. The D/A converter 327 converts this combined signal into D
/A conversion and output to the gain/phase adjustment circuit 328.

The gain/phase adjustment circuit 328 manually or automatically adjusts the gain and phase of the analog signal received from the D/A converter 327, and outputs it to the servo valve 13 as a control signal via the amplifier 329.

Note that when the fundamental wave and harmonics are synthesized in the microprocessor 313, the ROM3 15, 3 1
In addition to adding the contents of 6, 3, 1, and 7, the gain and phase may be adjusted by the microprocessor 313 itself by multiplying each data by an appropriate number or shifting the phase of each data. good.

FIG. 9(a) shows another embodiment of the control device.

This control device 412 includes an N-ary counter 113 and a
) and a ROM 413 with a data width of m bits, which stores data in correspondence with addresses as shown in FIG. ,D,. .... D
low-pass filters 421, 4 2 2 receiving
, -, 4 2m and each low-pass filter 421, 422
,..., amplitude adjustment circuit 43 receiving signals from 42m
1,432.・”,43m and phase adjustment circuit 44 1
,442. .=, 44m, an adder circuit 451, an amplifier 452, and a CPU 2 (not shown). The encoder 11 outputs 9×N pulses per rotation of the main shaft 3. The counter 113 counts the signals from the low reencoder 11 and outputs the count value from 0 to (N-1) to the ROM 413 as an address signal. Here, for the sake of simplicity, for example, if N=10, the address signal takes values from 0 to 9 as shown in FIG. 9(b). Then, data D is stored in the ROM 433 as shown in FIG. 9(b) for these addresses O to 9. , DI, D
x, D3 are stored. Do is the fundamental wave data, D, is the second harmonic data, and the data D
, is the third harmonic data, and D3 is the fourth harmonic data. That is, based on the data in FIG. 9(b), pulses as shown in FIG. 9(c) are output. Each of the low-pass filters 421, 422, . ..., output to 43m. The sine waves whose amplitudes have been adjusted by the amplitude adjustment circuits 431, 432.43m are sent to the phase adjustment circuits 441.442, . . . , 4
The phase of the signal is adjusted by 4m and inputted to the adder circuit 451. Furthermore, the fundamental wave and the harmonics are added in an adder circuit 451 and output as a control signal from an amplifier 452.

In addition, in the above embodiment, the rotary encoders 11 to 9X
Although it is assumed that N pulses are output, the rotary encoder may output 18XN or 36XN pulses as necessary.

In addition, in the above embodiment, for simplicity, the number of pulses is N =
IO, but in actual implementation, the number of N should be a larger value. The greater the number of N, the higher the accuracy, and as can be seen from FIG. 9(C) when the number of pulses is large, there is no problem in practice even if there is an error of 2 to 3 pulses.

FIG. 10 shows another embodiment of the control device.

The control device 512 shown in FIG. 10 has counters 521, 522, .
n, and bandpass filters 531 532 . . . 5
3n, and the amplitude adjustment circuit 54 1,542,-. 54n, and phase adjustment circuits 551, 552, . 55n, an adder circuit 560, and an amplifier 570. The low rotation encoder outputs 9XN pulses per rotation of the main shaft 3. The maximum count value of the counter 521 is N, the maximum count value of the counter 522 is N/2, the maximum count value of the counter 523 is N/3, and the maximum count value of the counter 520 is N/3.
The maximum count value of the counter 52n is N/4, and the maximum count value of the counter 52n is N/n.

The output from the counter 521 is filtered through a band pass filter 531.
By passing the output from the counter 522 through the bandpass filter 532, nine sine waves are generated per one rotation of the main shaft 3, and two sine waves are output per one rotation of the main shaft 3. . Similarly, counter 52
By passing the output from the band pass filter 53n, a 9Xn times sine wave is generated per rotation of the main shaft. Such a sine wave is generated by amplitude adjustment circuits 541, 542.
-, 54n and the phase adjustment circuits 551, 552.55n, the amplitude and phase are adjusted, and then added in the adding circuit 560,
It is further amplified by an amplifier 570 and output as a control signal.

In this way, counter 5 2 1 . 5 2 2,-,
By changing the maximum count value of 52n, a fundamental wave and harmonics of arbitrary order can be formed. In addition, N
is selected as the least common multiple of 1, 2, 3,..., n.

FIG. 11 shows another embodiment. In Figure 11, the first
Parts with the same configuration as in the diagram are given the same numbers and explanations are omitted.
Only the different parts will be explained below.

Main line 8 connected to the discharge port of the variable displacement pump
The pressure is detected by a pressure sensor 601. A signal indicating pulsations in the main line 8 detected from the pressure sensor 601 is input to a bandpass filter 602, and only pulsations at a predetermined fundamental frequency are detected and input to the control device 12. This control device 12 is the control device 1 shown in FIGS.
Same as 2. This control device 12 generates a control signal that has a functional relationship with the frequency and phase of the pulsation pressure in the piston chamber that has a constant relationship with the pulsation of the main line 8, and outputs it to the control valve 13a. The control valve 13a is a 2-position, 3-boat servo valve or a proportional valve that outputs fluid pressure having a frequency and phase that are functionally related to the frequency and phase of the pulsating pressure in the piston chamber to the bias cylinder 7. 7 operates the swash plate 5 to reduce the pulse pressure within the piston chamber.

By doing so, the excitation force caused by the pulsating pressure within the piston chamber is reduced, and the generation of noise is significantly reduced.

In the above embodiment, the control valve 13a is a two-position valve, but it may be a three-position valve that can also pressurize the servo cylinder 6.

In addition, the control device is replaced with the control device I2 shown in FIG. 1, and includes a control device II2 shown in FIG. 6(a), a control device 212 shown in FIG. a)
A control device 412 shown in FIG. 10, a control device 512 shown in FIG.
may also be used. Further, although the number of pistons is nine, an even number may be used. In addition, in this embodiment, the control signal can be generated by the control device using a pressure sensor used for other purposes such as pressure control, so a rotary encoder as shown in FIG. 1 is not required, and costs can be reduced. It has the advantage of being able to

FIGS. 12(a) and 12(b) show other embodiments. 1st
In FIG. 2(a), parts having the same configuration as that shown in FIG. 1 are given the same numbers as in FIG. 1, and the explanation will be omitted, and only the different parts will be explained.

A main shaft 52 of the variable displacement pump of this embodiment projects on both sides of the cylinder block l, and a cam 53 is fixed to the end of the main shaft 52 via an electromagnetic clutch (not shown). This cam 53 has nine ridges on its outer periphery corresponding to the number of pistons 2, nine, as shown in FIG. 12(b). Further, the mounting phase angle of the cam 53 relative to the main shaft 54 can be adjusted as appropriate using an electromagnetic clutch. This cam 53 can press one end of the spool 5l of the control valve 50 via a cylindrical cam follower 55.

The spool 5l of the control valve 50 presses the cam follower against the cam 53 by a spring 60 pressing one end. The spool 51 of the control valve has three lands 5 6, 5 7.5 8, and is connected by the land 57 to the inlet boat 6l connected to the main line 8 of the variable displacement pump and the bias cylinder 7. The opening degree between the exit boat 62 and the exit boat 62 is controlled.

According to the variable displacement pump configured as described above, the cam 53 rotates in accordance with the rotation of the main shaft 52, and the spool 5l of the control valve 50 reciprocates nine times for each rotation of the main shaft 52. As a result, the pressure in the outlet boat 62 of the control valve 50 is reduced to the main shaft 5.
The fluid pressure acting on the bias cylinder 7 is controlled periodically, and each piston 2 moves from the suction stroke to the discharge stroke with each rotation of the main shaft 52. Shake 9 times to reduce pulse pressure.

The phase of the output of the control valve 50 can be adjusted by changing the phase angle at which the cam 53 is attached to the shaft 54. Further, it is desirable that the number of cam ridges on the cam 53 is changed depending on the frequency of pulse pressure in the piston chamber. control valve 50
The stroke is adjusted by changing the size of the cam crest of the cam 53 or by changing the diameter of the spool 5l of the control valve 50.

In this way, the bias cylinder 7 has the frequency and phase. By applying a fundamental wave fluid force with a controlled amplitude and operating the swash plate 5, the pistons 2 move to an intermediate position (bottom dead center) where they move from the suction boat to the discharge port, or the pistons move from the discharge port to the suction boat. At an intermediate position (top dead center) where the piston moves to , the fluid pressure within the piston can be changed in a pressure decreasing direction that is favorable for reducing pulse pressure.

In this way, since the pulsation pressure in the piston chamber can be reduced, pump solid output noise can be alleviated, and low noise can be achieved.

In the above embodiment, the fluid pressure from the control valve is applied to the bias cylinder, but in a variable displacement pump that does not have a bias cylinder and only has an operating cylinder, the fluid pressure from the control valve is applied to the operating cylinder. You may also add it. Further, both the operation cylinder and the bias cylinder may be controlled by a control valve.

Further, the control valve may be a three-way valve or a four-way valve. The operating cylinder may be double acting. Also,
Needless to say, the present invention can be applied to a swash plate type variable displacement pump as well as a swash plate type variable displacement pump.

Effects of the Invention According to the present invention, the control device generates a control signal that has a functional relationship with the fundamental frequency of the pulse pressure in the piston chamber, based on the signal from the rotation speed detector that detects the rotation angle of the main shaft. and output to the control valve, and from this control valve,
The fluid pressure that has a functional relationship with the fundamental frequency of the pulse pressure is output, and this fluid pressure is applied to the operating member to operate the stroke control member so that the pulse pressure in the piston chamber changes, so the excitation force is can be compensated for and significantly reduce noise.

Further, according to the present invention, the control device generates a control signal having a functional relationship with the fundamental frequency of the pulse pressure in the piston chamber based on the symbol from the pressure sensor that detects the pressure in the main line, and controls the control valve. This control valve outputs a fluid pressure that has a functional relationship with the fundamental frequency of the pulsation pressure, and this fluid pressure is applied to the operating member to cause the stroke control member to change the pulsation pressure in the piston chamber. Therefore, by using a pressure sensor that is also used for other pressure control, it is possible to compensate the excitation method with a simple and inexpensive structure, and to significantly reduce noise.

Further, according to the present invention, the fluid pressure output from the control valve is controlled by the cam mechanism interlocking with the main shaft to a pressure having a frequency and phase that are in a functional relationship with the frequency and phase of the pulse pressure in the piston chamber, Since this pressure is applied to the operating member and the stroke control member is operated so as to reduce the pulse pressure within the piston chamber, noise can be significantly reduced with only a simple mechanical configuration.

Further, according to the present invention, the control device controls the phase and amplitude of the control signal. The frequency can be adjusted, and the operation timing, amplitude and frequency of the stroke control member can be adjusted.
Discharge pressure of variable displacement pump. By optimally setting the phase, amplitude, and frequency according to the rotation speed, etc., noise can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram explaining an embodiment of a variable displacement pump of the present invention, FIG. 2 is a block diagram of a control device, and FIG. FIG. 4 is a diagram explaining the operation of the above embodiment, FIG. 5 is a spectrum diagram showing noise frequency analysis of the above embodiment and the conventional example, and FIG. 6(a). Figures 7 and 8. Figure 9(a), No.l
Figure 0 is a block diagram of another control device, Figure 6(b) is a diagram showing waveforms formed by data stored in memory, and Figure 9(b) is a diagram showing data stored in memory in Figure 9(a). FIG. 9(c) is a diagram showing the waveform generated based on the data in FIG. 9(b), and FIG. 11 and FIG. A conceptual diagram of another embodiment of the type pump, FIG. 12(b) is a sectional view of the cam mechanism,
FIG. 13 is a diagram illustrating the pulsation pressure at the discharge port and suction port connected to the piston chamber. l...Cylinder block, 2...Piston, 3.5
2...Main shaft, 5...Swash plate, 6...Operation cylinder,
7...Bias cylinder, 12,112,212,312,412,512-control device, 13,13a,50--control valve, 601...pressure sensor. Patent applicant Daikin Industries, Ltd.

Claims (14)

[Claims] (1) A piston (2) that reciprocates in a piston chamber provided in the cylinder block (1), and a piston (2) that reciprocates in a piston chamber provided in the cylinder block (1), and
1) and the main shaft (3) that rotationally drives the piston (2).
a stroke control member (5) that controls the stroke of the
An operating member (7) that drives the stroke control member (5)
), a rotation speed detector (11) for detecting the rotation speed of the main shaft (3).
), and a control device (12, 112, 21) that receives the signal from the rotation speed detector (11) and outputs a control signal that has a functional relationship with the fundamental frequency of the pulse pressure in the piston chamber related to noise.
2,312,412,512) and the control device (12
, 112, 212, 312, 412, 512), the control valve (13) generates a fluid pressure having a functional relationship with the fundamental frequency of the pulse pressure and causes it to act on the operating member (7). ), and the operating member (7) is configured to change the pulse pressure in the piston chamber and reduce noise.
). A variable displacement pump characterized in that the stroke control member (5) is controlled via the stroke control member (5). (2) In the variable displacement pump according to claim 1, the control device (12) includes a phase control circuit (30) for adjusting the phase of the control signal, and a phase control circuit (30) for adjusting the amplitude of the control signal. A variable displacement pump including an amplifier circuit (29). (3) In the variable displacement pump according to claim 1, the control device (112) forms a predetermined waveform with a counter (113) that counts pulses from the rotation speed detector (11). a memory (114) which stores data in association with addresses in order to generate the waveform, receives an address signal from the counter (113), and outputs a data signal for forming the waveform;
14) and a D/A converter (115) that receives a signal from the D/A converter (115) and converts the signal from D/A to D/A.
) A variable displacement pump including a gain phase adjusting means (116) for adjusting the amplitude and phase of an analog signal output from the converter. (4) In the variable displacement pump according to claim 1, the control device (212) includes a counter (113) that counts pulses from the rotation speed detector (11), and a counter (113) that counts pulses from the rotation speed detector (11), and a plurality of memories (221, 222) that store data in association with addresses to form the waveform, and output data signals for forming the waveform in response to each address signal from the counter (113);
, a plurality of D/A converters (231, 232) that receive each signal from the plurality of memories (221, 222) and D/A convert the respective signal, and each of the D/A converters ( 23
A plurality of gain phase adjustment means (241, 2) for adjusting the amplitude and phase of the analog signals respectively output from
42) and each of the gain phase adjustment means (241, 242)
) A variable displacement pump including an adding circuit (251) that adds signals output from the above. (5) In the variable displacement pump according to claim 1, the control device (412) forms a predetermined waveform with a counter (113) that counts pulses from the rotation speed detector (11). a memory (413) which stores data in association with an address to generate the waveform, receives an address signal from the counter (113), and outputs a data signal for forming the waveform;
a plurality of low-pass filters (421, 422) each receiving a signal of a predetermined bit from 13), and a plurality of gain phase adjustments for adjusting the amplitude and phase of the analog signal output from each of the above-mentioned low-pass filters (421, 422), respectively. means (441, 442), and each gain phase adjustment means (441, 442);
441, 442); (6) In the variable displacement pump according to claim 1, the control device (512) includes a plurality of control devices each having a maximum count value set to be different from each other and each counting pulses from the rotation speed detector (11). counter (521, 52
2) and a plurality of bandpass filters (531, 53) that receive signals from each of the counters (521, 522), respectively.
2) and each of the above bandpass filters (531, 532)
A plurality of gain phase adjustment means (541, 551; 542) for adjusting the amplitude and phase of the analog signals respectively output from the
, 552) and each gain phase adjustment means (541, 5
51; 542, 552). (7) A piston (2) that reciprocates within a piston chamber provided in the cylinder block (1), and a piston (2) that reciprocates in a piston chamber provided in the cylinder block (1), and
1) and the main shaft (3) that rotationally drives the piston (2).
a stroke control member (5) that controls the stroke of the
An operating member (7) that drives the stroke control member (5)
), a pressure sensor (601) that detects the pressure of the main line (8) connected to the discharge port; A control device (12, 112, 21) that outputs a control signal that has a functional relationship with the fundamental frequency of the pulse pressure in the piston chamber.
2,312,412,512) and the control device (12
, 112, 212, 312, 412, 512), the control valve (13) generates a fluid pressure having a functional relationship with the fundamental frequency of the pulse pressure and causes it to act on the operating member (7). ), and the operating member (
7) A variable displacement pump characterized in that the stroke control member (5) is controlled via the above-mentioned stroke control member (5). (8) In the variable displacement pump according to claim 7, the control device (12, 112, 212, 312, 412,
The control valve (13a) receives the signal from the pressure sensor (601) via the band-pass filter (602) and sends a control signal having a functional relationship with the fundamental frequency of the pulse pressure in the piston chamber related to noise. ) variable displacement pump that outputs to (9) In the variable displacement pump according to claim (8), the control device (12) includes a phase control circuit (30) for adjusting the phase of the control signal, and a phase control circuit (30) for adjusting the phase of the control signal. A variable displacement pump including an amplifier circuit (29) for adjustment. (10) In the variable displacement pump according to claim 8,
The control device (112) controls the bandpass filter (
a counter (113) that counts pulses from (602)
), data is stored in association with the address to form a predetermined waveform, and the counter (11
A memory (114) which receives an address signal from the memory (114) and outputs a data signal for forming the waveform;
A variable displacement pump including a D/A converter (115) that performs A conversion, and gain phase adjustment means (116) that adjusts the amplitude and phase of an analog signal output from the D/A converter (115). (11) In the variable displacement pump according to claim 8,
The control device (212) controls the bandpass filter (
a counter (113) that counts pulses from (602)
), and data is stored in association with addresses in order to form each predetermined waveform, and the counter (1
A plurality of memories (221) receive each address signal from 13) and output data signals for forming the above waveform
, 222), a plurality of D/A converters (231, 232) that receive each signal from the plurality of memories (221, 222) and convert each of the above signals into D/A, and each of the D/A converters (231, 232). A plurality of gain phase adjustment means (
241, 242) and each of the gain phase adjustment means (24
1,242) for adding the signals output from the adder circuit (
251) A variable displacement pump comprising: (12) In the variable displacement pump according to claim 8,
The control device (412) controls the bandpass filter (
a counter (113) that counts pulses from (602)
), data is stored in association with the address to form a predetermined waveform, and the counter (11
A memory (413) that receives an address signal from the memory (413) and outputs a data signal for forming the waveform, and a plurality of low-pass filters (421, 422) that each receive a predetermined bit signal from the memory (413). ), a plurality of gain phase adjustment means (441, 442) for adjusting the amplitude and phase of the analog signals output from each of the above-mentioned low-pass filters (421, 422), and each of the above-mentioned gain phase adjustment means (441, 442). A variable displacement pump including an adding circuit (451) that adds signals output from the pump. (13) In the variable displacement pump according to claim 8,
The control device (512) is configured such that the maximum count values are different from each other, and the bandpass filter (602) is configured such that the maximum count values are different from each other.
), a plurality of counters (5
21, 522) and each of the above counters (521, 522)
A plurality of bandpass filters (5 bandpass filters each receiving signals from
31, 532) and each of the above bandpass filters (531
, 532), a plurality of gain phase adjustment means (541, 55
1:542,552) and each of the above gain phase adjustment means (
541, 551: 542, 552). (14) A piston (2) that reciprocates within a piston chamber provided in the cylinder block (1), a main shaft (52) that rotationally drives the cylinder block (1), and a main shaft (52) that rotationally drives the cylinder block (1);
Stroke control member (5) that controls the stroke of 2)
and an operating member (7) that drives the stroke control member (5), the control valve (50) controlling fluid pressure acting on the operating member (7), and the main shaft ( In conjunction with the control valve (52), the control valve (50)
The control valve (50
) and a cam mechanism (53) for operating the stroke control member (5) via the operation member (7) so as to change the pulse pressure in the piston chamber and reduce noise.
A variable displacement pump characterized in that it operates.